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WO2025165990A1 - Guides d'ondes à polarisation périodique et leurs procédés de fabrication et d'utilisation - Google Patents

Guides d'ondes à polarisation périodique et leurs procédés de fabrication et d'utilisation

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Publication number
WO2025165990A1
WO2025165990A1 PCT/US2025/013775 US2025013775W WO2025165990A1 WO 2025165990 A1 WO2025165990 A1 WO 2025165990A1 US 2025013775 W US2025013775 W US 2025013775W WO 2025165990 A1 WO2025165990 A1 WO 2025165990A1
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WIPO (PCT)
Prior art keywords
temperature
periodically poled
poling
waveguide
region
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PCT/US2025/013775
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English (en)
Inventor
Daniel Gauthier
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Ohio State Innovation Foundation
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Ohio State Innovation Foundation
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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/355—Non-linear optics characterised by the materials used
    • G02F1/3558—Poled materials, e.g. with periodic poling; Fabrication of domain inverted structures, e.g. for quasi-phase-matching [QPM]
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/365—Non-linear optics in an optical waveguide structure
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/20—LiNbO3, LiTaO3

Definitions

  • Spontaneous parametric down conversion is a process for generating entangled photon pairs. This is a key technology for the rapidly expanding field of quantum information science. In current approaches, the temperature of the device has to be controlled to well below 1 degree centigrade, increasing the cost and complexity of the device. There will likely be a world-wide effort in developing long-distance quantum communication networks using these sources and so there is a great desire to develop a source that can operate over a wide temperature range in the field without the complexity and cost of using a large size, weight, and power temperature controller. The devices and methods discussed herein address these and other needs.
  • the disclosed subject matter relates to periodically poled waveguides and methods of making and use thereof.
  • the disclosed subject matter relates to devices and methods for reducing the temperature sensitivity of spontaneous parametric down conversion.
  • periodically poled waveguides comprising: a first poling region having a first poling period; and a second poling region having a second poling period; wherein the first poling period is phase matched at a first temperature and the second poling period is phase matched at a second temperature, the first poling period being different than the second poling period such that the first temperature is different than the second temperature.
  • the periodically poled waveguide comprises barium borate, barium titanate, bismuth germanate, cadmium zinc telluride, cesium lithium borate, gallium(II) selenide, lithium iodate, lithium niobate (LiNbCh), lithium tantalate, lithium triborate, Nd:YCOB (Nd- doped YCOB, Nd:YCa4O(BO3)3), potassium aluminum borate, potassium dideuterium phosphate, potassium niobate, potassium titanyl phosphate, tellurium dioxide, terbium gallium garnet, yttrium iron garnet, or a combination thereof.
  • the periodically poled waveguide comprises LiNbCh. In some examples, the periodically poled waveguide comprises LiNbCh doped with a dopant.
  • the periodically poled waveguide consists essentially of LiNbCh. In some examples, the periodically poled waveguide consists of LiNbCh.
  • the periodically poled waveguide consists essentially of the first poling region and the second poling region.
  • the periodically poled waveguide consists of the first poling region and the second poling region.
  • the periodically poled waveguide has a total length
  • the first poling region has a first length
  • the second poling region has a second length
  • the first length and the second length combining to provide the total length.
  • the first length and the second length are the same.
  • the temperature bandwidth of the device is increased to 17°C relative to a temperature bandwidth of 5°C for similar device consisting of a single poling region.
  • the periodically poled waveguide further comprises a third poling region having a third poling period, the third poling period being phase matched at a third temperature, the third poling period being different than both the first poling period and the second poling period, such that the third temperature is different than both the first temperature and the second temperature.
  • the periodically poled waveguide comprises one or more additional poling regions, each of the one or more additional poling regions having a poling period that is phase matched a temperature, wherein each of the poling periods is different than each other such that each phase matched temperature is different than each other.
  • the total number of poling regions in the periodically poled waveguide is 3 or more, 4 or more, 5 or more, 10 or more, 25 or more, 50 or more, or 100 or more.
  • the periodically poled waveguide is monolithic.
  • each of the poling regions comprises a separate crystal, each of the crystals being separated from a neighboring crystal by a gap, which together form the periodically poled waveguide.
  • the periodically poled waveguide is less temperature sensitive relative to a waveguide consisting of a single poling region.
  • the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is increased relative to the temperature bandwidth of a waveguide consisting of a single poling region.
  • the periodically poled waveguide has a temperature bandwidth
  • the temperature bandwidth of the periodically poled waveguide is increased by a factor of two or more (e.g., three or more) relative to the temperature bandwidth of a waveguide consisting of a single poling region.
  • the periodically poled waveguide has a temperature bandwidth
  • the temperature bandwidth of the periodically poled waveguide is 5°C or more, 10°C or more, 15°C or more, 35°C or more, 40°C or more, 50°C or more, 75°C or more, 100°C or more, 150°C or more, or 180°C or more.
  • the periodically poled waveguide has a temperature bandwidth; during use, the periodically poled waveguide is operated at an operation temperature; and the periodically poled waveguide is configured such that the operation temperature is within the temperature bandwidth of the periodically poled waveguide.
  • the device further comprises a temperature controller.
  • the temperature controller is configured to stabilize the temperature differential between the first and second poling regions.
  • the first poling region is a high- temperature region and the second poling region is a low-temperature region, and wherein the temperature controller is configured to stabilize the temperature of the high-temperature region relative to the low-temperature region.
  • the device generates photon pairs via spontaneous parametric down conversion. In some examples, the photon pairs are entangled.
  • the device generates entangled photon pairs via spontaneous parametric down conversion.
  • the device generates a plurality of photons (e.g., two or more, three or more, or four or more) via spontaneous parametric down conversion
  • the device is a quantum information device.
  • the device comprises a drone, a satellite, or a combination thereof.
  • the device is configured for a terrestrial application.
  • the device is configured for an extra-terrestrial application.
  • the method comprises using the periodically poled waveguide in any of the devices disclosed herein.
  • the method comprises using the periodically poled waveguide or device to generate photon pairs via spontaneous parametric down conversion.
  • the photon pairs are entangled.
