WO2023284370A1 - Folding-type mach-zehnder modulator - Google Patents

Abstract

A folding-type Mach-Zehnder modulator, comprising: a light splitting element (210), which comprises a first input end (211), a first output end (212) and a second output end (213); a light combination element (220), which comprises a second input end (221), a third input end (222) and a third output end (223); a first waveguide arm (310) and a second waveguide arm (320), which are made of an electro-optic material and are in a folded state as a whole, wherein the first waveguide arm (310) and the second waveguide arm (320) integrally intersect in each turning area (102), the first waveguide arm (310) is connected to the first output end (212) and the second input end (221), and the second waveguide arm (320) is connected to the second output end (213) and the third input end (223); and a radio-frequency electrode, which comprises a first ground electrode (410), a first signal electrode (430) and a second ground electrode (420) which are in a folded state as a whole and are sequentially arranged without intersections, wherein in each radio-frequency modulation area (101), the first ground electrode (410) and the first signal electrode (430) are configured to apply a radio-frequency voltage to the first waveguide arm (310), and the second ground electrode (420) and the first signal electrode (430) are configured to apply a radio-frequency voltage to the second waveguide arm (320). By means of the folding-type Mach-Zehnder modulator, where the performance requirement of a device is satisfied, the miniaturized design of the device can be realized.

Description

Folded Mach-Zehnder modulator

Cross References to Related Applications

This application claims the priority of the invention patent application filed on July 16, 2021 with the application number 202110804468.6 and the application name "Folded Mach-Zehnder Modulator". The disclosure of the claimed priority of this application is incorporated by reference in its entirety This article.

technical field

The present disclosure relates to the technical field of optical communication, in particular to a folded Mach-Zehnder modulator.

Background technique

In recent years, with the rapid development of emerging network applications such as the Internet of Things, unmanned driving, telemedicine, and distance education, higher requirements have been put forward for high-speed and large-capacity communication technologies. Optical communication has achieved rapid development in the direction of high-speed and large-capacity communication due to its characteristics of large bandwidth, high reliability, low cost, and strong anti-interference ability. How to load high-speed electrical signals onto optical carriers is a core research content.

The electro-optic modulator is a modulator based on the electro-optic effect of electro-optic materials. The electro-optic effect means that when a voltage is applied to an electro-optic material such as lithium niobate crystal, gallium arsenide crystal or lithium tantalate crystal, the refractive index of the electro-optic material will change, which in turn causes the characteristics of the light wave passing through the electro-optic material to change. . Using the electro-optic effect, the modulation of optical signal parameters such as phase, amplitude, intensity, and polarization state can be realized.

The Mach-Zehnder modulator is a kind of electro-optic modulator, which divides the input optical signal into two branch optical signals, so that they enter two waveguide arms respectively. The two waveguide arms are made of electro-optic materials, and their refractive index varies with varies with modulation voltage. The change of the refractive index of the waveguide arm will cause the phase change of the branch optical signal. Therefore, the output of the two branch optical signals is an interference signal whose intensity varies with the modulation voltage. In short, the Mach-Zehnder modulator can achieve modulation of different sidebands by controlling the modulation voltage applied to the two waveguide arms. Mach-Zehnder modulator, as a device that converts electrical signals into optical signals, is one of the common core devices in optical interconnection, optical computing, and optical communication systems.

With the increasingly urgent demand for high-speed and large-capacity communication technology, higher requirements are put forward for the device performance and device size of the Mach-Zehnder modulator.

Contents of the invention

An embodiment of the present disclosure provides a folded Mach-Zehnder modulator, including N radio frequency modulation areas extending along the length direction and N-1 turning areas, N≥2, the folded Mach-Zehnder modulator includes: a light splitting element, It includes a first input end, a first output end and a second output end; an optical combination element includes a second input end, a third input end and a third output end; the first waveguide arm and the second waveguide arm are made of electro-optic material And the overall shape is folded, the first waveguide arm and the second waveguide arm intersect integrally in each turning area, the first waveguide arm connects the first output end and the second input end, the second waveguide arm connects the second output end and the third The input terminal; and, the radio frequency electrode, including the first ground electrode, the first signal electrode and the second ground electrode which are folded and arranged in sequence without crossing, and in each radio frequency modulation area, the first ground electrode and the first signal electrode The second ground electrode and the first signal electrode are configured to apply a radio frequency voltage to the second waveguide arm.

In some embodiments, the first waveguide arm and the second waveguide arm intersect vertically in one piece at each turning region.

In some embodiments, the first ground electrode, the first signal electrode and the second ground electrode are bent in a concentric arc shape in the turning area.

In some embodiments, the first waveguide arm and the second waveguide arm are synchronized with the turns of the first ground electrode, the first signal electrode, and the second ground electrode; or, the first waveguide arm and the second waveguide arm are compared to the first ground electrode The turns of the electrode, the first signal electrode and the second ground electrode lag; or, the turns of the first waveguide arm and the second waveguide arm lead compared to the turns of the first ground electrode, the first signal electrode and the second ground electrode.

In some embodiments, the folded Mach-Zehnder modulator includes a substrate, an isolation layer, a waveguide layer, an electrode layer, an insulating material layer, and a bridge layer arranged in sequence, wherein the first waveguide arm and the second waveguide arm are located between the waveguide layer; a part of the first signal electrode is located in the electrode layer, and a part is located in the bridge layer, and the part of the first signal electrode located in the bridge layer is electrically connected with the part of the first signal electrode located in the electrode layer, and is perpendicular to the substrate direction, the part of the first signal electrode located on the bridge layer overlaps with the first waveguide arm and the second waveguide arm.

