JPH11212041A - Semiconductor optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor optical element, which can be operated at high speed and applied to an optical communication system, at low cost by setting the full length of the element along with the propagating direction of an optical waveguide longer than a specified value and setting a distance between end faces, where the optical waveguide is formed, shorter than a specified value. SOLUTION: A light modulator 20 has a block-shaped semiconductor base part 21 and an integrally formed light propagating part 22. Then, a dimension 23 of the semiconductor base part 21 in lengthwise direction is set longer than 250 μm such as set to 250 μm, for example. Besides, a pair of end faces 24 are formed at the light propagating part 22, and a length dimension 25 of this light propagating part 22, namely, the distance between the end faces 24 is set shorter than 200 μm such as set to 200 μm, for example. Since the dimension 25 contributed to the conversion of digital signals to optical signals in the optical communication system is set shorter than 200 μm, the parasitic resistance of the light modulator 20 can be reduced and high-speed operation is enabled. Further, since the lengthwise dimension 23 of the light modulator 20 can be set longer than 250 μm, handling is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor optical device such as an optical modulator and a semiconductor laser used for optical communication.

[0002]

2. Description of the Related Art In a so-called trunk and subscriber optical communication system, a semiconductor optical device for converting a digital signal into an optical signal is required. This semiconductor optical device converts various digital signals into light intensity. As such an electro-optical conversion method, a method using an electro-absorption type optical modulator as an electro-optical conversion element,
There are two widely known methods, namely, a method of directly converting an injection current into a semiconductor laser to perform electro-optical conversion.

FIG. 11 is a perspective view showing a conventional optical modulator S1 used for electrical-optical conversion. This optical modulator S1
The structure of the optical modulator S1 will be briefly described below.
An n-InP buffer layer 2 and n-InGa
AsP-SCH layer 3, InGaAs and InGaAs
MQW light absorbing layer 4, p-InGa in which P is alternately stacked
An AsP-SCH layer 5 and a p-InP first cladding layer 6 are sequentially laminated, and Fe-InP buried layers 7 are formed on both sides of a semiconductor layer formed by these layers. A p-InP second cladding layer 8 and p-InGaAs are formed on the semiconductor layer and the Fe-InP buried layer 7.
The contact layer 9 and the SiO ₂ insulating film 10 are sequentially laminated. Reference numeral 11 denotes an electrode on which a Cr / Au evaporated film and an Au plating layer are laminated. Although not shown, on the back surface of the n-InP substrate 1,
An electrode is formed by stacking an AuGe / Ni / Ti / Pt / Au deposited film and an Au plating layer.

FIG. 12 is a perspective view showing a conventional semiconductor laser S2 used for electrical-optical conversion. The structure of the semiconductor laser S2 is basically the same as that of the optical modulator S1, and an n-InP buffer layer 2, an n-InGaAsP-SCH layer 3, and an InGa
MQW active layer 4a, p-InGaAsP-SCH layer 5, p-In in which As and InGaAsP are alternately stacked
A P-first cladding layer 6 is sequentially stacked, and a p-InP first block layer 12, an n-InP block layer 13, and a p-InP second block layer 14 are stacked on both sides of a semiconductor layer formed by these layers. ing. Further, further on these, the p-InP second cladding layer 8, p-In
A GaAs contact layer 9 and a SiO ₂ insulating film 10 are sequentially stacked. Reference numeral 11 denotes Cr / Au
2 shows an electrode on which a deposited film and an Au plating layer are stacked. Although not shown, an electrode in which an AuGe / Ni / Ti / Pt / Au deposited film and an Au plating layer are stacked on the back surface of the n-InP substrate 1 is formed.

Next, an optical modulator S1 and a semiconductor laser S
Operation 2 will be briefly described. First, the optical modulator S1
Then, when a reverse bias voltage is applied to the MQW absorption layer 4,
Due to the quantum confined Stark effect, the absorption spectrum of excitons shifts to longer wavelengths. Therefore, light incident from the outside is modulated by a change in light absorption due to the applied voltage.

On the other hand, in the semiconductor laser S2, when a forward current is injected into the MQW active layer 4a, when the injected current exceeds a threshold value, stimulated emission occurs and laser light is emitted. Since the intensity of the laser light changes depending on the magnitude of the injection current, an intensity-modulated optical signal can be obtained by modulating the injection current. In this way, various digital signals can be converted into light intensities.

[0007]

By the way, the optical modulator S
In 1, the absorbing layer 4 works as a parasitic capacitance. Therefore, in order to realize high-speed modulation, the modulator length L1 must be shortened (200 μ
m or less). Also,
In the semiconductor laser S2, there is a demand that the laser length L2 must be short (200 μm or less) in order to lower the threshold value and increase the efficiency.

