JP2002076497A - Optical semiconductor airtight sealing container and optical semiconductor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor airtight sealing container and optical semiconductor module of high reliability not destroying a polarized plane, easily manufactured at a low cost. SOLUTION: This optical semiconductor airtight sealing container is provided with a light transmission window jointed to the cylindrical part of a container side wall with a solder brazing filler metal whose light transmission plane is tilted 6 degrees or more from the vertical line of a container bottom plate. The window material is composed of a plate whose main component is a regular hexagonal sapphire for which a metallized part is formed on the periphery leaving a circular light transmission part at the center. This optical semiconductor module uses it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor hermetically sealed container provided with a light transmitting window for accommodating an optical semiconductor element therein, and an optical semiconductor module using the optical semiconductor hermetically sealed container.

[0002]

2. Description of the Related Art In optical communication, the hermeticity of an optical semiconductor module is regarded as important in order to ensure high reliability. This is because, in a high-temperature and high-humidity state, the electrode portion of the optical semiconductor element is deteriorated, and the moisture that has entered the inside of the container is dewed to deteriorate the optical characteristics, so that the life of the optical semiconductor element for 10 years or more cannot be compensated. It is.

On the other hand, in an optical semiconductor module, it is necessary to optically couple an optical semiconductor element inside a container and an external optical fiber. Therefore, in order to optically couple the optical semiconductor element inside the container and an external optical fiber while maintaining the airtightness of the container, a light-transmitting window structure is adopted for the optical semiconductor hermetically sealed container.

In Japanese Patent Application Laid-Open No. 6-151629, sapphire is used for a light transmission type window. Since sapphire has excellent light transmittance and high strength, it is often used for a housing (airtightly sealed container) for an optical semiconductor module. This sapphire is used after being drilled into a circle.

Japanese Patent Application Laid-Open No. H11-54642 proposes a window structure of an optical semiconductor module using a substantially hexagonal borosilicate glass for a window plate. Borosilicate glass is inexpensive and superior in light transmission to sapphire.
It is an isotropic material that does not produce birefringence. The polarization plane collapses due to elastic strain caused by stress such as heat. However, as described in JP-A-11-54642, by applying a uniform stress to glass, the amount of polarization extinction ratio is 4
It has been found that it becomes as large as about 0 dB and no problem occurs. In addition, since a low-cost dicing process can be used in the case of a regular hexagonal shape, an effect of reducing the cost of the window material is also obtained. However, borosilicate glass also has a drawback of low strength, and it is still necessary to pay attention to use under worse conditions.

[0006] The collapse of the polarization plane is generally represented by the polarization extinction ratio. In the cross Nicol experimental system, the light emitting side polarizer is rotated by 90 degrees, the maximum light intensity is Imax, the minimum light intensity is Imin, and the polarization extinction ratio is 1
Defined as 0 × log ₁₀ (Imax / Imin).

[0007]

In recent years, in optical communications, it has become important to reduce the cost of optical semiconductor modules. Therefore, it is necessary to improve the window material of the hermetically sealed container, which is the housing of the optical semiconductor module. However, as described in the above-mentioned Japanese Patent Application Laid-Open No. 6-151629, drilling is required to process sapphire crystals into a circular shape, and in this case, the window material is scratched, and the yield rate is reduced. I will. For this reason, the cost was high.

On the other hand, with the advancement of high-density wavelength multiplexing technology and high-speed technology, the following problems have occurred. Maintaining the plane of polarization of light and obtaining uniformity of wavelength.
Of these, in order to solve the latter, it is preferable to form an external resonator structure via a fiber outside a hermetically sealed container such as an optical fiber grating, but at this time, it is necessary to maintain the polarization plane of light. . When this is expressed by the polarization extinction ratio at the intensity level, Imax such as 35 dB is 3 times smaller than Imin.
Strict conditions exceeding 000 times are required. In Japanese Patent Application Laid-Open No. H11-54642, use in fields requiring ultra-reliability for submarine cables is still being avoided because of a limited track record.