In some embodiments, a part of the first ground electrode is located on the electrode layer, and a part is located on the bridge layer, and the part of the first ground electrode located on the bridge layer is electrically connected to the part of the first ground electrode located on the electrode layer. In the direction of the substrate, the part of the first ground electrode located on the bridge layer overlaps with the first waveguide arm and the second waveguide arm.

In some embodiments, a part of the second ground electrode is located on the electrode layer, and a part is located on the bridge layer, and the part of the second ground electrode located on the bridge layer is electrically connected to the part of the second ground electrode located on the electrode layer, vertically In the direction of the substrate, the part of the second ground electrode located on the bridge layer overlaps with the first waveguide arm and the second waveguide arm.

In some embodiments, the first ground electrode is located on the electrode layer, and in a direction perpendicular to the substrate, the first ground electrode does not overlap with the first waveguide arm and the second waveguide arm.

In some embodiments, a part of the first ground electrode is located on the electrode layer, and a part is located on the bridge layer, and the part of the first ground electrode located on the bridge layer is electrically connected to the part of the first ground electrode located on the electrode layer. In the direction of the substrate, the part of the first ground electrode located on the bridge layer does not overlap with the first waveguide arm and the second waveguide arm.

In some embodiments, the second ground electrode is located on the electrode layer, and in a direction perpendicular to the substrate, the second ground electrode does not overlap with the first waveguide arm and the second waveguide arm.

In some embodiments, a part of the second ground electrode is located on the electrode layer, and a part is located on the bridge layer, and the part of the second ground electrode located on the bridge layer is electrically connected to the part of the second ground electrode located on the electrode layer, vertically In the direction of the substrate, the part of the second ground electrode located on the bridge layer does not overlap with the first waveguide arm and the second waveguide arm.

In some embodiments, the waveguide layer is a ridge waveguide layer, including a slab layer and a ridge layer located on the slab layer, the first waveguide arm and the second waveguide arm are located on the ridge layer, and the electrode layer is formed on the slab layer away from the substrate. bottom surface.

In some embodiments, the waveguide layer is a ridge waveguide layer, including a slab layer and a ridge layer on the slab layer, the first waveguide arm and the second waveguide arm are located on the ridge layer, the slab layer has grooves, and the electrode layer is embedded In the groove.

In some embodiments, the waveguide layer is a ridge layer including a first waveguide arm and a second waveguide arm, and the electrode layer is formed on the surface of the isolation layer away from the substrate.

In some embodiments, the folded Mach-Zehnder modulator further includes: a phase compensation modulation module disposed between the radio frequency electrode and the light splitting element, or between the radio frequency electrode and the light combining element.

It should be understood that what is described in this section is not intended to identify key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will be readily understood through the following description.

Description of drawings

Further details, features and advantages of the present disclosure are disclosed in the following description of exemplary embodiments with reference to the accompanying drawings in which:

Fig. 1 is a simplified structural top view of a traditional Mach-Zehnder modulator;

2 is a structural top view and a partial structural cross-sectional view of a folded Mach-Zehnder modulator according to some exemplary embodiments of the present disclosure;

Fig. 3 is a structural top view and a partial structural cross-sectional view of a folded Mach-Zehnder modulator according to other exemplary embodiments of the present disclosure;

Fig. 4 is a structural top view and a partial structural cross-sectional view of a folded Mach-Zehnder modulator according to some other exemplary embodiments of the present disclosure;

5 is a structural top view and a partial structural cross-sectional view of a folded Mach-Zehnder modulator according to still some exemplary embodiments of the present disclosure; and

Fig. 6 is a structural top view and a partial structural cross-sectional view of a folded Mach-Zehnder modulator according to some other exemplary embodiments of the present disclosure.

detailed description

In the following, only some exemplary embodiments are briefly described. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present disclosure. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature and not restrictive.

As shown in FIG. 1 , it is a schematic structural diagram of a traditional Mach-Zehnder modulator. Ideally, the two waveguide arms 02 of the Mach-Zehnder modulator 001 are absolutely identical. When the Mach-Zehnder modulator 001 is not working, the electro-optic effect does not occur in the two waveguide arms 02, and the input light is divided into two branch optical signals after passing through the optical splitting element 01, and the two branch optical signals pass through a waveguide arm 02 respectively. The rear phases are still the same, therefore, the coherence enhancement signal of the two branch optical signals will be output from the light combining element 05 . When the Mach-Zehnder modulator 001 is working, the modulation electrode 04 (for example, including the signal electrode 040, the first ground electrode 041 and the second ground electrode 042) applies a modulation voltage to the two waveguide arms 02, and the two branch optical signals pass through a The phase difference behind the waveguide arm 02 can be an odd or even multiple of Π. When the phase difference is an even multiple of Π, the light combining element 05 outputs the coherence enhancement signal of the two branch optical signals. When the phase difference is an odd multiple of Π, the optical combination Element 05 outputs the coherent cancellation signal of the two branch optical signals.

