JP2586190B2 - Airtight package structure of semiconductor laser pump module - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump light source for an optical fiber amplifier doped with erbium (Er ³⁺ ), which is a rare earth metal, and more particularly, to a high power semiconductor laser as the pump light source. The present invention relates to an airtight package structure of a used semiconductor laser pump module.

[Conventional technology]

Optical fiber amplifiers have attracted attention as optical amplifiers that can directly amplify optical signals without relying on electric circuits. As this optical fiber amplifier, there is an optical fiber amplifier doped with erbium (Er ³⁺ ), but pump light is required to amplify the signal light. Conventionally, a dye laser or a solid-state laser has been used as the excitation light source. However, in order to be commercialized as an optical communication system, the application of a small semiconductor laser has been required.

On the other hand, a specific wavelength, high output, and high reliability are required for the requirements for the semiconductor laser, and a laser having a wavelength of about 1490 nm has been considered as a semiconductor laser satisfying these conditions.

FIG. 8 shows a configuration example of a conventional optical fiber amplifier. In the figure, a wavelength combining coupler 2 is provided at an incident end of an erbium-doped optical fiber 1, a signal light from a signal semiconductor laser module 3 and a pump light from a pumping semiconductor laser module 4 are combined, and the combined light enters the erbium-doped optical fiber 1. , The amplified signal light is transmitted to the trunk cable 5.

On the other hand, in order to output this amplified light stably, it is necessary to control the pumping light of the pumping semiconductor laser module 4. As an example of this control means, the semiconductor laser module 4 for excitation is provided at the emission end of the erbium-doped optical fiber 1.
For example, a short wavelength filter 6 for blocking the wavelength of 1490 nm or less and a coupler 7 having a branching ratio of about 1:10 are provided. For example, only a signal of 1530 nm is slightly reflected and the reflected light is used as a monitoring photodiode. The module 8 is loaded. Thus, means for operating the APC circuit 11 including the differential amplifier 9 and the LD current control circuit 10 from the output photocurrent to drive and control the excitation semiconductor laser module 4 has been proposed.

[Problems to be solved by the invention]

However, on the other hand, in contrast to the current demand for downsizing and cost reduction of optical communication devices, the excitation light source and the monitoring light receiver are separated as shown in this configuration example. One module 4 and one monitoring photodiode module 8 were required. That is, since the size of the monitoring photodiode module 8 is generally the same as the size of the pumping semiconductor laser module 4, a mounting area for substantially two pumping semiconductor laser modules 4 is secured on the panel. Need to
This was an obstacle to miniaturization. Further, since the number of components and the number of man-hours required for the monitor photodiode module 8 itself are almost the same as those of the pumping semiconductor laser module 4, the increase in cost is an obstacle to cost reduction.

Accordingly, an object of the present invention is to solve the above-mentioned drawbacks by integrating an excitation light source indispensable for the configuration of an optical fiber amplifier and a monitor for controlling the driving thereof.

[Means for solving the problem]

In order to achieve the above object, the hermetic package structure of a semiconductor laser pump module according to the present invention is a hermetic package structure of a semiconductor laser pump module used for an excitation light source of an erbium-doped optical fiber amplifier. A window glass for transmitting the semiconductor laser light is provided on one of the box-shaped opposed side surfaces, and a window glass for blocking the semiconductor laser light is provided on the other of the opposed side surfaces.

[Action]

As described above, according to the present invention, the conventional monitoring photodiode module can be eliminated and integrated into a single semiconductor laser pump module.
Cost reduction can be achieved.

〔Example〕

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

FIG. 1 is a cross-sectional view showing one embodiment of an airtight package structure of a semiconductor laser pump module according to the present invention.
The figure is a perspective view of the airtight package structure. In the present embodiment, a window glass 13 that transmits the semiconductor laser light for the excitation light source is provided on one of the side surfaces 12a of the opposing side surfaces 12a and 12b of the box-shaped package 12 made of a metal material having a small coefficient of thermal expansion, and Block the semiconductor laser light for excitation on the other side surface 12b,
In this configuration, a window glass 14 capable of transmitting signal light is provided. In this embodiment, the window glasses 13 and 14 have a structure in which they are attached to the pipe 15.
May be directly attached to the opposed side surfaces 12a and 12b.

Further, in order to fulfill the function as an airtight package, relay terminals 16 for electrically connecting the inside and outside of the package are hermetically incorporated into the side surfaces 12c and 12d other than the opposing side surfaces of the box-shaped package 12 with glass solder or the like. Further, among the two window glasses 13 and 14, an enlarged view for explaining the window glass 14 that blocks the semiconductor laser light for excitation and transmits the signal light is shown in FIG.
Figures (A), (B) and (C) show. Window glass 14, BK7
Optical glass 14a such as glass or sapphire glass is processed into a disk shape, and a dielectric such as Sio2 is deposited on one side surface to prevent reflection.
14b, and a similar dielectric material is deposited on the other side surface to provide a short-wavelength blocking film 14c. The wavelength characteristics after the deposition of the short wavelength blocking film 14c and the antireflection film 14b are the wavelengths of the excitation light source as shown in FIG. 3 (C).
It is designed to greatly attenuate the short wavelength region including 1490 nm and transmit the long wavelength region of 1530 nm or more, which is the wavelength of signal light, as much as possible. In order to obtain this characteristic, calculation is performed in consideration of the material characteristics of the optical glass 14a and the characteristics of the dielectric material, and the vapor deposition conditions are set.In general, several types of dielectric materials are combined and vapor deposition is performed in multiple layers. Is done.