The present invention has been made in view of such conventional circumstances,
An object of the present invention is to provide an optical semiconductor hermetically sealed container and an optical semiconductor module which are easy to manufacture, low in cost, have high reliability, and do not lose the polarization plane.

[0010]

In order to achieve the above object, according to the present invention, a cylindrical portion of a side wall of a container is joined with a solder brazing material, and a light transmitting surface is inclined at least 6 degrees from a perpendicular of a container bottom plate. An optical semiconductor hermetic sealing container having a light transmitting window, wherein the window material has a substantially light hexagonal sapphire as a main component and a metallized portion formed around a circular light transmitting portion at the center. And a hermetically sealed optical semiconductor container characterized in that the plate is a sapphire sintered body.

An optical semiconductor module according to the present invention is characterized in that the optical semiconductor module has an optical semiconductor element inside the optical semiconductor hermetically sealed container and an optical fiber outside.

The regular hexagon has the highest yield when dicing at low cost. Compared with the conventional drilling, the cutting edge of dicing is smaller than the cutting edge of the drill, so that the yield is also high in this respect. In the dicing process, an adhesive wafer sheet can be used, so that there is no rebound of chips, a high yield rate can be achieved, and a window material can be manufactured, so that cost reduction can be achieved.

In a uniaxial crystal such as sapphire, birefringence does not occur by making the optical axis coincide with the C axis. If the incident light is linearly polarized light, birefringence does not occur because the plane of polarization and the C axis are on the same plane. In order to secure a polarization extinction ratio of 35 dB, which is a sufficient condition required in the field of optical communication,
The plane of polarization and the C-axis plane must be aligned. A small polarization extinction ratio causes loss and noise. However, by making the window material a sintered body of sapphire, it becomes a fine crystalline aggregate or an amorphous state, becomes optically isotropic, and breaks the polarization plane when light is transmitted to the window material. It can be removed regardless of orientation. For this reason, an optical semiconductor hermetically sealed container can be easily manufactured without performing positioning, and cost reduction can be achieved.

By using the optical semiconductor hermetically sealed container, it is possible to manufacture an optical semiconductor module which is low in cost, has high reliability and does not lose its polarization plane.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hermetically sealed optical semiconductor container of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view showing an example of a light transmitting window of the optical semiconductor hermetically sealed container of the present invention, and FIG. 2 is a plan view showing a plate mainly composed of sapphire as a window material. A circular cylindrical portion 3 is combined with a perforation formed in the container side wall 2 of the hermetically sealed container 1 and brazed, followed by gold plating or the like to produce a container intermediate product. 5 is a bottom plate. Further, the window material 4 is joined to the cylindrical portion 3 to form a light transmitting window. In the present invention, as shown in FIG. 2, the window material 4 leaves a circular light transmitting portion at the center. A plate composed mainly of substantially regular hexagonal sapphire having a metallized portion formed therearound is joined. In addition, this plate is made of aggregates of fine crystals of sapphire,
Alternatively, by making the sintered body in an amorphous state, it becomes optically isotropic, and the collapse of the polarization plane when light passes therethrough can be made irrespective of the direction of the window material, and the cost can be reduced.

Using the above-mentioned optical semiconductor hermetically sealed container,
An optical semiconductor module can be manufactured by connecting an optical semiconductor element inside and an optical fiber outside.

Example 1 A hermetically sealed optical semiconductor container was produced by silver brazing using Kovar for the bottom plate, Kovar for the side wall material, and Kovar for the cylindrical pipe of the light transmission type window. The terminal portion was made of a structure in which a Kovar pin was sealed with low-melting glass, and nickel-plated and gold-plated. In order to fit the sapphire plate into the side wall, a pipe having an angle plane of 6 degrees or more with respect to the side wall should be silver brazed so that the angle plane of 6 degrees or more with respect to the polarization plane is within 5 degrees. Attached. In practice, a cylindrical hole was made in the side wall, a cylindrical pipe was fitted, and the carbon jig was used for positioning. An AR coat of MgF was applied to the window material. This may be a multilayer film of TiO and SiO. Here, when θ (the angle between the optical axis and the C axis) is the Brewster's angle, ψ (the angle between the C axis and the polarization plane of the light) is further reduced to 0 ° to prevent the AR coating. May be. Metallization on sapphire is Ti / Pt / Au from the sapphire side. Dicing was used for sapphire processing. At this time, the metallization strength was improved by not performing metallization on the dicing line.
The sapphire was sealed to the housing with AuSn brazing material. The use of this window material reduced the cost of the window material by half.