It can be seen from the figure that the structure of this traditional Mach-Zehnder modulator is slender, its length is usually on the order of millimeters or centimeters, and its width is usually on the order of hundreds of microns. In addition, in order to minimize the The driving voltage will also be designed to increase the length of the two waveguide arms. Although the width of the Mach-Zehnder modulator is small, its overall size is still mainly determined by the length. Therefore, how to realize the miniaturization design of the device without affecting the performance of the device is an urgent problem for those skilled in the art. technical problem.

The embodiment of the present disclosure provides a folded Mach-Zehnder modulator, which can realize the miniaturization design of the device on the premise of meeting the performance requirements of the device.

As shown in Figure 2, some embodiments of the present disclosure provide a folded Mach-Zehnder modulator 1, including N radio frequency modulation regions 101 extending along the length direction and N-1 turning regions 102, where N≥2 (In this embodiment, it is represented by N=2). The main structure of the folded Mach-Zehnder modulator 1 includes a light splitting element 210, a light combining element 220, a first waveguide arm 310, a second waveguide arm 320, and a radio frequency electrode, wherein the radio frequency electrode includes a first ground electrode 410, a first signal electrode 430 and the second ground electrode 420 .

The light splitting element 210 includes a first input end 211 , a first output end 212 and a second output end 213 , and the light combining element 220 includes a second input end 221 , a third input end 222 and a third output end 223 . The first waveguide arm 310 is connected to the first output end 212 and the second input end 221 , and the second waveguide arm 320 is connected to the second output end 213 and the third input end 223 . The material of the first waveguide arm 310 and the second waveguide arm 320 is electro-optic material and is folded as a whole, and the first waveguide arm 310 and the second waveguide arm 320 intersect integrally in each turning area 102 .

In the embodiment of the present disclosure, the specific structural form of the light splitting element 210 is not limited, it includes at least one input end and two output ends, for example, it may be a light splitting element with one input and two outputs. The specific structural form of the light combining element 220 is not limited, it includes at least two input ports and one output port, for example, it may be a light combining element with two inputs and one output or a light combination element with two inputs and three outputs, and so on.

The first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 are folded as a whole and arranged in sequence without crossing. As shown in FIG. 2 , the radio frequency electrodes (that is, the first ground electrode 410, the first signal electrode 430 and the second ground electrode 420 as a whole) overlap at least partially with the first waveguide arm 310 and the second waveguide arm 320 in the length direction, each An overlapping area is a radio frequency modulation area 101. In the radio frequency modulation area 101, the first ground electrode 410 and the first signal electrode 430 are configured to apply a radio frequency voltage to the first waveguide arm 310, and the second ground electrode 420 and the first signal electrode 430 are configured to apply radio frequency voltage to the second waveguide arm 320. Voltage.

In the embodiment of the present disclosure, N is a natural number, and N≥2. It can be understood that when the number of radio frequency modulation regions 101 is an even number (for example, as shown in FIG. 2, when N=2), the light splitting element 210 and the light combining element 220 Set on the same side of the folded Mach-Zehnder modulator 1, when the number of radio frequency modulation regions 101 is an odd number (for example, as shown in FIG. Opposite side of Mach-Zehnder modulator 1.

The folded Mach-Zehnder modulator 1 provided by the embodiment of the present disclosure can greatly reduce the size in the length direction compared with the traditional Mach-Zehnder modulator due to the folded design. In order to obtain better performance of the device, the length of the waveguide arm can be designed to increase according to the requirement, and the overall length of the device is less affected.

Both the first waveguide arm 310 and the second waveguide arm 320 are made of electro-optical materials, such as lithium niobate, lithium tantalate, or potassium titanyl phosphate. Since the refractive index change of the electro-optical material is related to the direction of the electric field, if the first waveguide arm 310 and the second waveguide arm 320 are not crossed in the turning area 102, then, in the next radio frequency modulation area 101 after the turning area 102, the two waveguides The arms will be in opposite electric fields so that the resulting phase differences cancel each other out. Therefore, the first waveguide arm 310 and the second waveguide arm 320 need to be designed as a cross structure in the turning area 102 to ensure that the direction of the electric field where the two waveguide arms are located in each radio frequency modulation area 101 remains unchanged. In FIG. 2, the electric field formed by the first signal electrode 430 and the first ground electrode 410, and the electric field formed by the first signal electrode 430 and the second ground electrode 420 are respectively shown by the dotted arrows in the figure. It can be seen that , the direction of the electric field of each waveguide arm in each radio frequency modulation region 101 is the same.

In the embodiment of the present disclosure, the first waveguide arm 310 and the second waveguide arm 320 are made of the same material and are integrally intersected in each turning area 102 , which can reduce light transmission in the first waveguide arm 310 and the second waveguide arm 320 respectively. The transmission loss and the reduction of crosstalk between each other are beneficial to improve the performance of the device. The integral cross structure of the first waveguide arm 310 and the second waveguide arm 320 can be formed through an etching process of the waveguide layer.

As shown in FIG. 2 , in some embodiments, the first waveguide arm 310 and the second waveguide arm 320 each have a circular arc shape and intersect each other in each turning area 102 . As shown in Figure 3, the first waveguide arm 310 and the second waveguide arm 320 are vertically intersected in each turning area 102, so that at the intersection, the angle between any adjacent waveguide branches is 90 degrees, so that the waveguide Transmission interference between branches is minimized. Although the two waveguide arms intersect in the turning area 102, the propagation of light in the two waveguide arms is still roughly in accordance with the extension direction of the waveguide arms, which is slightly affected by the intersection structure and the transmission loss is small.