  • the method comprises using the periodically poled waveguide or device to generate entangled photon pairs via spontaneous parametric down conversion.
  • the method comprises using the periodically poled waveguide or device to generate a plurality of photons (e.g., two or more, three or more, or four or more) via spontaneous parametric down conversion.
  • a plurality of photons e.g., two or more, three or more, or four or more
  • the method comprises using the periodically poled waveguide or device in a quantum information application.
  • the method comprises using the periodically poled waveguide or device in a drone, a satellite, or a combination thereof.
  • the method comprises using the periodically poled waveguide or device in a terrestrial application.
  • the method comprises using the periodically poled waveguide or device in an extra-terrestrial application.
  • periodically-poled LiNbCh waveguides comprising: a first poling region; and a second poling region, wherein a poling period of the first poling region or the second poling region is phase matched at two different temperatures.
  • a respective poling period of each of the first poling region and the second poling region is phase matched at two different temperatures.
  • a temperature bandwidth is increased from about 5 °C to about 17 °C.
  • the first poling region is a high-temperature region and the second poling region is a low-temperature region. In some examples, only the first poling region is stabilized.
  • a differential heating method is used for the waveguide.
  • waveguides and methods as described herein are also disclosed herein.
  • Figure 2A shows the efficiency curve for the two-region case when the poling period in the second region is 18.950 pm when the temperature is 30.8°C according to an implementation described herein.
  • Figure 4A- Figure 4B Figure 4A) The deviation of each index of refraction for LiNbCh from its value at an ambient temperature of 20°C. The extraordinary index of refraction is more sensitive to changes in temperature.
  • Figure 4B The change in region thickness compared to its phase-matched value at 20 °C (18.990 pm). The plots are generated using the Sellmeier equation with coefficients given in Bartnick et al., Phys. Rev. Appl. 2021, 15, 024028 and the thermal expansion perpendicular to the crystal axis from https://www.bostonpiezooptics.com/lithium- niobate.
  • Figure 5A- Figure 5B Figure 5A) The typical design of periodically-poled waveguides, with one poling period, and Figure 5B) the waveguide described herein, where a second region is introduced with a different poling period. The regions are not to scale, the large difference in poling period is for illustrative purposes.
  • Figure 7A- Figure 7B Compensating a manufacturing error using a differential temperature adjustment.
  • FIG. 8A- Figure 8B The effect of pump wavelength detuning on the shape of the relative efficiency curve over the crystal’s temperature for both the Figure 8 A) one-region and Figure 8B) two-region waveguide. Three cases of pump wavelength detuning are shown for each.
  • Figure 13A- Figure 13B The relative efficiency of down conversion for Figure 13A) one- region and a Figure 13B) two-region waveguide.
  • the curves represent different phase-matching configurations: Type 0 eee (blue), Type 0 ooo (red), and Type II oeo (yellow).
  • FIG. 16 An example waveguide described herein, having a first region with a first poling period and a second region is with a different poling period, where the first poling region and the second poling region are different crystals separated by a gap.
  • the regions and the gap are not to scale, the large difference in poling period is for illustrative purposes.
  • Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. By “about” is meant within 5% of the value, e.g., within 4, 3, 2, or 1% of the value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. Values can be expressed herein as an “average” value. “Average” generally refers to the statistical mean value.
  • substantially is meant within 5%, e.g., within 4%, 3%, 2%, or 1%.
  • references in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed.
  • X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.
  • a weight percent (wt. %) of a component is based on the total weight of the formulation or composition in which the component is included.
  • A, B, C, or combinations thereof refers to all permutations and combinations of the listed items preceding the term.
  • “A, B, C, or combinations thereof’ is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.
  • expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CAB ABB, and so forth.
  • the skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.
  • Described herein are periodically poled waveguides and methods of making and use thereof.
  • the disclosed subject matter relates to devices and methods for reducing the temperature sensitivity of spontaneous parametric down conversion.
  • periodically poled waveguides comprising at least two poling regions, where in each poling region is phase matched at a different temperature.
  • periodically poled waveguides comprising: a first poling region having a first poling period; and a second poling region having a second poling period; wherein the first poling period is phase matched at a first temperature and the second poling period is phase matched at a second temperature, the first poling period being different than the second poling period such that the first temperature is different than the second temperature.
  • the periodically poled waveguide can comprise a suitable material, such as a crystal.
  • suitable material such as a crystal.
  • periodically poled waveguide materials include, but are not limited to, barium borate, barium titanate, bismuth germanate, cadmium zinc telluride, cesium lithium borate, gallium(II) selenide, lithium iodate, lithium niobate (LiNbCh), lithium tantalate, lithium triborate, Nd:YCOB (Nd-doped YCOB, Nd:YCa4O(BO3)3), potassium aluminum borate, potassium dideuterium phosphate, potassium niobate, potassium titanyl phosphate, tellurium dioxide, terbium gallium garnet, yttrium iron garnet, or a combination thereof.
  • the periodically poled waveguide comprises LiNbCh. In some examples, the periodically poled waveguide comprises LiNbCh doped with a dopant.
  • the periodically poled waveguide consists essentially of LiNbCh. In some examples, the periodically poled waveguide consists of LiNbCh.
  • the periodically poled waveguide consists essentially of the first poling region and the second poling region. In some examples, the periodically poled waveguide consists of the first poling region and the second poling region.
  • the periodically poled waveguide consists essentially of LiNbCh and the periodically poled waveguide consists essentially of the first poling region and the second poling region.
  • the periodically poled waveguide consists of LiNbCh and the periodically poled waveguide consists of the first poling region and the second poling region.
  • the periodically poled waveguide has a total length
  • the first poling region has a first length
  • the second poling region has a second length
  • the first length and the second length combining to provide the total length.
  • the first length and the second length are the same.
  • the periodically poled waveguide consists of the first poling region and the second poling region, the periodically poled waveguide has a total length, the first poling region has a first length, and the second poling region has a second length, the first length and the second length combining to provide the total length, wherein the first length and the second length are the same, wherein the periodically poled waveguide consists of LiNbCh, and the temperature bandwidth of the periodically poled waveguide is increased to 17°C relative to a temperature bandwidth of 5°C for a waveguide consisting of a single poling region.
