JP3052351B2 - Light-emitting / light-receiving integrated module for optical fiber fault locator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting / receiving module, and more particularly to an integrated light emitting / receiving module for an optical fiber fault locator.

[Prior Art] Conventionally, a light emitting / receiving element used in an optical fiber fault point locator (OTDR) includes a module of a high-power semiconductor laser 1 as shown in FIG. 3 (a) and a module of FIG. 3 (b). And the avalanche photodiode 6 module shown in FIG. FIG. 2 shows the configuration of the optical fiber fault point locator.

The basic operation of the optical fiber fault locator (OTDR) is as follows. The high-power semiconductor laser 1 is pulse-driven by a pulse driver 13, and the optical pulse signal is passed through the optical fiber 4 to the directional coupler 14. Measuring optical fiber 15
The reflected light from the fault point is passed again through the directional coupler 14 and returned to the avalanche photodiode 6 as a light receiver to search for the fault point of the optical fiber 15. In this type of device, how large the dynamic range of the measurement can be determined by the performance of the device. For this purpose, a high-output light pulse and a low-noise light receiver are required.

[Problems to be solved by the invention]

However, from the viewpoint of widening the dynamic range, which is a characteristic required as a fault point locator, the avalanche photodiode 6, which is a conventional light receiving module,
Without a Peltier cooler as a cooling device, it is difficult to achieve low dark current because it depends on the element characteristics, and as a result, the performance as OTDR must be limited. There was nothing.

In addition, the high-power semiconductor laser, its driver, the avalanche photodiode as the light receiving element, and its amplifier circuit chip are all individually configured, leading to an increase in the overall cost of the device.

An object of the present invention is to provide an integrated light-emitting / light-receiving module for an optical fiber fault locator that achieves high output, wide dynamic range, and the like.

[Means for solving the problem]

In order to achieve the object, in the light-emitting / light-receiving integrated module for an optical fiber fault point locator according to the present invention, at least a package, a high-power semiconductor laser,
An integrated light-emitting / light-receiving module for an optical fiber fault locator having an avalanche photodiode and a Peltier cooler, wherein the package is a high-power semiconductor laser, an avalanche photodiode, and a Peltier cooler integrated into one. High-power semiconductor lasers output optical signals for searching for fault points in optical fibers, avalanche photodiodes convert optical signals reflected from optical fiber fault points into currents, and Peltier coolers use high-power semiconductors. It cools the laser and the avalanche photodiode.

The package includes a laser driver chip and a receiving amplifier chip in addition to the elements, and the laser driver chip drives a high-power semiconductor laser based on an external control signal. Yes, the receiving amplifier chip amplifies the output current of the avalanche photodiode.

[Action]

By mounting a high-power semiconductor laser and an avalanche photodiode on one Peltier cooler, high light output and low dark current are realized. In addition, cost advantages can be achieved by using an integrated module.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

 FIG. 1 is a block diagram showing one embodiment of the present invention.

The device that is the subject of the present invention is an optical fiber point of failure locator (OTDR). As shown in FIG. 2, the basic operation of the optical fiber fault locator is that the high-power semiconductor laser 1 is pulse-driven by the pulse driver 13 and the optical pulse signal is passed through the optical fiber 4a to the directional coupler 14. After that, the reflected light from the failure point of the optical fiber 15 to be measured passes through the directional coupler 14 again, and is returned to the avalanche photodiode 6 as a light receiver by the optical fiber 4b to search for the failure point of the optical fiber 15. In this type of device, how large the dynamic range of the measurement can be determined by the performance of the device. For that purpose, a photodetector for high-output light pulses and low noise is required.

Therefore, as shown in FIG. 1, in the present invention, a laser driver chip 9 for driving the high-power semiconductor laser 1 based on an external control signal (signal for pulse lighting), and a laser driver chip 9 driven by the laser driver chip 9 A high-power semiconductor laser 1 mounted on a chip carrier 12, a rod lens 2a for efficiently inputting an optical signal emitted from the semiconductor laser to the optical fiber, and an optical fiber 4a reaching the directional coupler 14. An optical fiber 4b that transmits an optical signal from the directional coupler 14, an avalanche photodiode 6 that converts the optical signal into a current, a rod lens 2b that causes the optical signal from the optical fiber 4b to enter the avalanche photodiode 6, and an avalanche photodiode 6. Receive amplifier chip 7 for amplifying output current, high-power semiconductor laser 1 and avalanche photodiode A Peltier cooler 8 for cooling the diode 6, a thermistor 11 for temperature detection, and a Peltier cooler 8 built in the package 10 and having the high-power semiconductor laser 1 and the avalanche photodiode 6
It is mounted on the top. The optical fibers 4a and 4b are fixedly held by the optical fiber fixing portions 5a and 5b in the package 10. …
Is installed.

According to the present invention, the high-power semiconductor laser 1 and the avalanche photodiode 6 are cooled by the Peltier cooler 8 and their temperatures are kept at room temperature or below. In the semiconductor laser 1, a high output is obtained with a decrease in temperature, and the avalanche photodiode 6 can also reduce a dark current component associated with noise, thereby reducing the dynamic range of the optical fiber fault point locator itself. Expansion becomes possible. Further, the driver chip 9 for driving the semiconductor laser 1 and the receiving amplifier circuit chip 7 for the avalanche photodiode 6 are simultaneously incorporated in the module, so that it is easy to use and at the same time, the light emitting / receiving element is integrated.
There is a cost advantage as a device.

〔The invention's effect〕

As described above, the present invention cools the high-power semiconductor laser and the avalanche photodiode with a Peltier cooler, so that the optical output of the semiconductor laser can be increased,
In addition, the dark current, which is a noise component of the avalanche photodiode, can be reduced, and the device can have a wide dynamic range. In addition, since the light-emitting and light-receiving devices are integrated, there is no need to use them individually,
The key device portion of the apparatus can be constituted by one integrated module, and the cost of the entire apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an optical fiber fault point locator, FIG. 3 (a) is a diagram showing a conventional semiconductor laser module, and FIG. 3 (b) () Is a diagram showing a conventional avalanche photodiode module. DESCRIPTION OF SYMBOLS 1 ... High power semiconductor laser 2 ... Rod lens 3 ... Terminal 4a, 4b ... Optical fiber 5a, 5b ... Optical fiber fixing part 6 ... Avalanche photodiode 7 ... Light receiving amplifier chip 8 ... Peltier cooler 9 ... Laser driver chip 10: Package, 11: Thermistor 12: Chip carrier

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G01M 11/00-11/02 G02B 6/42 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (2)

(57) [Claims] An integrated light-emitting / light-receiving module for an optical fiber fault locator having at least a package, a high-power semiconductor laser, an avalanche photodiode, and a Peltier cooler, wherein the package comprises a high-power semiconductor laser and an avalanche photodiode. And a Peltier cooler. The high-power semiconductor laser outputs an optical signal for searching for a fault point of the optical fiber, and the avalanche photodiode outputs a reflected light signal from the fault point of the optical fiber. An integrated light emitting / receiving module for an optical fiber fault locator, wherein the Peltier cooler cools a high-power semiconductor laser and an avalanche photodiode. 2. The package according to claim 1, wherein:
A laser driver chip and a receiving amplifier chip, wherein the laser driver chip drives a high-power semiconductor laser based on an external control signal, and the receiving amplifier chip outputs an output current of the avalanche photodiode. An integrated light-emitting / light-receiving module for an optical fiber fault point locator characterized by being amplified.