The present disclosure does not limit the cross shape of the first waveguide arm 310 and the second waveguide arm 320 to the above-mentioned embodiments, for example, in some embodiments, the first waveguide arm and the second waveguide arm can also be zigzag in each turning area cross.

As shown in Figure 2 and Figure 3, in this embodiment, the first ground electrode 410, the first signal electrode 430 and the second ground electrode 420 are bent in the shape of concentric arcs in the turning area 102, which is convenient for processing on the one hand, and on the other hand On the one hand, the loss of electrical transmission can be minimized. Of course, the present disclosure does not specifically limit this, and the first ground electrode, the first signal electrode and the second ground electrode may also be designed in other shapes in the turning area.

In the folded Mach-Zehnder modulator 1 of the embodiment of the present disclosure, along the transmission direction of light from the light splitting element 210 to the light combining element 220 (the overall shape is also folded), the first waveguide arm 310 and the second waveguide arm 320 are compared with the first waveguide arm 320 The turning settings of a ground electrode 410, the first signal electrode 430 and the second ground electrode 420 may be synchronous, lagging or leading.

The radio frequency electrode applies radio frequency voltage to the first waveguide arm 310 and the second waveguide arm 320 of the electro-optical material according to the electrical signal of the radio frequency circuit, so as to realize the phase modulation of the optical signal transmitted in the first waveguide arm 310 and the second waveguide arm 320 . However, due to the difference between the transmission rate of the optical field and the transmission rate of the electric field, the transmission rates of the two in the radio frequency modulation area 101 may be mismatched. Assuming that in the radio frequency modulation area, V _light >V _electricity , then, according to L/V _light +ΔL1/V _light =L/V _electricity , it can be obtained, ΔL1=(L/V _electricity- L/V _light )*V _light ; Assuming that in the _radio frequency modulation area, Vpower> _Vlight , then, according to L/Vpower+ _ΔL2 /Vpower=L/ _Vlight , _ΔL2 =(L/ _{Vlight -} L/Vpower)*Vpower can be obtained _. Therefore, the transmission rate of the light field and the electric field can be matched by designing ΔL1 or ΔL2, where V _electric is the transmission rate of the electric field, V _light is the transmission rate of the light field, L is the size of the radio frequency modulation area along the length direction, and ΔL1 is The dimension along the length direction of the turning area of the two waveguide arms when the turn lags behind the RF electrode, ΔL2 is the lengthwise dimension of the turn area of the radio frequency electrode when the turn lags behind that of the two waveguide arms. In the embodiment of the present disclosure, the above-mentioned difference in the transmission rate can be compensated by designing the turning sequence of the first waveguide arm 310 and the second waveguide arm 320 compared with the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 , to match the transmission of the light field and the electric field in the radio frequency modulation region 101 , thereby improving the device performance of the folded Mach-Zehnder modulator 1 .

As shown in FIG. 2 , the layer structure of the folded Mach-Zehnder modulator 1 in some embodiments of the present disclosure includes: a substrate 510, an isolation layer 520, a waveguide layer 530, an electrode layer 540, an insulating material layer 550 and an electrical Bridge layer 560. The waveguide layer 530 can be the ridge waveguide layer shown in the figure, including a flat layer and a ridge layer 531 located on the flat layer. The flat layer and the ridge layer 531 are an integral structure formed by etching, and the pattern of the electrode layer 540 is formed on the surface of the plate layer away from the substrate 510 .

In other embodiments of the present disclosure, the waveguide layer is a ridge waveguide layer, including a slab layer and a ridge layer located on the slab layer, the slab layer and the ridge layer are an integral structure formed by etching, and the first waveguide arm and the second waveguide arm are located on the ridge layer, the plate layer has patterned grooves, and the electrode layer is embedded in the grooves. In addition, the waveguide layer may not include a flat layer but only include a ridge layer, and the ridge layer includes a first waveguide arm and a second waveguide arm, so that the electrode layer can be formed on the surface of the isolation layer away from the substrate.

The first waveguide arm 310 and the second waveguide arm 320 are located on the ridge layer 531 , specifically some ridge patterns of the ridge layer 531 . In some embodiments, the multimode interference waveguide used for light splitting of the light splitting element 210 and the multimode interference waveguide used for light combining of the light combining element 220 are also located in the waveguide layer 530, specifically some ridges of the ridge layer 531 Convex pattern.

According to the number of radio frequency modulation regions 101 included in the folded Mach-Zehnder modulator 1, and the ratio of the first waveguide arm 310 and the second waveguide arm 320 to the first ground electrode 410, the first signal electrode 430 and the second ground electrode 420 The design of the specific structure of the folded Mach-Zehnder modulator 1 is also different for different design of the turning position, but they all need to satisfy: the intersection of the first waveguide arm 310 and the second waveguide arm 320 in the turning area 102, and the avoidance of the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 physically cross the first waveguide arm 310 and the second waveguide arm 320 .

The Mach-Zehnder modulators with different designs in the present disclosure will be further described in detail below.

As shown in FIG. 2 , in some embodiments, the first waveguide arm 310 and the second waveguide arm 320 are synchronized with the turning of the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 , and in the turning area 102 , The first waveguide arm 310 , the second waveguide arm 320 , the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 are curved according to their respective radii of curvature and start to turn and end to turn at the same time.