  • the periodically poled waveguide further comprises a third poling region having a third poling period, the third poling period being phase matched at a third temperature, the third poling period being different than both the first poling period and the second poling period, such that the third temperature is different than both the first temperature and the second temperature.
  • the periodically poled waveguide comprises one or more additional poling regions, each of the one or more additional poling regions having a poling period that is phase matched a temperature, wherein each of the poling periods is different than each other such that each phase matched temperature is different than each other.
  • the total number of poling regions in the periodically poled waveguide is 3 or more (e.g., 4 or more, 5 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, 70 or more, 75 or more, 80 or more, 85 or more, 90 or more, 95 or more, or 100 or more).
  • the total number of poling regions in the periodically poled waveguide is 4 or more.
  • the total number of poling regions in the periodically poled waveguide is 5 or more.
  • the total number of poling regions in the periodically poled waveguide is 10 or more.
  • the total number of poling regions in the periodically poled waveguide is 25 or more. In some examples, the total number of poling regions in the periodically poled waveguide is 50 or more. In some examples, the total number of poling regions in the periodically poled waveguide is 100 or more.
  • the periodically poled waveguide is monolithic.
  • the periodically poled waveguide is not monolithic.
  • each of the poling regions can comprise a separate crystal, each of the crystals being separated from the neighboring crystal by a gap, that together form the periodically poled waveguide, for example as shown in Figure 16.
  • the periodically poled waveguide can comprise a first poling region and a second poling region, the first poling region comprising a first crystal having a first length, the second poling region comprising a second crystal having a second length, the first crystal being separated from the second crystal by a gap.
  • the first length and the second length are the same.
  • the periodically poled waveguide is less temperature sensitive relative to a waveguide consisting of a single poling region.
  • the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is increased relative to the temperature bandwidth of a waveguide consisting of a single poling region.
  • the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is increased by a factor of two or more (e.g., three or more) relative to the temperature bandwidth of a waveguide consisting of a single poling region. In some examples, the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is increased by a factor of three or more relative to the temperature bandwidth of a waveguide consisting of a single poling region. In some examples, the temperature bandwidth of the periodically poled waveguide is increased to 17°C relative to a temperature bandwidth of 5°C for a waveguide consisting of a single poling region.
  • the periodically poled waveguide has a temperature bandwidth
  • the temperature bandwidth of the periodically poled waveguide is 5°C or more (e.g., 10°C or more, 15°C or more, 20°C or more, 25°C or more, 30°C or more, 35°C or more, 40°C or more, 45°C or more, 50°C or more, 60°C or more, 70°C or more, 80°C or more, 90°C or more, 100°C or more, 110°C or more, 120°C or more, 130°C or more, 140°C or more, 150°C or more, 160°C or more, 170°C or more, or 180°C or more).
  • the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is 10°C or more. In some examples, the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is 15°C or more. In some examples, the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is 35°C or more. In some examples, the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is 40°C or more. In some examples, the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is 50°C or more.
  • the periodically poled waveguide has a temperature bandwidth, and, during use, the periodically poled waveguide is operated at an operation temperature, and the periodically poled waveguide is configured such that the operation temperature is within the temperature bandwidth of the periodically poled waveguide.
  • periodically-poled LiNbCh waveguides comprising: a first poling region; and a second poling region, wherein a poling period of the first poling region or the second poling region is phase matched at two different temperatures.
  • a respective poling period of each of the first poling region and the second poling region is phase matched at two different temperatures.
  • a temperature bandwidth is increased from about 5 °C to about 17 °C.
  • the first poling region is a high-temperature region and the second poling region is a low-temperature region. In some examples, only the first poling region is stabilized. In some examples, a differential heating method is used for the waveguide.
  • waveguides and methods as described herein are also disclosed herein.
  • devices comprising any of the periodically poled waveguides described herein.
  • the device further comprises a temperature controller.
  • the temperature controller is configured to stabilize the temperature differential between the first and second poling regions.
  • the first poling region is a high- temperature region and the second poling region is a low-temperature region, and wherein the temperature controller is configured to stabilize the temperature of the high-temperature region relative to the low-temperature region.
  • the device generates photon pairs via spontaneous parametric down conversion. In some examples, the photon pairs are entangled.
  • the device generates entangled photon pairs via spontaneous parametric down conversion.
  • the device generates a plurality of photons (e.g., two or more, three or more, or four or more) via spontaneous parametric down conversion.
  • the device is less temperature sensitive relative to a device comprising a waveguide consisting of a single poling region.
  • the device is a quantum information device.
  • the device comprises a drone, a satellite, or a combination thereof.
  • the device is configured for a terrestrial application.
  • the device is configured for an extra-terrestrial application.
  • the method comprises using the periodically poled waveguide or device to generate photon pairs via spontaneous parametric down conversion.
  • the photon pairs are entangled.
  • the method comprises using the periodically poled waveguide or device to generate entangled photon pairs via spontaneous parametric down conversion.
  • the method comprises using the periodically poled waveguide or device to generate a plurality of photons (e.g., two or more, three or more, or four or more) via spontaneous parametric down conversion.
  • a plurality of photons e.g., two or more, three or more, or four or more
  • the method comprises using the periodically poled waveguide or device in a quantum information application.
  • the method comprises using the periodically poled waveguide or device in a drone, a satellite, or a combination thereof.
  • the method comprises using the periodically poled waveguide or device in a terrestrial application.
  • the method comprises using the periodically poled waveguide or device in an extra-terrestrial application.
  • Spontaneous parametric down conversion is a process for generating entangled photon pairs. This is a key technology for the rapidly expanding field of quantum information science. In current approaches, the temperature of the device has to be controlled to well below 1 degree centigrade, increasing the cost and complexity of the device. There will likely be a world-wide effort in developing long-distance quantum communication networks using these sources and so there is a great desire to develop a source that can operate over a wide temperature range in the field without the complexity and cost of using a large size, weight, and power temperature controller.
