JPH0484475A - Hermetically sealed package structure of semiconductor laser pump mojule - Google Patents

Abstract

PURPOSE:To remove a monitor photodiode module to miniaturize a panel and achieve a low cost by forming an hermetically sealed package into the shape of a box, providing a window glass through which semiconductor laser beam is transmitted on one of the facing side surfaces thereof, and providing a window glass which shuts off the semiconductor laser beam. CONSTITUTION:A window glass 13 through which a semiconductor laser beam for pumping-light source is transmitted is disposed on a side surface 12a of the facing side surfaces 12a, 12b of a box-shaped package 12 made of a metallic material having a low thermal expansion coefficient. A window glass 14 which shuts of the semiconductor laser beam for bumping and permits signal light to pass therethrough is disposed on the other side surface 12b. Although the window glasses 13 and 14 are mounted on a pipe 15, they may be mounted directly on the facing side surfaces 12a, 12b of the box-shaped package 12. To perform a function as an airtight package, a relay terminal 16 for electrically connecting the interior and exterior of the package is incorporated hermetically by glass soldering or the like in the side surfaces 12c, 12d other than the facing side surfaces of the box-shaped package 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pumping light source for an optical fiber amplifier doped with erbium (Er3+), which is a rare earth metal, and particularly to a pumping light source using a high-output semiconductor laser as the pumping light source. This invention relates to an airtight package structure for a semiconductor laser pump module.

[Conventional technology]

Optical fiber amplifiers are attracting attention as optical amplifiers that can directly amplify optical signals without using electrical circuits. As this optical fiber amplifier, there is an optical fiber amplifier doped with erbium (Er''), but pumping light is required to amplify the signal light.

Conventionally, dye lasers and solid-state lasers have been used as excitation light sources, but the application of small semiconductor lasers was a prerequisite for commercialization as optical communication systems.

On the other hand, requirements for semiconductor lasers include a specific wavelength, high output, and high reliability, and a laser with a wavelength of approximately 1490 nm is considered as a semiconductor laser that satisfies these requirements.

An example of the configuration of a conventional optical fiber amplifier is shown in FIG.

In the figure, a wavelength combining coupler 2 is provided at the input end of an erbium-doped optical fiber 1, and the signal light from a signal semiconductor laser module 3 and the pumping light from a pumping semiconductor laser module 4 are combined into an erbium-doped optical fiber 1. This shows that the incident and amplified signal light is sent out to the trunk cable 5.

On the other hand, in order to stably output this amplified light, it is necessary to control the pumping light of the pumping semiconductor laser module 4. As an example of this control means, a short wavelength filter 6 that blocks excitation light from the excitation semiconductor laser module 4, for example, wavelengths below 1490 nm, and a coupler having a branching ratio of about 1:10 are provided at the output end of the erbium-doped optical fiber 1. 7 is provided to slightly reflect only the signal light of, for example, 1530 nm, and this reflected light is taken into the monitoring photodiode module 8. Accordingly, a method has been proposed in which the APC circuit 11 consisting of the differential amplifier 9, the LD current control circuit 10, etc. is operated from the output photocurrent, and the excitation semiconductor laser module 4 is driven and controlled.

[Problem to be solved by the invention]

On the other hand, in response to the current demand for downsizing and cost reduction of optical communication devices, the excitation light source and monitoring receiver are separated as shown in this configuration example, so the excitation semiconductor laser One module 4 and one monitor photodiode module 8 were required. That is, since the size of this monitor photodiode module 8 is usually about the same size as the excitation semiconductor laser module 4, it is substantially the same as the excitation semiconductor laser module 4.
It was necessary to secure a mounting area for two units on the panel, which was an obstacle to downsizing. Further, since the monitor photodiode module 8 itself requires approximately the same number of parts and the number of manufacturing steps as the excitation semiconductor laser module 4, the corresponding increase in cost has also been an obstacle to cost reduction.

Therefore, it is an object of the present invention to solve the above-mentioned drawbacks by integrating a pumping light source, which is essential to the configuration of an optical fiber amplifier, and a monitor for driving and controlling the pumping light source.

[Means to solve the problem]

In order to achieve the above object, the airtight 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 as a pumping light source of an erbium-doped optical fiber amplifier. A window glass that transmits the semiconductor laser light is provided on one of the opposing side surfaces of the box shape, and a window glass that blocks the semiconductor laser light is provided on the other opposing side surface.

[Effect]

As described above, according to the present invention, the conventional monitor photodiode module can be removed and integrated into one semiconductor laser pump module, making it possible to downsize the panel and reduce costs.

〔Example〕

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

FIG. 1 is a cross-sectional view showing an embodiment of an airtight package structure for a semiconductor laser pump module according to the present invention, and FIG. 2 is a perspective view of the same airtight package structure. In this embodiment, one side 12a of the opposing sides 12a and 12b of the box-shaped package 12 made of a metal material with a small coefficient of thermal expansion is used.
A window glass 13 that transmits the semiconductor laser light for the excitation light source
In addition, a window glass 14 is provided on the other side surface 12b to block excitation semiconductor laser light and to transmit signal light. Note that in this embodiment, the window glass 1
3 and 14 are attached to the vibrator 15, but they may be attached directly to the opposing sides 12a, 12b of the box-shaped package 12.