In this embodiment, a part of the first signal electrode 430 is located on the electrode layer 540, a part is located on the bridge layer 560, and the part located on the bridge layer 560 is electrically connected to the part located on the electrode layer 540, for example, through the via structure 551 electrical connection. In a direction perpendicular to the substrate 510 , the portion of the first signal electrode 430 located on the bridge layer 560 overlaps the first waveguide arm 310 and the second waveguide arm 320 . Wherein, the via structure is a plurality of through holes formed on the insulating material layer 550 .

Specifically, the first signal electrode 430 includes a first body portion 1 a located on the electrode layer 540 and a first bridge portion 1 b located on the bridge layer 560 and electrically connected to the first body portion 1 a through the via structure 551 . In this embodiment, the first body part 1a includes two strip-shaped electrode areas extending along the length direction, and the first bridge part 1b is curved. The whole of the first ground electrode 410 is located on the electrode layer 540 , and the whole of the second ground electrode 420 is located on the electrode layer 540 . In the direction perpendicular to the substrate 510, the first body part 1a has no overlap with the first waveguide arm 310 and the second waveguide arm 320, and the first bridge part 1b has overlap with the first waveguide arm 310 and the second waveguide arm 320. overlap, the first ground electrode 410 and the second ground electrode 420 do not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

Although the first bridge part 1b overlaps with the first waveguide arm 310 and the second waveguide arm 320 in the direction perpendicular to the substrate 510, since the first bridge part 1b overlaps with the first waveguide arm 310 and the second waveguide arm 310, the second The waveguide arms 320 are in different structural layers, therefore, there is no intersection in reality. The structural design of this embodiment is applicable to situations where N=2 or N≧3.

In other embodiments of the present disclosure, compared with the embodiment shown in FIG. 2 , the difference in structure is that the first ground electrode and the second ground electrode also adopt a bridge structure design. For example, the first ground electrode includes a second body part located on the electrode layer and a second bridge part located on the bridge layer and electrically connected to the second body part (for example, electrically connected through a via structure), and the second body part also includes There are two strip-shaped electrode areas extending along the length direction, and the second electric bridge part is curved. Similarly, the second ground electrode includes a third body part located on the electrode layer and a third bridge part located on the bridge layer and electrically connected to the third body part (for example, electrically connected through a via structure), and the third body part is also It includes two strip-shaped electrode areas extending along the length direction, and the third electric bridge part is curved. In this way, the impedance mismatch that may exist in the first ground electrode, the first signal electrode, and the second ground electrode can be improved, which is beneficial to further improving the performance of the device.

As shown in FIG. 3 , in some embodiments, N=2, the first waveguide arm 310 and the second waveguide arm 320 are synchronized with the turns of the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 .

In this embodiment, a part of the first signal electrode 430 is located on the electrode layer 540, and a part is located on the bridge layer 560, and the part of the first signal electrode 430 located on the bridge layer 560 and the part of the first signal electrode 430 located on the electrode layer 540 Some of the parts are electrically connected, for example, through the via structure 551 . A part of the first ground electrode 410 is located in the electrode layer 540, a part is located in the bridge layer 560, and the part of the first ground electrode 410 located in the bridge layer 560 is electrically connected with the part of the first ground electrode 410 located in the electrode layer 540, for example They are electrically connected through the via structure 551 . In the direction perpendicular to the substrate 510, the part of the first signal electrode 430 located on the bridge layer 560 and the part of the first ground electrode 410 located on the bridge layer 560 are connected to the first waveguide arm 310 and the second waveguide arm 320. There is overlap, and the second ground electrode 420 does not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

Specifically, the first signal electrode 430 includes a first body part 1a located on the electrode layer 540 and a first bridge part 1b located on the bridge layer 560 and electrically connected to the first body part 1a through a via structure 551. The first body The part 1a includes two strip-shaped electrode areas extending along the length direction, and the first bridge part 1b is curved. Similarly, the first ground electrode 410 includes a second body part 2a located on the electrode layer 540 and a second bridge part 2b located on the bridge layer 560 and electrically connected to the second body part 2a through a via structure 551, the second body The part 2a also includes two strip-shaped electrode areas extending along the length direction, and the second bridge part 2b is curved. Similarly, the second ground electrode 420 includes a third body part 3a located on the electrode layer 540 and a third bridge part 3b located on the bridge layer 560 and electrically connected to the third body part 3a through the via structure 551. The third body The part 3a also includes two strip-shaped electrode areas extending along the length direction, and the third bridge part 3b is curved. In the direction perpendicular to the substrate 510, the first body part 1a, the second body part 2a, and the third body part 3a do not overlap with the first waveguide arm 310 and the second waveguide arm 320, and the first bridge part 1b , the second bridge part 2b overlap with the first waveguide arm 310 and the second waveguide arm 320 , and the third bridge part 3b does not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

In some other embodiments, since the second ground electrode does not overlap with the first waveguide arm and the second waveguide arm, the second ground electrode may not be designed with a bridge structure, but may be entirely located on the electrode layer.

As shown in FIG. 4 , in some embodiments, N=2, the first waveguide arm 310 and the second waveguide arm 320 lag behind the turning of the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 , In the turning area 102, the first ground electrode 410, the first signal electrode 430, and the second ground electrode 420 are designed to be curved according to their respective curvature radii, and start turning and end turning at the same time, while the first waveguide arm 310 and the second waveguide arm 310 The arm 320 is then extended along the length direction for a certain period before turning.