When a fine crystalline aggregate of sapphire or an amorphous crystalline material is used for the window material, the relationship between the birefringence and the angle is lost due to optical isotropy. The polarization extinction ratio was 35 dB or more.
This eliminates the need for advanced pipe alignment. For this reason, the yield rate can be improved by 10%, and the cost can be further reduced.

Embodiment 2 The optical semiconductor module having the window structure of Embodiment 1 is provided with a PAN.
By connecting a DA fiber, light could be transmitted while maintaining a high degree of linear polarization. In this case, a plurality of excitation lights required for the optical fiber amplifier are polarization-synthesized, so that the optical fiber amplifier can be used efficiently. Further, the structure of the isolator can be simplified, and the cost can be reduced.

Example 3 A modulator module made of LN, which is an anisotropic optical material, using the container of Example 1 used a Mach tender type element. Since the polarization extinction ratio of the window is small, birefringence generated inside the LN modulator can be suppressed, and an optical signal having a good S / N ratio can be obtained.

Example 4 When the window structure of Example 1 was used for a semiconductor laser, light loss in an isolator connected outside the window could be suppressed.

Embodiment 5 In the semiconductor optical amplifier, polarization dependence was a problem.
After the plate was converted into linearly polarized light, the module using the case having the window having the structure of Example 1 could improve the amplification characteristics. As a result, the insertion loss of the wavelength conversion element using the semiconductor amplifier and the optical-optical switching element capable of high-speed operation can be reduced, and a signal light with a good S / N ratio can be obtained.

Embodiment 6 By providing a reflecting mechanism for selectively reflecting a specific wavelength, for example, a fiber grating outside the container of Embodiment 1, it is possible to resonate with the optical element inside the housing. At this time, disturbance of the oscillation mode caused by the birefringence of the window can be suppressed, and an optical semiconductor module excellent in wavelength selectivity can be provided. In addition, the loss was reduced, and the light intensity increased.

[0025]

According to the present invention, it is possible to provide an optical semiconductor hermetically sealed container having an easy-to-manufacture, low-cost, high-reliability, and window structure in which the polarization plane does not collapse. When an optical semiconductor hermetically sealed container employing this window is used, an optical semiconductor module having high light intensity and excellent mode stability can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a light transmission window of an optical semiconductor hermetically sealed container of the present invention.

FIG. 2 is a plan view showing a plate mainly composed of sapphire as a window material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hermetically sealed container 2 Container side wall 3 Cylindrical part 4 Plate (window material) mainly composed of sapphire 5 Bottom plate

Claims (3)

[Claims] 1. An optical semiconductor hermetically sealed container having a light transmitting window which is joined to a cylindrical portion of a side wall of a container with a solder brazing material and whose light transmitting surface is inclined at least 6 degrees from a perpendicular to a container bottom plate, The hermetically sealed optical semiconductor container, wherein the window member is formed of a plate having sapphire as a main component and having a substantially hexagonal shape with a metallized portion formed around the window material while leaving a circular light transmitting portion in the center. 2. The hermetically sealed optical semiconductor container according to claim 1, wherein said plate is a sapphire sintered body. 3. An optical semiconductor hermetically sealed container having a light-transmitting window which is joined to a cylindrical portion of a side wall of a container with a solder brazing material and whose light-transmitting surface is inclined at least 6 degrees from a perpendicular to a bottom plate of the container. The material is composed of a plate mainly composed of substantially regular hexagonal sapphire having a metallized portion formed around it while leaving a circular light transmitting portion in the center, and having an optical semiconductor element inside and an optical fiber outside. Characteristic optical semiconductor module.