  • phase-matching can be achieved by adjusting the direction of propagation of the pump, signal, and idler waves with respect to the crystalline axes (so-called angle tuning). Another approach is to take advantage of the dependence of the index of refraction of the material with respect to temperature (temperature tuning). Depending on the wavelengths of the pump, signal, and idler waves, it is not always possible to achieve phase matching. In some of these cases, it is possible to periodically invert the direction of the crystal axis to achieve what is known as phase-matching by periodic poling (MM Fejer et al. IEEE J. Quantum Electron. 1992, 28, 2631).
  • the temperature must be tightly controlled to maintain perfect phase-matching.
  • the typical temperature stabilization method is to place the nonlinear crystal in a large oven that creates a uniform and controlled temperature over the entire crystal length. More compact designs are possible by directly depositing heating elements on one side of the crystal (G Chen et al. IEEE Photonics J. 2021, 13, 6600409), although the range in achievable temperatures may be limited in this method because large thermal gradients will crack the crystal.
  • a design for reducing the temperature sensitivity for spontaneous parametric down conversion (SPDC) with a specific design presented for periodically-poled LiNbCh waveguides is provided.
  • SPDC spontaneous parametric down conversion
  • the design uses two distinct poling regions, each with a poling period selected for phase matching at two different temperatures.
  • the temperature bandwidth is increased from ⁇ 5°C to ⁇ 17°C using this approach, while only reducing the overall efficiency of the process by a factor of 4.
  • the bandwidth is large enough so that controlling the overall temperature of the nonlinear crystal is likely not needed in a laboratory environment or can be achieved using a low size, weight, and power temperature controller design for field-deployed sources.
  • differential heating method is used where only the temperature of the high-temperature region is stabilized relative to the low-temperature region.
  • the differential temperature stabilization method requires a smaller, lighter weight heater and lower power than other approaches, thus greatly simplifying the overall design.
  • the temperature-dependent refractive index (Bartnick et al., Phys. Rev. Appl. 2021, 15, 024028) and the thermal expansion of the grating is considered using a thermal expansion coefficient of 7.5* 10' 6 along a direction perpendicular to the crystalline “c” axis (https://www.bostonpiezooptics.com/lithium-niobate), that is, along the direction of propagation of the light in the waveguide.
  • One aspect of the design is to adjust the poling period along the length of the crystal so that different regions are phase-matched at different temperatures. Thus, there is always one region that will contribute to the SPDC process at some temperature.
  • the downside of this approach is that the effective length of the interaction region is less than the crystal length, thereby reducing the efficiency . For future reference, the efficiency scales as L 2 for an ideal SPDC interaction.
  • the phase-mismatch is predicted as a function of temperature for the Type 0 phasematching configuration (pumping with an e-wave, generating two e-waves), which has the highest nonlinearity and hence the highest SPDC efficiency for a given pump power.
  • the value of Ti is optimized by re-running the simulation for different values of Ti and selecting the one that has the most uniform response over the temperature range. Other variations are possible, such as having the first region at a different temperature or having the second region cooler than the first region.
  • Figure 1 shows temperature bandwidth for different SPDC polarization configurations in periodically-poled lithium niobate.
  • the first case using a single poling period blue line
  • the ripples in the efficiency curve can be reduced by using more step regions, using a continuous linear chirp in the poling period, apodizing the grating, etc.
  • these approaches come at an increased manufacturing cost but may be worthwhile in some designs where a flat efficiency curve is an important metric.
  • Another approach is to adjust the pump laser power as the temperature changes, thus reducing the variation in efficiency of the overall system.
  • the shape of the efficiency curve is sensitive to small errors in the relative poling period between the two regions because there is interference from the generated SPDC fields in the two regions. Described herein is a technique to compensate from such errors by making a small adjustment to the temperate AZ to the second region relative to the first; that is, by making a differential change in the temperature along the crystal.
  • Figure 2A- Figure 2B shows compensating a manufacturing error using a differential temperature adjustment.
  • Figure 2A shows the efficiency curve for the two-region case when the poling period in the second region is 18.950 pm when the temperature is 30.8°C. This is a 6.3 nm error in the poling period. The efficiency curve is clearly distorted in comparison to the ideal case shown in Figure 1 when the temperature is uniform along the crystal.
  • the overall temperature of the crystal does not need to be controlled, but only the temperature difference of the two regions.
  • AZ is small, which will only require a small, lightweight and low power temperature controller to maintain a relatively flat efficiency curve over a wide overall temperature range.
  • FPGAs Field- programmable Gate Arrays
  • ASICs Application-specific Integrated Circuits
  • ASSPs Application-specific Standard Products
  • SOCs System-on-a-chip systems
  • CPLDs Complex Programmable Logic Devices
  • the methods and apparatus of the presently disclosed subject matter may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium where, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the presently disclosed subject matter.
  • program code i.e., instructions
  • tangible media such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium
  • exemplary implementations may refer to utilizing aspects of the presently disclosed subject matter in the context of one or more stand-alone computer systems, the subject matter is not so limited, but rather may be implemented in connection with any computing environment, such as a network or distributed computing environment. Still further, aspects of the presently disclosed subject matter may be implemented in or across a plurality of processing chips or devices, and storage may similarly be effected across a plurality of devices. Such devices might include personal computers, network servers, and handheld devices, for example.
  • a design for reducing the temperature sensitivity for spontaneous parametric down conversion (SPDC) with a specific design presented for periodically-poled LiNbCh waveguides is provided.
  • the design uses two distinct poling regions, each with a poling period selected for phase matching at two different temperatures.
  • the temperature bandwidth is increased from ⁇ 5°C to ⁇ 17°C using this approach, while only reducing the overall efficiency of the process by a factor of 4.
  • the bandwidth is large enough so that controlling the overall temperature of the nonlinear crystal is likely not needed in a laboratory environment or can be achieved using a low size, weight, and power temperature controller design for field-deployed sources.
  • differential heating method is used where only the temperature of the high-temperature region is stabilized relative to the low-temperature region.
  • the differential temperature stabilization method requires a smaller, lighter weight heater and lower power than other approaches, thus greatly simplifying the overall design.