The structure of this embodiment in the turning area 102 is the same as that of the embodiment shown in FIG. 3 . Specifically, the first signal electrode 430 includes a first body part 1a located on the electrode layer 540 and a first bridge part 1b located on the bridge layer 560 and electrically connected to the first body part 1a through a via structure 551. The first body The part 1a includes two strip-shaped electrode areas extending along the length direction, and the first bridge part 1b is curved. The first ground electrode 410 includes a second body part 2a located on the electrode layer 540 and a second bridge part 2b located on the bridge layer 560 and electrically connected to the second body part 2a through a via structure 551. The second body part 2a includes There are two strip-shaped electrode areas extending along the length direction, and the second bridge part 2b is curved. The second ground electrode 420 includes a third body part 3a located on the electrode layer 540 and a third bridge part 3b located on the bridge layer 560 and electrically connected to the third body part 3a through a via structure 551. The third body part 3a includes There are two strip-shaped electrode areas extending along the length direction, and the third bridge part 3b is curved. In the direction perpendicular to the substrate 510, the first body part 1a, the second body part 2a, and the third body part 3a do not overlap with the first waveguide arm 310 and the second waveguide arm 320, and the first bridge part 1b , the second bridge part 2b overlap with the first waveguide arm 310 and the second waveguide arm 320 , and the third bridge part 3b does not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

As shown in FIG. 5 , in some embodiments, N=2, the first waveguide arm 310 and the second waveguide arm 320 are ahead of the turning of the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 , In the turning area 102, the first waveguide arm 310 and the second waveguide arm 320 are first designed to turn according to their respective curvature radii, while the first ground electrode 410, the first signal electrode 430 and the second ground electrode 420 extend along the length direction. Turn after a while.

In this embodiment, a part of the first signal electrode 430 is located on the electrode layer 540, and a part is located on the bridge layer 560, and the part of the first signal electrode 430 located on the bridge layer 560 and the part of the first signal electrode 430 located on the electrode layer 540 Some of the parts are electrically connected, for example, through the via structure 551 . The first ground electrode 410 is entirely located on the electrode layer 540 . A part of the second ground electrode 420 is located in the electrode layer 540, a part is located in the bridge layer 560, and the part of the second ground electrode 420 located in the bridge layer 560 is electrically connected with the part of the second ground electrode 420 located in the electrode layer 540, for example They are electrically connected through the via structure 551 . In the direction perpendicular to the substrate 510, the part of the first signal electrode 430 located on the bridge layer 560 and the part of the second ground electrode 420 located on the bridge layer 560 are connected to the first waveguide arm 310 and the second waveguide arm 320. There is overlap, and the first ground electrode 410 does not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

Specifically, the first signal electrode 430 includes a first body part 1a located on the electrode layer 540 and a first bridge part 1b located on the bridge layer 560 and electrically connected to the first body part 1a through a via structure 551. The first body Part 1a includes two strip-shaped electrode areas extending along the length direction, and a curved strip-shaped electrode area, the first bridge part 1b includes two strip-shaped electric bridges extending along the length direction, and the two strip-shaped electrode areas The bridge electrically connects the first body part 1 a through the via structure 551 . The first ground electrode 410 is entirely located on the electrode layer 540 . The structure of the second ground electrode 420 is similar to that of the first signal electrode 430, including the third body part 3a located on the electrode layer 540 and the third electrical electrode located on the bridge layer 560 and electrically connected to the third body part 3a through the via structure 551. Bridge part 3b, the third body part 3a includes two strip-shaped electrode areas extending along the length direction, and a curved strip-shaped electrode area, the third bridge part 3b includes two strip-shaped electrode areas extending along the length direction Bridge, the two strip bridges are electrically connected to the third body part 3 a through the via structure 551 . In the direction perpendicular to the substrate 510, the first body part 1a and the third body part 3a do not overlap with the first waveguide arm 310 and the second waveguide arm 320, and the first bridge part 1b and the third bridge part 3b overlaps with the first waveguide arm 310 and the second waveguide arm 320 , and the first ground electrode 410 does not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

In some other embodiments of the present disclosure, the structure of the first signal electrode and/or the second ground electrode may also be designed in other forms. Taking the first signal electrode as an example, its first body part includes two strip-shaped electrode regions extending along the length direction but does not include a curved strip-shaped electrode region, and the first bridge part is curved as a whole and includes two sections In the part extending along the length, the two strip-shaped electrode regions are electrically connected through a curved first electric bridge part.

In some other embodiments, compared with the embodiment shown in FIG. 5 , the structural difference is that the first ground electrode also adopts a bridge structure design. For example, in order to improve the impedance mismatch that may exist in the first ground electrode, the first signal electrode, and the second ground electrode, the design of the first ground electrode is similar to that of the above-mentioned first signal electrode and the second ground electrode.

