JPH09138326A - Photosemiconductor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the photosemiconductor module which makes it easy to position a photosemiconductor chip and an optical fiber and has high coupling efficiency by joining and fixing a heat sink where the photosemiconductor chip is fixed and a fiber block where the optical fiber is fixed. SOLUTION: The photosemiconductor module 1 is equipped with a semiconductor optical amplifier chip 2 and fiber blocks 3 and 4 which are arranged on the light incidence and projection sides of the optical amplifier chip 2, and they are adhered and fixed with an adhesive 5. The optical amplifier chip 2 is fixed onto the heat sink 6. The optics amplifier chip 2 is provided with conversion parts 2a and 2b which enlarges a mode field nearby the incidence-side and projection-side end surfaces. The fiber blocks 3 and 4 have ribbon fibers 3b and 4b adhered and fixed in fiber holes 3a and 4a and, the end surfaces 3a and 4c are polished together with the ribbon fibers 3b and 4b.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical semiconductor module.

[0002]

2. Description of the Related Art An optical semiconductor module in which a single mode optical fiber is coupled to a semiconductor optical device such as a semiconductor laser or a semiconductor optical amplifier has been realized. As such an optical semiconductor module, for example, there is an optical semiconductor module in which light emitted from an optical semiconductor chip is condensed by a set of lenses and coupled to an optical fiber, but it has a drawback that it is expensive because of the large number of constituent parts. there were.

Therefore, in order to solve the above drawbacks, in recent years, a mode field converter is provided in an optical semiconductor chip,
It has been proposed to eliminate the need for a lens by increasing the coupling efficiency with a single-mode fiber (IE
EE Photonics Technology Letters, Vol. 7, No. 5, Ma
y 1995, P. 476-478).

[0004]

In the conventional optical semiconductor module described above, a single mode fiber (optical fiber) having a relative refractive index difference of 0.3% is positioned by a V groove formed in a fiber fixing plate, and The optical semiconductor chip is fixed to the chip fixing plate. Then, the optical semiconductor chip and the optical fiber are aligned so that the amount of coupling of the light emitted from the optical semiconductor chip to the optical fiber is maximized, and the fiber fixing plate and the chip fixing plate are positioned at the position where the coupling amount is maximum. And can be fixed and assembled.

However, in the conventional optical semiconductor module, the alignment in which the coupling amount between the optical semiconductor chip and the optical fiber is maximized, in particular, in order to determine the optimum position in the optical axis direction, the There is a problem in that it is necessary to perform a delicate position adjustment, and the manufacturing process is troublesome, resulting in an increase in cost. The present invention has been made in view of the above points,
It is an object of the present invention to provide an optical semiconductor module having high coupling efficiency, which facilitates alignment between an optical semiconductor chip and an optical fiber in the optical axis direction and can be manufactured at low cost.

[0006]

According to an optical semiconductor module of the present invention for achieving the above object, an optical semiconductor chip fixed on a heat sink and an optical fiber are fixed, and light from the optical semiconductor chip is incident. The fiber block is disposed on at least one of the side and the output side, and the heat sink and the fiber block are joined and fixed.

It should be noted that an organic adhesive is usually used for joining and fixing the heat sink and the fiber block from the viewpoint of translucency and joining conditions, but the translucency is not adversely affected.
As long as the reliability of the element is not deteriorated at the time of joining, joining by soldering or joining and fixing by fusion may be used. Preferably, in the optical fiber, the relative refractive index difference between the core and the clad is set to be larger than 0.3% and smaller than 3.5%. Here, the relative refractive index difference is a value obtained by dividing the refractive index difference between the core and the clad by the refractive index of the core.

Further, preferably, the heat sink and the optical semiconductor chip and the fiber block have a refractive index of 1
Bond with the above adhesive. More preferably, a mode field converter is provided near at least one of the light input / output end faces of the optical semiconductor chip. In the optical semiconductor module, the optical semiconductor chip is arranged and fixed such that the emission end face thereof is substantially flush with the heat sink end face or the emission end face is located inside the heat sink end face by about 0 to 5 μm. Further, in the case of coupling with an optical fiber at both input and output end faces of an optical amplification chip or the like, the end faces of both members can be made the same end face by setting the optical semiconductor chip and the heat sink to have substantially the same length. . On the other hand, in the fiber block, after the optical fiber is bonded and fixed, the end face is polished, so that the end face of the fiber block and the end face of the optical fiber become the same face.

Therefore, in the optical semiconductor module of the present invention, the optical semiconductor chip and the optical fiber can be formed simply by disposing the fiber block on at least one of the light incident side and the light emitting side of the optical semiconductor chip fixed on the heat sink. The gap between them in the optical axis direction becomes very small, and the alignment in the optical axis direction becomes extremely easy.