  • a periodically-poled LiNbCh waveguide comprising: a first poling region; and a second poling region, wherein a poling period of the first poling region or the second poling region is phase matched at two different temperatures.
  • a respective poling period of each of the first poling region and the second poling region is phase matched at two different temperatures.
  • a temperature bandwidth is increased from about 5°C to about 17°C.
  • the first poling region is a high-temperature region and the second poling region is a low-temperature region. In some examples, only the first poling region is stabilized. In some examples, a differential heating method is used for the waveguide.
  • Also disclosed herein is a waveguide and method as described herein.
  • Spontaneous parametric down-conversion sources are typically highly temperature sensitive. Periodically poled waveguides with two cascading regions that are phase- matched to different temperatures can potentially more than double the operating temperature bandwidth.
  • SPDC spontaneous parametric downconversion
  • phase-matching In cases where phase-matching is not possible, quasi -phase-matching (QPM) is realized through periodic poling (flipping the crystal axis orientation by 180° every characteristic length), which introduces an additional momentum component (wavenumber kqpM) to the phase-matching condition.
  • QPM quasi -phase-matching
  • the indices of refraction of nonlinear optical materials are temperature-dependent. Additionally, the characteristic length (and therefore the phase-matching) of periodic poling changes due to the thermal expansion of the waveguide. Entanglement sources in practical implementations typically need fine control about an often quite high temperature, e.g. 100 °C, which requires bulky, high-power temperature controllers. Some environments, such as aboard drones or satellites, require strict limitations on size, weight, and power (SWaP). It is therefore prudent to design a compact down-conversion device capable of operating at a broader range of temperatures while maintaining the highest possible efficiencies. This eliminates the need for powerful temperature controllers and dramatically reduces the SWaP. No purposeful design of a periodically poled waveguide for broad temperature range down-conversion exists.
  • PPLN Periodically poled lithium niobate
  • T2 higher temperature
  • Tl lower temperature
  • Temperature differential to correct manufacturing errors Controlling the temperature differential between the two PPLN regions can help stabilize the temperature-dependent intensity response of the waveguide.
  • the thermal response curve is corrected with a constant temperature differential of 1.9°C between the two regions. This technique does not involve controlling the temperature of the entire waveguide, but rather just the difference in temperature between the two regions.
  • the corrective temperature differential is small, and therefore only requires small, lightweight, and low-power solutions (putting us on a path toward realizing a low-SWaP SPDC source).
  • the efficiency scales as the square of the length of the crystal (L 2 ) and effectively two crystals of length L/2 are being used, which causes the factor of 4 loss in efficiency of the two- region waveguide. It is possible to further increase temperature bandwidth by using additional regions. However, the bandwidth increases become smaller, and the efficiency scaling continues as 1/n 2 where n is the number of regions. Any inaccuracies in the poling periods in three-region waveguides become harder to correct with temperature differences, furthering the idea that having more than two regions is an impractical design. The dramatic increase predicted in the two-region waveguide’s operating temperature bandwidth has space-based and terrestrial real- world applications.
  • Example 4 Temperature-insensitive source for entangled time-frequency quantum photonic states
  • Described herein is a method for reducing the temperature sensitivity for spontaneous parametric down conversion (SPDC) suitable for generating entangled timefrequency quantum photonic states in the telecommunication band at a wavelength of 1550 nm.
  • SPDC spontaneous parametric down conversion
  • Specific design examples are presented using periodically-poled LiNbCh waveguides, which are commercially available and have a high second-order nonlinear coefficient that improves the overall device efficiency.
  • One method uses two distinct poling regions, each with a poling period selected for phase-matching at different temperatures. The temperature bandwidth is increased from ⁇ 5°C to ⁇ 17°C using this approach, while only reducing the overall efficiency of the process by a factor of 4.
  • the bandwidth is large enough so that controlling the overall temperature of the nonlinear crystal is likely not needed in a laboratory environment or can be achieved using a low size, weight, and power temperature controller design for field-deployed sources.
  • To improve the stability of the design it is proposed to use a differential heating method where only the difference in the temperature is stabilized.
  • the differential temperature stabilization method requires a smaller, lighter weight heater and lower power than other approaches, thus greatly simplifying the overall design. Additionally, it is shown that the system is less sensitive to fluctuations in the pump laser’s wavelength for the two-region approach. Finally, the design is generalized to multiple poling regions.
  • SPDC spontaneous parametric down conversion
  • Waveguide SPDC sources are of great current interest because they confine both the pump and generated pairs, thereby greatly increasing the overall device efficiency and lowering the required pump power. Designing the waveguide is substantially simplified if all waves have the same state of polarization. This polarization configuration lends itself to time-frequency entangled states (N Gisin et al. Nature Photon. 2007, 1, 165), where the conjugate variables are the time-of-arrival and frequency (energy) of the photons. Here, a focus is on methods for generating these states that are more robust to changes in the device temperature.
  • phase-matching can be achieved by adjusting the direction of propagation of the pump, signal, and idler waves with respect to the crystalline axes (so-called angle tuning). Another approach is to take advantage of the temperature dependence of the index of refraction of the material (temperature tuning). Depending on the wavelengths of the pump, signal, and idler waves, it is not always possible to achieve phase-matching. In some of these cases, it is possible to periodically invert the direction of the crystal axis to achieve what is known as phase-matching by periodic poling (MM Fejer et al. IEEE J. Quantum Electron. 1992, 28, 2631).
  • the devices and methods described herein is to alter a traditional periodically-poled waveguide to instead include two or more regions of different poling periods (/I) chosen for achieving phase-matching at different temperatures, which broadens the temperature bandwidth.
  • the usual one-region design is illustrated in Figure 5A and a two-region design is shown in Figure 5B.
  • the underlying principle of the design herein relies on a trade-off between phase matching at more temperatures, shortening the interaction length where a certain wavelength is down-converted most efficiently, and making combinations of the spectra from each different poling region coherent. This is discussed further in below, where incoherences due to manufacturing errors is discussed.
  • the Results section illustrates the efficiency advantage that two-region waveguides have over a range of ambient temperatures.
  • the correction of manufacturing error using a differential heating design is discussed below.