As shown in FIG. 6 , in some embodiments, N=3, the first waveguide arm 310 and the second waveguide arm 320 are synchronized with the turns of the first ground electrode 410 , the first signal electrode 430 and the second ground electrode 420 . Compared with the embodiment shown in FIG. 3 , in addition to the difference in the number of radio frequency modulation regions 101 and turning regions 102 , another main structural difference is that, in the direction perpendicular to the substrate 510 , the first signal electrode 430 , the second Both the first ground electrode 410 and the second ground electrode 420 overlap with the first waveguide arm 310 and the second waveguide arm 320 . However, since the turning radii of the first ground electrode 410 and the second ground electrode 420 differ greatly in different turning regions 102, in the direction perpendicular to the substrate 510, the first ground electrode 410 and the second ground electrode 420 are not Each turning area 102 overlaps with the first waveguide arm 310 and the second waveguide arm 320 . For example, as shown in FIG. 6, in the direction perpendicular to the substrate 510, in the first turning region 102, the first ground electrode 410 overlaps the first waveguide arm 310 and the second waveguide arm 320, and the second ground electrode 410 The electrode 420 does not overlap with the first waveguide arm 310 and the second waveguide arm 320; in the second turning area 102, the second ground electrode 420 overlaps with the first waveguide arm 310 and the second waveguide arm 320, while the first ground The electrode 410 does not overlap with the first waveguide arm 310 and the second waveguide arm 320 .

In this embodiment, a part of the first signal electrode 430 is located on the electrode layer 540 (such as the first main body part 1a in the figure), and a part is located on the bridge layer 560 (such as the first bridge part 1b in the figure), and the first signal electrode The part of 430 located on the bridge layer 560 is electrically connected to the part of the first signal electrode 430 located on the electrode layer 540 , for example, through the via structure 551 . A part of the first ground electrode 410 is located at the electrode layer 540 (as shown in the second body part 2a), a part is located at the bridge layer 560 (as shown in the second bridge part 2b), and the first ground electrode 410 is located at the bridge A portion of the layer 560 is electrically connected to a portion of the first ground electrode 410 located on the electrode layer 540 , for example, through the via structure 551 . A part of the second ground electrode 420 is located at the electrode layer 540 (as shown in the third body part 3a), a part is located at the bridge layer 560 (as shown in the third bridge part 3b), and the second ground electrode 420 is located at the bridge A portion of the layer 560 is electrically connected to a portion of the second ground electrode 420 located on the electrode layer 540 , for example, through the via structure 551 . In the direction perpendicular to the substrate 510, the part of the first signal electrode 430 located at the bridge layer 560, the part of the first ground electrode 410 located at the bridge layer 560, the part of the second ground electrode 420 located at the bridge layer 560 Parts overlap with the first waveguide arm 310 and the second waveguide arm 320, but the part of the first ground electrode 410 located on the bridge layer 560 and the part of the second ground electrode 420 located on the bridge layer 560 are not in each Each turning area 102 overlaps with the first waveguide arm 310 and the second waveguide arm 320 .

In the above embodiments of the present disclosure, the electrical connection between the electrode layer 540 and the bridge layer 560 is not limited to the via structure 551 through the insulating material layer 550 . For example, in other embodiments of the present disclosure, the insulating material layer may also include a plurality of block units disposed at the junction of the electrode layer and the bridge layer, and the bridge layer extends downward along the sidewall of the block unit to Electrically connected to the electrode layer.

In some embodiments of the present disclosure, the folded Mach-Zehnder modulator further includes: a phase compensation modulation module disposed between the radio frequency electrode and the light splitting element, or between the radio frequency electrode and the light combining element. The phase compensation modulation module is used to modulate the first waveguide arm and the second waveguide arm, thereby compensating the inherent phase difference of the two waveguide arms and improving the accuracy of the modulation output of the Mach-Zehnder modulator.

The specific type of the phase compensation modulation module is not limited, for example, it may be an electro-optic phase compensation modulation module based on the electro-optic effect, or a thermo-optic phase compensation modulation module based on the thermo-optic effect, and so on.

As shown in FIG. 6 , in some embodiments of the present disclosure, the phase compensation modulation module is an electro-optic phase compensation modulation module arranged between the radio frequency electrode and the light-combining element 220, including the third ground electrode 610, the third ground electrode 610, and the Two signal electrodes 630 and a fourth ground electrode 620, wherein the third ground electrode 610 and the second signal electrode 630 are configured to apply a bias voltage to the first waveguide arm 310, and the fourth ground electrode 620 and the second signal electrode 630 are configured to A bias voltage is applied to the second waveguide arm 320 .

The third ground electrode 610 , the second signal electrode 630 and the fourth ground electrode 620 can be fabricated synchronously during the fabrication process of the radio frequency electrodes, for example, located on the aforementioned electrode layer 540 .

In some embodiments, the phase compensation modulation module may also not be selected to be arranged as required.

To sum up, the folded Mach-Zehnder modulator provided by the embodiments of the present disclosure can realize the miniaturization design of the device on the premise of satisfying the performance requirements of the device, so that it can be more easily integrated into a hardware system.

It should be understood that in this specification the terms "central", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear" , "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial", " The orientation or positional relationship or size indicated by "radial direction", "circumferential direction" and so on are based on the orientation or positional relationship or size shown in the drawings, and these terms are used only for the convenience of description, not to indicate or imply the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and thus should not be construed as limiting the scope of the present disclosure.

In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only, and should not be interpreted as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first", "second" and "third" may explicitly or implicitly include one or more of these features. In the description of the present disclosure, "plurality" means two or more, unless otherwise specifically defined.

In this disclosure, terms such as "installation", "connection", "connection" and "fixation" should be interpreted in a broad sense, for example, it can be a fixed connection or a detachable connection unless otherwise clearly defined and limited. , or integrated; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection or an indirect connection through an intermediary, it can be the internal communication of two components or the interaction relationship between two components . Those of ordinary skill in the art can understand the specific meanings of the above terms in the present disclosure according to specific situations.