At this time, according to the second aspect of the invention, since the relative refractive index difference between the core and the clad is larger than that of a normal single mode fiber, the coupling efficiency between the optical semiconductor chip and the optical fiber is increased. And the alignment of the both in the optical axis direction becomes easy. Further, according to the invention of claim 3, the influence of reflection at the interface with the optical fiber can be ignored, the spread of the light emitted from the optical semiconductor chip becomes smaller than that in the case of air, and the coupling loss becomes further smaller.
As the adhesive that can be applied to the invention of claim 3, an epoxy-based or acrylic-based adhesive whose refractive index is matched with that of the optical fiber can be used, and for example, acrylate # 4190.
W and the like are preferable.

Further, according to the invention of claim 4, the light density in the vicinity of the end face of the semiconductor chip is reduced, and heat generation at the end face is suppressed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to FIGS. Embodiment 1 FIGS. 1 and 2 explain a first embodiment of the present invention. An optical semiconductor module 1 includes a semiconductor optical amplifier chip (hereinafter referred to as “optical amplifier chip”) 2 and an optical amplifier chip. 2 and the fiber blocks 3 and 4 arranged on the light input / output sides of the light, and are fixedly adhered by an adhesive 5.

The optical amplifier chip 2 is fixed on the heat sink 6 and is set to have a length slightly shorter than that of the heat sink 6 in order to avoid collision with the fiber blocks 3 and 4. As shown in FIG. 1, the optical amplifier chip 2 has an optical axis tilted by about 7 degrees with respect to the end face in order to suppress end face reflection, and a conversion unit for expanding a mode field near the end face on the input / output side. 2a and 2b are provided. Therefore, in the optical amplifier chip 2, the active layer is not exposed on both end faces.

Here, since the fiber blocks 3 and 4 have the same structure, only the fiber block 3 will be described, and the fiber block 4 will be denoted by the corresponding reference numerals in the figure and will not be described. The fiber block 3 is formed by adhering and fixing the ribbon fiber 3b to the fiber hole 3a and polishing the end face 3c together with the ribbon fiber 3b. Here, the fiber hole 3a considers the inclination of the optical axis of the optical amplifier chip 2 in order to suppress the end facet reflection of the optical fiber forming the ribbon fiber 3b, and considers the direction of abutting with the optical amplifier chip 2 in the horizontal plane. And is formed with an inclination of about 17 degrees. The optical fiber forming the ribbon fiber 3b has the same relative refractive index difference between the core and the clad as a normal single mode fiber.
It is 0.3%.

Therefore, in the optical semiconductor module 1, for example, the light transmitted through the ribbon fiber 3b of the fiber block 3 is optically amplified when passing through the optical amplifier chip 2 and emitted to the ribbon fiber 4b of the fiber block 4. To be done. At this time, the optical semiconductor module 1 is provided with the conversion units 2a and 2b near both end surfaces of the optical amplifier chip 2. Therefore, in the optical amplifier chip 2, since the mode field is expanded near the end face and the light density is reduced, heat generation at the end face is suppressed. Therefore, in the optical semiconductor module 1, even if the adhesive 6 is attached to the end surface of the optical amplifier chip 2, there is no problem and the reliability is not deteriorated.

When the optical semiconductor module 1 configured as described above is manufactured, it takes about 10 minutes for each end face to align and bond the fiber blocks 3 and 4 to each end face of the optical amplifier chip 2. As a result, a very good module 1 having a coupling loss of about 3.5 dB per end face and a gain of 20 dB or more could be obtained without complicated steps.

On the other hand, when an optical amplifier chip having the same structure is used as the optical semiconductor chip to manufacture the optical semiconductor module described in the prior art, in order to align the optical semiconductor chip and the single mode fiber at the optimum position,
About 1 hour was required for each end face. However, the coupling loss was about 3.5 dB for each end face. Second Embodiment Next, a second embodiment of the present invention will be described. The optical semiconductor module of the second embodiment uses the optical semiconductor module 1 of the first embodiment except that a ribbon fiber having a relative refractive index difference of 2.3% between the core and the clad of the optical fiber is used. 3, the components other than the ribbon fiber are denoted by the same reference numerals, and the ribbon fibers of the present embodiment have the reference numerals 3d and 4d, respectively.
Make the explanation simple.

The optical semiconductor module 1 includes a heat sink 6
The fiber blocks 3 and 4 are bonded and fixed by an adhesive 5 to the optical amplifier chip 2 fixed above. The fiber blocks 3 and 4 are obtained by adhering and fixing the ribbon fibers 3d and 4d to the fiber holes 3a and 4a, respectively, and polishing the end faces 3c and 4c together with the ribbon fibers 3d and 4d. Here, an optical amplifier chip having the same structure is used as an optical semiconductor chip, and an optical fiber having a relative refractive index difference of 2.3% is used in place of the single mode fiber having a relative refractive index difference of 0.3% described in the prior art. Was used to manufacture an optical semiconductor module. As a result, it took about one and a half hours for each end face to align the optical semiconductor chip and the single mode fiber at the optimum positions.