  • how the relative efficiency vs. ambient temperature curve changes for pump wavelength detuning, and its implications for the additional efficacy of the two-region waveguide approach for full system temperature insensitivity is discussed below.
  • the extension of this technique to additional poling periods with a few different techniques for altering them across the waveguide is examined.
  • the trade-off between the magnitude of nonlinearity and temperature bandwidth for different phase-matching configurations, specifically for LiNbCh is discussed.
  • the temperature-dependent refractive index (Bartnick et al. Phys. Rev. Appl. 2021, 15, 024028) and the thermal expansion of the grating using a thermal expansion coefficient of 7.5 x 10' 6 along a direction perpendicular to the crystalline “c” axis (https://www.bostonpiezooptics.com/lithium-niobate), that is, along the direction of propagation of the light in the waveguide, are considered.
  • One key concept of the design herein is to adjust the poling period along the length of the crystal so that different regions are phase-matched at different temperatures. Thus, there is always one region that will contribute to the SPDC process at some temperature.
  • a downside of this approach is that the effective length of the interaction region is less than the L, thereby reducing the efficiency. For future reference, the efficiency scales as L 2 for an ideal SPDC interaction.
  • the SPDC fields must add constructively between the two regions, requiring precise control over the relative poling periods between the regions.
  • the first case using a single poling period blue line
  • the ripples in the efficiency curve can be reduced by using more step regions, using a continuous linear chirp in the poling period, apodizing the grating, etc.
  • these approaches come at an increased manufacturing cost but may be worthwhile in some designs where a flat efficiency curve is an important metric. These points are discussed more below.
  • Another approach is to adjust the pump laser power as the temperature changes, thus reducing the variation in down-converted photon pair production of the overall system.
  • Compensating a manufacturing error using a differential temperature The shape of the efficiency curve is sensitive to small errors in the relative poling period between the two regions because there is interference from the generated SPDC fields in the two regions.
  • a second innovation is described to compensate for such errors by making a small adjustment to the temperature difference T between the regions. This technique exploits a combination of the thermal expansion of the crystal along the direction the light propagates alongside the temperature dependence of the refractive indices.
  • Figure 7A shows the efficiency curve for the two-region case when the poling period in the second region is 18.950 mm when the temperature is 30.8°C. This is a 6.3 nm error in the poling period.
  • the efficiency curve is clearly distorted in comparison to the ideal case shown in Figure 5A- Figure 5B when the temperature is uniform along the crystal. This is a case of incoherent addition of the efficiency curves for the two regions and is an important example of the sensitivity of their interaction with one another.
  • the overall temperature of the crystal does not need to be controlled, but only the temperature difference of the two regions. Furthermore, T is small, which will only require a small, lightweight, and low power temperature controller to maintain a relatively flat efficiency curve over a wide overall temperature range.
  • Sensitivity to pump wavelength detuning Lasers typically have a finite spectral width and a change in wavelength with temperature due to temperature dependent changes in the lasing medium, thermal expansion/contraction of the resonator cavity, or both. Therefore, reducing the periodically-poled waveguide efficiency’s sensitivity to changes in the pump laser’s wavelength and reducing the temperature sensitivity of the crystal for efficient SPDC are of similar interest. The former is focused on here.
  • a typical spectral tuning rate over temperature for semiconductor lasers in the visible wavelength range is about 0.2-0.3 nm/°C. In Figure 9, this corresponds to a full width at half maximum pump wavelength detuning bandwidth of approximately 1-2 °C and about 3-5 °C for one- and two-region waveguides, respectively.
  • There are designs that mitigate this temperature sensitivity at the source such as incorporating a Bragg grating, as is done in a distributed- feedback (DFB) laser.
  • DFB distributed- feedback
  • phase-matching temperature of different regions along length of the waveguide were chosen. For example, the authors looked at altering the phase-matching temperature of each region according to a Gaussian function, such that the first and last regions are phase matched to the lowest temperatures and the middle regions to the highest temperatures. The authors also looked at linearly increasing the phase-matching temperature, as well as altering it according to a tangent curve.
  • Figure 10 shows the relative efficiency of a ten-region waveguide with phase-matching temperatures that vary linearly, as a tangent and Gaussian functions.
  • the regions’ efficiency curves add more coherently over the different regions for the case of linearly increasing phase-matching temperature, so it has the broadest temperature bandwidth. For this method, the full width at half maximum temperature bandwidth is about 40 °C, which is over a two-fold improvement over the findings for an optimal two-region waveguide and approximately an eightfold improvement over a traditional uniformly poled waveguide.
  • a longer waveguide sharpens the efficiency peaks over temperature and lowers maximum efficiencies due to more destructive interference over the longer interaction length L.
  • the additional length can compensate for lower efficiencies caused by greater separation between the efficiency curves for different poling periods.
  • the intensity of photon pairs generated scales as L 2 . Therefore, if a flat efficiency response to changes in temperature is required for a given application, the use of a longer waveguide is recommended.
  • Figure 12 shows the relative efficiency curves of waveguides with 3, 10, 50, and 100 regions. Each has a linearly increasing phase-matching temperature from 15 to 35 °C.
  • phase-matching configuration used in the simulations herein was the Type 0 eee (extraordinarily polarized pump, signal, and idler photons, respectively). This choice is both practical and customary - the eee interaction in lithium niobate has a particularly large effective second-order nonlinear susceptibility d e ff, which is equal to half the sum of nonzero elements of the second-order nonlinear susceptibility % (2) after projecting the three interacting photons onto their corresponding polarization state.
  • deir for the eee interaction in lithium niobate is about a factor of ten greater than that of the Type 0 ooo interaction, and about a factor of five greater than that of the Type II oeo interaction.
  • the down- converted photon pair production rate scales as den 2 , so the Type 0 eee produces 100 times more photon pairs than Type 0 ooo for a given pump power.
  • the relative efficiency curves over temperature for these three phase-matching configurations are shown in Figure 13A- Figure 13B.
  • Example 5 Temperature-insensitive source for entangled time-frequency quantum photonic states
  • Quantum photonic entangled states are a resource for quantum information science, including communication and sensing applications; timefrequency states are insensitive to polarization disturbances, can access a high-dimensional Hilbert space (N Gisin et al. Nature Photon. 2007, 1, 165).