In the present disclosure, unless otherwise clearly stated and limited, a first feature being "on" or "under" a second feature may include direct contact between the first and second features, and may also include the first and second features Not in direct contact but through another characteristic contact between them. Moreover, the first feature being "above", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. "Below", "beneath" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

This specification provides many different embodiments or examples that can be used to implement the present disclosure. It should be understood that these different embodiments or examples are purely exemplary and are not intended to limit the protection scope of the present disclosure in any way. Those skilled in the art can conceive of various changes or substitutions on the basis of the disclosure content in the specification of the present disclosure, and these should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be defined by the appended claims.

Claims (15)

A folded Mach-Zehnder modulator, including N radio frequency modulation areas extending along the length direction and N-1 turning areas, N≥2, the folded Mach-Zehnder modulator includes: A light splitting element, including a first input terminal, a first output terminal and a second output terminal; A light-combining element, including a second input end, a third input end and a third output end; The first waveguide arm and the second waveguide arm are made of electro-optic material and are folded as a whole. The first waveguide arm and the second waveguide arm cross integrally at each turning area, and the first waveguide arm connects the first output end and the second input. end, the second waveguide arm is connected to the second output end and the third input end; and The radio frequency electrode includes the first ground electrode, the first signal electrode and the second ground electrode which are arranged in a folded shape without crossing in sequence. In each radio frequency modulation area, the first ground electrode and the first signal electrode are configured to face the first The waveguide arm applies a radio frequency voltage, and the second ground electrode and the first signal electrode are configured to apply a radio frequency voltage to the second waveguide arm. The folded Mach-Zehnder modulator according to claim 1, wherein the first waveguide arm and the second waveguide arm intersect vertically integrally at each turning region. The folded Mach-Zehnder modulator according to claim 1, wherein the first ground electrode, the first signal electrode and the second ground electrode are bent in a concentric arc shape in the turning area. The folded Mach-Zehnder modulator according to claim 1, wherein, the first waveguide arm and the second waveguide arm are synchronized with the turns of the first ground electrode, the first signal electrode and the second ground electrode; or the first waveguide arm and the second waveguide arm lag behind the turn of the first ground electrode, the first signal electrode and the second ground electrode; or The first waveguide arm and the second waveguide arm lead the turn of the first ground electrode, the first signal electrode and the second ground electrode. The folded Mach-Zehnder modulator according to claim 1, wherein, The folded Mach-Zehnder modulator includes a substrate, an isolation layer, a waveguide layer, an electrode layer, an insulating material layer and a bridge layer arranged in sequence, wherein, The first waveguide arm and the second waveguide arm are located in the waveguide layer; A part of the first signal electrode is located in the electrode layer, a part is located in the bridge layer, and the part of the first signal electrode located in the bridge layer is electrically connected with the part of the first signal electrode located in the electrode layer, in a direction perpendicular to the substrate , the part of the first signal electrode located on the bridge layer overlaps with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, A part of the first ground electrode is located in the electrode layer, a part is located in the bridge layer, and the part of the first ground electrode located in the bridge layer is electrically connected with the part of the first ground electrode located in the electrode layer, in a direction perpendicular to the substrate , the part of the first ground electrode located on the bridge layer overlaps with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, A part of the second ground electrode is located in the electrode layer, a part is located in the bridge layer, and the part of the second ground electrode located in the bridge layer is electrically connected with the part of the second ground electrode located in the electrode layer, in a direction perpendicular to the substrate , the part of the second ground electrode located on the bridge layer overlaps with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, The first ground electrode is located on the electrode layer, and in a direction perpendicular to the substrate, the first ground electrode does not overlap with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, A part of the first ground electrode is located in the electrode layer, a part is located in the bridge layer, and the part of the first ground electrode located in the bridge layer is electrically connected with the part of the first ground electrode located in the electrode layer, in a direction perpendicular to the substrate , the part of the first ground electrode located on the bridge layer does not overlap with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, The second ground electrode is located on the electrode layer, and in a direction perpendicular to the substrate, the second ground electrode does not overlap with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, A part of the second ground electrode is located in the electrode layer, a part is located in the bridge layer, and the part of the second ground electrode located in the bridge layer is electrically connected with the part of the second ground electrode located in the electrode layer, in a direction perpendicular to the substrate , the part of the second ground electrode located on the bridge layer does not overlap with the first waveguide arm and the second waveguide arm. The folded Mach-Zehnder modulator according to claim 5, wherein, The waveguide layer is a ridge waveguide layer, including a slab layer and a ridge layer on the slab layer, the first waveguide arm and the second waveguide arm are located on the ridge layer, and the electrode layer is formed on the surface of the slab layer away from the substrate. The folded Mach-Zehnder modulator according to claim 5, wherein, The waveguide layer is a ridge waveguide layer, including a flat layer and a ridge layer on the flat layer, the first waveguide arm and the second waveguide arm are located on the ridge layer, the flat layer has grooves, and the electrode layer is embedded in the grooves. The folded Mach-Zehnder modulator according to claim 5, wherein, The waveguide layer is a ridge layer including the first waveguide arm and the second waveguide arm, and the electrode layer is formed on the surface of the isolation layer away from the substrate. The folded Mach-Zehnder modulator according to any one of claims 1 to 14, further comprising: The phase compensation modulation module is arranged between the radio frequency electrode and the light splitting element, or between the radio frequency electrode and the light combining element.

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