Further, in order to function as an airtight package, a relay terminal 16 for electrically connecting the inside and outside of the package is hermetically assembled with glass solder or the like on the side surface 12C112d of the box-shaped package 12 other than the opposing side surface. Furthermore, the above 2
3 (A), (B), and (C) are enlarged views for explaining the window glass 14 that blocks the excitation semiconductor laser light and transmits the signal light among the window glasses 13 and 14. show. The window glass 14 is made by processing an optical glass 14a such as BK7 or sapphire glass into a disk shape, and providing an anti-reflection film 14b by depositing a dielectric material such as 8102 on one side surface, and applying a similar dielectric material on the other side surface. The short wavelength blocking film 14C is provided by vapor-depositing a material. The wavelength characteristics after the short wavelength blocking film 14C and the antireflection film 14b are deposited are shown in FIG. 3(C).
As shown in the figure, the short wavelength range including 1490 nm, which is the wavelength of the excitation light source, is greatly attenuated, and the long wavelength range, which is 1530 nm or more, which is the wavelength of the signal light, is transmitted as much as possible. To obtain this characteristic, calculations are made taking into consideration the material characteristics of the optical glass 14a and the characteristics of the dielectric material, and the deposition conditions are set. Usually, several types of dielectric materials are combined and deposited in many layers. be done.

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

The fourth enlarged view is a partial enlarged view for explaining the state in which the window glass 14 made in this way is assembled into an airtight package.
As shown in the figure. As shown in the figure, a window glass 14 in which an anti-reflection film 14b, a short wavelength blocking film 14C, and a metal film 14 (l) are deposited on an optical glass 14a is attached to a vibrator which is airtightly attached to an airtight package 12 by silver brazing or the like. It is airtightly attached to the window glass mounting seat 17 of No. 15 with a solder material 18 such as gold/tin solder. By adopting such a structure, the inside and outside of the airtight package 12 are completely sealed. becomes.

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 14b and metal film 14d are similarly deposited. It is incorporated using the mounting method shown. However, in this example, it is attached using gold/tin solder, but glass solder such as low melting point glass may also be used, and in this case, the metal film 14d becomes unnecessary.

By adopting the package structure of the present invention as described above, it becomes possible to mount a combination element that integrates a semiconductor laser element and a monitoring photodiode element, which is an object of the present invention. An example of this implementation is shown in FIG.

That is, this is possible by manufacturing an integrated element in which the semiconductor laser element 20 and the monitor photodiode element 21 are attached to the integrated substrate 19 in opposite directions; conversely, the design of such an integrated element is A possible semiconductor laser pump module 22 can be realized. In other words,
The excitation light from the semiconductor laser element 20 is transmitted through the window glass 13 and input into the optical fiber 23, and the branched 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 and irradiated onto the monitor photodiode element 21.

Therefore, whereas conventionally one semiconductor laser module for excitation and one photodiode module for monitoring were required, by using the airtight package of the present invention, it is possible to realize a semiconductor laser pump module that is integrated into one module. can. In particular, it can be realized with a size comparable to that of conventional excitation semiconductor laser modules.

Further, an application example of a semiconductor laser amplifier module realized using the airtight package of the present invention is shown in FIGS. 6 and 7. It is only necessary to guide the branched light from the coupler 26 or the fusion coupler 27 at the output end of the erbium-doped optical fiber 25 to the monitor photodiode element 30a of the semiconductor laser pump module 30 through the monitor optical fibers 28 and 29, which is a conventional configuration example. You can remove the monitor photodiode module used in the . Note that the monitoring optical fibers 28 and 29 are normal single mode fibers or multimode fibers. Also, Figure 6,
In FIG. 7, reference numeral 30b denotes a semiconductor laser element, 31
Reference numeral 32 indicates a signal semiconductor laser module, 32 a wavelength combining coupler, and 33 a trunk optical cable.

In the above-described embodiments, the package structure is box-shaped and made of metal, but the present invention is also applicable to cases where the package structure is a modified box shape or a combination of materials such as ceramics.

〔Effect of the invention〕

As described above, by adopting the airtight package structure of the present invention, the conventional monitor photodiode module can be removed and integrated into one semiconductor laser pump module, contributing to panel miniaturization and cost reduction. It has this excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the airtight package structure of the semiconductor laser pump Modineal according to the present invention, FIG. 2 is a perspective view of the same airtight package structure, and FIGS. 3 (A) to (C) are cross sections of window glass. Figure 4 is a partially enlarged view for explaining the method of installing the window glass, Figure 5 is a semiconductor laser pump assembled using the airtight package of the present invention. A sectional view of the module, FIGS. 6 and 7 are block diagrams of an optical fiber amplifier showing an application example of this semiconductor laser pump module, and FIG. 8 is a block diagram of a conventional optical fiber amplifier. 12... Box-shaped package, 12a, 12b... Opposite side, 13.14...
... Window glass, 14a ... Optical glass, 14b ... Antireflection film, 14C ... Short wavelength blocking film, 14d ... Metal film, 25... Erbium Dorff optical fiber, 30.
... Semiconductor laser pump Modinir. Applicant: NEC Corporation Agent
Patent Attorney Umeo Yamauchi Figure 1 Figure 3 (A) Figure 3 CB) 14a Figure 3 (C) Figure 2 1550 (7LTL) Naoki Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. In an airtight package structure of a semiconductor laser pump module used as a pumping light source for an erbium-doped optical fiber amplifier, the airtight package has a box shape, and the semiconductor is attached to one of the opposite sides of the box shape. 1. An airtight package structure for a semiconductor laser pump module, characterized in that a window glass that transmits laser light is provided, and a window glass that blocks the semiconductor laser light is provided on the other opposing side surface. 2. The window glass that blocks the semiconductor laser light is made by depositing a dielectric multilayer film on an optical glass plate to block short wavelengths that include the wavelength of the semiconductor laser light, and blocks long wavelengths that do not include the wavelength of the semiconductor laser light. 2. The airtight package structure for a semiconductor laser pump module according to claim 1, wherein the airtight package structure is configured to transmit the light.