  • Periodic poling to achieve phase matching Periodic poling to achieve phase matching.
  • Periodic poling to achieve phase matching is shown in Figure 5 A.
  • lk 27t[(w P ump - ( «signai -Hidier)/2)/Xpump-l//wA]
  • L is the crystal length
  • //puiTip, ⁇ signal, and //idler are the index of refraction at the pump, signal, and idler wavelengths, respectively
  • m is the order of the interaction
  • A is the poling period.
  • Phase matching temperature sensitivity An example for lithium niobate is shown in Figure 4A- Figure 4B.
  • SPDC efficiency for a 2- cm-long crystal is shown in Figure 15.
  • Temperature must be stabilized. Typical means for stabilizing the temperature include, but are not limited to, crystal clips, PPLN ovens, and temperature controllers, however the system typically consumes a power of many Watts.
  • Temperature tolerance using two poling regions The temperature tolerance using two poling regions is shown in Figure 6 (poling periods were 18.990 pm and 8.956 pm, a 34 nm difference). Each region has half the length, and conversion efficiency scales at (length) 2 .
  • FIG 9 illustrates the sensitivity to change in pump wavelength and bandwidth.
  • the single region system is very a narrow band, such that the laser needs to be stabilized to ⁇ 0.1 nm. Volume holographic grating stabilization can be used.
  • Figure 9 also shows that using two poling regions helps with the pump bandwidth.
  • Nonlinear crystals used for down conversion are temperature sensitive. Typical approach is a bulky and power-hungry heater. A temperature-insensitive device was realized using two or more poling regions. The most temperature sensitive device might be the laser (if pumping with a diode laser).
  • Example 1 A periodically poled waveguide comprising: a first poling region having a first poling period; and a second poling region having a second poling period; wherein the first poling period is phase matched at a first temperature and the second poling period is phase matched at a second temperature, the first poling period being different than the second poling period such that the first temperature is different than the second temperature.
  • Example 2 The periodically poled waveguide of any examples herein, particularly example 1, wherein the periodically poled waveguide comprises barium borate, barium titanate, bismuth germanate, cadmium zinc telluride, cesium lithium borate, gallium(II) selenide, lithium iodate, lithium niobate (LiNbCh), lithium tantalate, lithium triborate, Nd:YCOB (Nd-doped YCOB, Nd:YCa4O(BO3)3), potassium aluminum borate, potassium dideuterium phosphate, potassium niobate, potassium titanyl phosphate, tellurium dioxide, terbium gallium garnet, yttrium iron garnet, or a combination thereof.
  • the periodically poled waveguide comprises barium borate, barium titanate, bismuth germanate, cadmium zinc telluride, cesium lithium borate, gallium(II) selenide, lithium iodate, lithium niobate (LiN
  • Example 3 The periodically poled waveguide of any examples herein, particularly example 1 or example 2, wherein the periodically poled waveguide comprises LiNbCh.
  • Example 4 The periodically poled waveguide of any examples herein, particularly examples 1-3, wherein the periodically poled waveguide comprises LiNbCh doped with a dopant.
  • Example 5 The periodically poled waveguide of any examples herein, particularly examples 1-4, wherein the periodically poled waveguide consists essentially of LiNbCh.
  • Example 6 The periodically poled waveguide of any examples herein, particularly examples 1-5, wherein the periodically poled waveguide consists of LiNbCh.
  • Example 7 The periodically poled waveguide of any examples herein, particularly examples 1-6, wherein the periodically poled waveguide consists essentially of the first poling region and the second poling region.
  • Example 8 The periodically poled waveguide of any examples herein, particularly examples 1-7, wherein the periodically poled waveguide consists of the first poling region and the second poling region.
  • Example 9 The periodically poled waveguide of any examples herein, particularly example 8, wherein the periodically poled waveguide has a total length, the first poling region has a first length, and the second poling region has a second length, the first length and the second length combining to provide the total length.
  • Example 10 The periodically poled waveguide of any examples herein, particularly example 9, wherein the first length and the second length are the same.
  • Example 11 The periodically poled waveguide of any examples herein, particularly example 9 or example 10, wherein the temperature bandwidth of the device is increased to 17°C relative to a temperature bandwidth of 5°C for similar device consisting of a single poling region.
  • Example 12 The periodically poled waveguide of any examples herein, particularly examples 1-6, wherein the periodically poled waveguide further comprises a third poling region having a third poling period, the third poling period being phase matched at a third temperature, the third poling period being different than both the first poling period and the second poling period, such that the third temperature is different than both the first temperature and the second temperature.
  • Example 13 The periodically poled waveguide of any examples herein, particularly example 12, wherein the periodically poled waveguide comprises one or more additional poling regions, each of the one or more additional poling regions having a poling period that is phase matched a temperature, wherein each of the poling periods is different than each other such that each phase matched temperature is different than each other.
  • Example 14 The periodically poled waveguide of any examples herein, particularly example 12 or example 13, wherein the total number of poling regions in the periodically poled waveguide is 3 or more, 4 or more, 5 or more, 10 or more, 25 or more, 50 or more, or 100 or more.
  • Example 15 The periodically poled waveguide of any examples herein, particularly examples 1-14, wherein the periodically poled waveguide is monolithic.
  • Example 16 The periodically poled waveguide of any examples herein, particularly examples 1-14, wherein the periodically poled waveguide is not monolithic.
  • Example 17 The periodically poled waveguide of any examples herein, particularly example 16, wherein each of the poling regions comprises a separate crystal, each of the crystals being separated from a neighboring crystal by a gap, which together form the periodically poled waveguide.
  • Example 18 The periodically poled waveguide of any examples herein, particularly examples 1-17, the periodically poled waveguide is less temperature sensitive relative to a waveguide consisting of a single poling region.
  • Example 19 The periodically poled waveguide of any examples herein, particularly examples 1-18, wherein the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is increased relative to the temperature bandwidth of a waveguide consisting of a single poling region.