On the other hand, in the optical semiconductor module 1 of this embodiment, it takes about 10 minutes for each end face to align and bond the fiber blocks 3 and 4 to each end face of the optical amplifier chip 2. , The coupling loss was about 2.5 dB per end face, which was further improved. Here, in principle, the larger the relative refractive index difference, the better the coupling efficiency of the optical fiber. Therefore, the relative refractive index difference is 1.4%, 2.3% and 3.
The optical semiconductor module 1 was assembled using 1% optical fiber, and the coupling loss per end face was measured and found to be 1.8 dB, 2.5 dB and 2.6 dB, respectively.

The optical semiconductor module of the present invention has the following structure.
Since there is a slight gap between the end face of the optical fiber and the optical semiconductor chip, if the relative refractive index difference becomes too large, the advantage of using the optical fiber having a large relative refractive index difference cannot be utilized. Therefore, in the present invention, the relative refractive index difference is set to be larger than the relative refractive index difference (= 0.3%) of a normal single mode fiber and smaller than 3.5%. Third Embodiment Further, the optical semiconductor module may have a configuration in which the fiber block 12 is adhered and fixed to the light emitting side of the semiconductor laser chip 11 with the adhesive 13 as in the optical semiconductor module 10 shown in FIG. With this configuration, the other end surface of the optical semiconductor module 10 is opened, and the emission intensity of the semiconductor laser chip 11 can be monitored.

Here, the semiconductor laser chip 11 is fixed on the heat sink 14, and is set to have a length slightly shorter than that of the heat sink 14 in order to avoid collision with the fiber block 12. The semiconductor laser chip 11 is shown in FIG.
As shown in FIG. 5, the converter 11 has an optical axis perpendicular to the end face and expands the mode field near the end face on the light emission side.
a is provided.

In the fiber block 12, the ribbon fiber 12b is bonded and fixed to the fiber hole 12a, and the end face 1 is formed.
2c is polished together with the ribbon fiber 12b. Here, the fiber hole 12a is formed in a horizontal plane in parallel with the direction of butting to the semiconductor laser chip 11. In the optical fiber forming the ribbon fiber 12b, the relative refractive index difference between the core and the clad is 0.3%, which is the same as that of a normal single mode fiber.

[0023]

As is apparent from the above description, according to the present invention, it is easy to align the optical semiconductor chip and the optical fiber in the optical axis direction, and the high coupling which can be manufactured at low cost is provided. An optical semiconductor module having efficiency can be provided. At this time, according to the invention of claim 2,
Since the relative refractive index difference between the core and the clad is larger than that of a normal single-mode fiber, the coupling efficiency between the optical semiconductor chip and the optical fiber is improved, and the alignment of the both in the optical axis direction is facilitated. It can be carried out.

According to the invention of claim 3, the influence of reflection at the interface with the optical fiber can be ignored, and the spread of the light emitted from the optical semiconductor chip becomes smaller than that in the case of air, so that the coupling loss is reduced. It can be made smaller.
Further, according to the invention of claim 4, since the light density in the vicinity of the end face of the semiconductor chip is reduced, heat generation at the end face can be suppressed, and the reliability of the optical semiconductor module is improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of an optical semiconductor module of the present invention.

FIG. 2 is a side view of the optical semiconductor module of FIG.

FIG. 3 is a plan view showing a second embodiment of the optical semiconductor module of the present invention.

FIG. 4 is a plan view showing a third embodiment of the optical semiconductor module of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical semiconductor module 2 Optical amplifier chip 2a, 2b Conversion part (mode field) 3,4 Fiber block 3a, 4a Fiber hole 3b, 4b Ribbon fiber 3c, 4c End surface 3d, 4d Ribbon fiber 5 Adhesive 6 Heat sink 10 Optical semiconductor Module 11 Semiconductor laser chip 11a Converter (for mode field) 12 Fiber block 12a Fiber hole 12b Ribbon fiber 12c End face 13 Adhesive 14 Heat sink

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Muno 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (4)

[Claims] 1. An optical semiconductor chip fixed on a heat sink, and a fiber block on which an optical fiber is fixed and arranged on at least one of a light incident side and a light emitting side of the optical semiconductor chip. An optical semiconductor module, in which a fiber block is bonded and fixed. 2. The optical semiconductor module according to claim 1, wherein the optical fiber has a relative refractive index difference between the core and the clad of more than 0.3% and less than 3.5%. 3. The optical semiconductor module according to claim 1, wherein the heat sink and the optical semiconductor chip are bonded to the fiber block with an adhesive having a refractive index of 1 or more. 4. The optical semiconductor module according to claim 1, wherein a mode field converter is provided near at least one of the light input / output end faces of the optical semiconductor chip.