In addition, a metal film 14d is deposited around one surface of the optical glass 14a (the surface of the antireflection film 14b in this example) so as to be attached to a package.

FIG. 4 is a partially enlarged view for explaining a state in which the window glass 14 thus manufactured is incorporated in an airtight package.
Shown in the figure. As shown in the figure, a window glass 14 in which an antireflection film 14b, a short wavelength blocking film 14c, and a metal film 14d are deposited on an optical glass 14a is a It is airtightly attached to a window glass mounting seat 17 with a solder material 18 such as gold or tin solder. By employing such a structure, the inside and the outside of the hermetic package 12 are completely sealed.

On the other hand, the window glass 13 shown in FIG. 1 is obtained by removing only the short-wavelength blocking film 14c deposited on the window glass 14, and the antireflection film 14d and the metal film 14d are similarly deposited. It is incorporated with the mounting method shown. However, in this example, the bonding is performed using gold / tin solder, but glass solder such as low-melting glass may be used. In this case, the metal film 14d is not required.

With the package structure of the present invention as described above, it is possible to mount a combined element in which the semiconductor laser element and the monitoring photodiode element, which are the objects of the present invention, are integrated. This embodiment is shown in FIG. That is, the integrated substrate
19 shows a semiconductor laser element 20 and a monitor photodiode element 21
Can be made by fabricating an integrated element in which the semiconductor laser pump modules 22 are mounted in opposite directions.
Can be realized. That is, the excitation light from the semiconductor laser element 20 is transmitted through the window glass 13 and made incident on the optical fiber 23, and the branch light from the erbium-doped optical fiber amplifier is guided through the optical fiber 24. Then, the excitation light component of the semiconductor laser element 20 is removed by the window glass 14, and only the signal light component is transmitted to irradiate the monitor photodiode element 21.

Therefore, conventionally, one semiconductor laser module for excitation and one photodiode module for monitoring were required, but by using the hermetic package of the present invention, a semiconductor laser pump module integrated into one module can be realized. In particular, the size can be realized by the same size as the conventional semiconductor laser module for excitation.

6 and 7 show an application example of a semiconductor laser amplifier module realized by using the hermetic package of the present invention. The branch light from the coupler 26 or the fusion coupler 27 at the emission end of the erbium-doped optical fiber 25 need only be guided to the monitor photodiode element 30a of the semiconductor laser pump module 30 by the monitor optical fibers 28 and 29, which is a conventional configuration example. The used monitoring photodiode module can be deleted. The monitor optical fiber 2
For 8, 29, normal single mode fiber or multimode fiber is used. 6 and 7, reference numeral 30b denotes a semiconductor laser element, 31 denotes a signal semiconductor laser module, 32 denotes a wavelength combining coupler, and 33 denotes a trunk optical cable.

In the above-described embodiment, the package structure is box-shaped and the material is metal, but the present invention is also applicable to a case where the package structure is combined with a deformed box-shaped shape or a material such as ceramic.

〔The invention's effect〕

As described above, by adopting the hermetic package structure of the present invention, the conventional photodiode module for monitoring can be eliminated and integrated into one semiconductor laser pump module, thereby contributing to downsizing of the panel and cost reduction. It has excellent effects.

[Brief description of the drawings]

1 is a cross-sectional view showing the hermetic package structure of the semiconductor laser pump module according to the present invention, FIG. 2 is a perspective view of the hermetic package structure, and FIGS. 3A to 3C are cross-sectional views of window glass. FIG. 4 is a partially enlarged view for explaining a method of attaching a window glass, and FIG. 5 is a cross-sectional view of a semiconductor laser pump module assembled using the hermetic package of the present invention. FIGS. 6 and 7 are diagrams showing the configuration of an optical fiber amplifier showing an application example of the semiconductor laser pump module, and FIG. 8 is a diagram showing the configuration of a conventional optical fiber amplifier. 12: Box-type package, 12a, 12b: Opposite side surface, 13, 14: Window glass, 14a: Optical glass, 14b: Anti-reflective coating, 14c: Short wavelength blocking film, 14d: Metal film, 25 ... Erbium-doped optical fiber, 30 ... Semiconductor laser pump module.

Claims (2)

(57) [Claims] In an airtight package structure of a semiconductor laser pump module used as an excitation light source of an Erbium-doped optical fiber amplifier, the airtight package has a box shape, and the semiconductor laser light is transmitted through one of the opposing side surfaces of the box shape. A hermetic package structure of a semiconductor laser pump module, wherein a window glass is provided, and a window glass for blocking the semiconductor laser light is provided on the other of the opposite side surfaces. 2. A window glass for intercepting the semiconductor laser light, wherein a short-wavelength including the wavelength of the semiconductor laser light is intercepted by depositing a dielectric multilayer film on an optical glass plate and includes a wavelength of the semiconductor laser light. 2. The hermetic package structure of a semiconductor laser pump module according to claim 1, wherein the semiconductor laser pump module is configured to transmit light having a long wavelength.