  • Example 20 The periodically poled waveguide of any examples herein, particularly examples 1-19, wherein the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is increased by a factor of two or more (e.g., three or more) relative to the temperature bandwidth of a waveguide consisting of a single poling region.
  • Example 21 The periodically poled waveguide of any examples herein, particularly examples 1-20, wherein the periodically poled waveguide has a temperature bandwidth, and the temperature bandwidth of the periodically poled waveguide is 5°C or more, 10°C or more, 15°C or more, 35°C or more, 40°C or more, 50°C or more, 75°C or more, 100°C or more, 150°C or more, or 180°C or more.
  • Example 22 The periodically poled waveguide of any examples herein, particularly examples 1-21, wherein: the periodically poled waveguide has a temperature bandwidth; during use, the periodically poled waveguide is operated at an operation temperature; and the periodically poled waveguide is configured such that the operation temperature is within the temperature bandwidth of the periodically poled waveguide.
  • Example 23 A device comprising the periodically poled waveguide of any examples herein, particularly examples 1-22.
  • Example 24 The device of any examples herein, particularly example 23, wherein the device further comprises a temperature controller.
  • Example 25 The device of any examples herein, particularly example 24, wherein the temperature controller is configured to stabilize the temperature differential between the first and second poling regions.
  • Example 26 The device of any examples herein, particularly example 24 or example 25, wherein the first poling region is a high-temperature region and the second poling region is a low-temperature region, and wherein the temperature controller is configured to stabilize the temperature of the high-temperature region relative to the low-temperature region.
  • Example 27 The device of any examples herein, particularly examples 23-26, wherein the device generates photon pairs via spontaneous parametric down conversion.
  • Example 28 The device of any examples herein, particularly example 27, wherein the photon pairs are entangled.
  • Example 29 The device of any examples herein, particularly examples 23-28, wherein the device generates entangled photon pairs via spontaneous parametric down conversion.
  • Example 30 The device of any examples herein, particularly examples 23-29, wherein the device generates a plurality of photons (e.g., two or more, three or more, or four or more) via spontaneous parametric down conversion.
  • a plurality of photons e.g., two or more, three or more, or four or more
  • Example 31 The device of any examples herein, particularly examples 23-30, wherein the device is a quantum information device.
  • Example 32 The device of any examples herein, particularly examples 23-31, wherein the device comprises a drone, a satellite, or a combination thereof.
  • Example 33 The device of any examples herein, particularly examples 23-32, wherein the device is configured for a terrestrial application.
  • Example 34 The device of any examples herein, particularly examples 23-33, wherein the device is configured for an extra-terrestrial application.
  • Example 35 A method of use of the periodically poled waveguide of any examples herein, particularly examples 1-22.
  • Example 36 The method of any examples herein, particularly example 35, wherein the method comprises using the periodically poled waveguide in the device of any examples herein, particularly examples 23-34.
  • Example 37 A method of use of the device of any examples herein, particularly examples 23-34.
  • Example 38 The method of any examples herein, particularly examples 35-37, wherein the method comprises using the periodically poled waveguide or device to generate photon pairs via spontaneous parametric down conversion.
  • Example 39 The method of any examples herein, particularly example 38, wherein the photon pairs are entangled.
  • Example 40 The method of any examples herein, particularly examples 35-39, wherein the method comprises using the periodically poled waveguide or device to generate entangled photon pairs via spontaneous parametric down conversion.
  • Example 41 The method of any examples herein, particularly examples 35-40, wherein the method comprises using the periodically poled waveguide or device to generate a plurality of photons (e.g., two or more, three or more, or four or more) via spontaneous parametric down conversion.
  • a plurality of photons e.g., two or more, three or more, or four or more
  • Example 42 The method of any examples herein, particularly examples 35-41, wherein the method comprises using the periodically poled waveguide or device in a quantum information application.
  • Example 43 The method of any examples herein, particularly examples 35-42, wherein the method comprises using the periodically poled waveguide or device in a drone, a satellite, or a combination thereof.
  • Example 44 The method of any examples herein, particularly examples 35-43, wherein the method comprises using the periodically poled waveguide or device in a terrestrial application.
  • Example 45 The method of any examples herein, particularly examples 35-44, wherein the method comprises using the periodically poled waveguide or device in an extra-terrestrial application.
  • Example 46 A method of making the periodically poled waveguide of any examples herein, particularly examples 1-22.
  • Example 47 A periodically-poled LiNbCh waveguide comprising: a first poling region; and a second poling region, wherein a poling period of the first poling region or the second poling region is phase matched at two different temperatures.
  • Example 48 The waveguide of any examples herein, particularly example 47, wherein a respective poling period of each of the first poling region and the second poling region is phase matched at two different temperatures.
  • Example 49 The waveguide of any examples herein, particularly example 47, wherein a temperature bandwidth is increased from about 5 °C to about 17 °C.
  • Example 50 The waveguide of any examples herein, particularly example 47, wherein the first poling region is a high-temperature region and the second poling region is a low- temperature region.
  • Example 51 The waveguide of any examples herein, particularly example 50, wherein only the first poling region is stabilized.
  • Example 52 The waveguide of any examples herein, particularly example 50, wherein a differential heating method is used for the waveguide.
  • Example 53 A waveguide and method as described herein.

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Abstract

Sont divulgués ici des guides d'ondes à polarisation périodique et leurs procédés de fabrication et d'utilisation. Dans certains exemples, l'objet divulgué concerne des dispositifs et des procédés pour réduire la sensibilité à la température d'une conversion descendante paramétrique spontanée. Par exemple, sont divulgués ici des guides d'ondes à polarisation périodique comprenant au moins deux régions de polarisation, chacune ayant une période de polarisation différente qui est mise en correspondance de phase à une température différente.
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US20050111775A1 (en) * 2003-08-21 2005-05-26 Vitaly Fridman Method and apparatus for a dynamically reconfigurable waveguide in an integrated circuit
US20050230386A1 (en) * 2004-04-16 2005-10-20 Matsushita Electric Industrial Co., Ltd. Microwave baking furnace
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US20050230386A1 (en) * 2004-04-16 2005-10-20 Matsushita Electric Industrial Co., Ltd. Microwave baking furnace
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