However, if the lengths of the modulator length L1 and the laser length L2 are reduced to 200 μm or less, it becomes difficult to perform cleavage in the manufacturing process of the optical modulator S1 and the semiconductor laser S2. The widths W1 and W2 of the optical modulator S1 and the semiconductor laser S2 are usually 250 μm to 300 μm.
m and the thicknesses D1 and D2 are about 100 μm. Therefore, if the modulator length L1 and the laser length L2 are set to 200 μm or less, it becomes difficult to handle the optical modulator S1 and the semiconductor laser S2, and the steps during assembly will be difficult. There was an inconvenience of inviting a drop in the stay. As a result, there has been a problem that the product cost of the optical modulator S1 and the semiconductor laser S2, and furthermore, the product cost of a device using them increases.
Therefore, an object of the present invention is to provide a semiconductor optical device which can operate at high speed and can be applied to an optical communication system at low cost.

[0009]

According to a first aspect of the present invention, there is provided a semiconductor optical device having a pair of opposed end faces and an optical waveguide formed between the end faces. The total length of the element in the direction along which the light propagates is set to 250 μm or more, and the distance between the pair of end faces is set to 200 μm or less.

The semiconductor optical device according to the present invention (claim 2) has a light propagation in which a cross section cut by a virtual plane perpendicular to the length direction is formed in a substantially U-shape by laminating required semiconductor layers. And a semiconductor base not contributing to the semiconductor base, disposed at a central portion inside the semiconductor base formed in a substantially U-shaped cross section along a direction intersecting the length direction of the semiconductor base, and along the length direction of the semiconductor base. A pair of opposed end faces and a light propagation portion having an optical waveguide formed between the end faces, the length in the longitudinal direction of the semiconductor base is set to 250 μm or more, and the dimension between the end faces is 200 μm It is characterized in that it is set as follows.

In the semiconductor optical device according to the present invention (claim 3), in the semiconductor optical device according to claim 2, the semiconductor base portion and the light propagation portion are obtained by etching a part of the required semiconductor layer. It is characterized by being integrally formed.

A semiconductor optical device according to the present invention (claim 4) is characterized in that, in the semiconductor optical device according to any one of claims 1 to 3, an optical fiber is provided so as to face the end face. It is assumed that.

The semiconductor optical device according to the present invention (claim 5) is the semiconductor optical device according to claim 4, wherein the optical fiber is provided on the semiconductor base, and the semiconductor base has the end face and the end face. A proximity regulating surface for regulating the proximity of the end face of the optical fiber is formed.

[0014]

Embodiments of the present invention will be described below. Embodiment 1 FIG. FIG. 1 shows Embodiment 1 of the present invention. 1 is a perspective view of an optical modulator as a semiconductor optical device according to the first embodiment. Referring to FIG. 1, an optical modulator 20 includes a block-shaped semiconductor base 2.
1 and a light propagating portion 22 integrally formed therewith. The length 23 of the semiconductor base 21 in the length direction is 25
It is set to 0 μm. In the present embodiment, the dimension 23 is set to 250 μm, but may be changed appropriately as long as it is 250 μm or more.

The light propagation section 22 is a part that contributes to light propagation and functions as an optical modulator. A pair of end faces 24 are formed in the light propagation section 22. Note that, since FIG. 1 is a perspective view, only one end face 24 appears in the figure, and the other end face does not appear in the figure, but the other end face faces the back side of the one end face 24. Is formed. The length dimension 25 of the light propagation section 22, that is, the distance between the end faces is set to 200 μm. In the present embodiment, the dimension 25 is set to 200 μm, but may be changed as appropriate if it is 200 μm or less.

Hereinafter, the semiconductor base 21 and the light propagation section 22
The structure of will be described in detail. The semiconductor base 21 has a substantially U-shaped cross section, and is formed by stacking predetermined semiconductor layers. Specifically,
In the present embodiment, the semiconductor base 21 has an n-InP substrate 21a, and Fe-
InP layer 27, p-InP second cladding layer 28, pI
nGaAs contact layer 29 and SiO ₂ insulating film 30
Are sequentially laminated. In this embodiment, the thickness of each layer is such that the Fe-InP layer 27 has a thickness of 2.5 μm and the p-InP
The cladding layer 28 is set to 3.5 μm, the p-InGaAs contact layer 29 is set to 1.0 μm, and the SiO ₂ insulating film 30 is set to 0.2 μm.

The light propagation portion 22 is integrally formed with a so-called cross member at a central portion inside the semiconductor base portion 21 formed in a substantially U-shape. The light propagation unit 22 is formed by stacking predetermined semiconductor layers, like the semiconductor base 21. More specifically, in the present embodiment, the light propagating unit 22 is the n-In
Having an n-InP substrate 22a continuous with the P substrate 21a,
On this n-InP substrate 22a, an n-InP buffer layer 32, an n-InGaAsP-SCH layer 33, an InGaAs
light absorbing layer 3 on which s and InGaAsP are laminated
4, a p-InGaAsP-SCH layer 35 and a p-InP first cladding layer 36 are sequentially laminated.

These semiconductor layers (semiconductor layers indicated by reference numerals 32 to 36) form an optical waveguide through which light propagates, and Fe-InP layers 27 are formed on both sides of the semiconductor layer. I have. Furthermore, a p-InP second cladding layer 28 and a p-InGa
As contact layer 29 and SiO ₂ insulating film 30 are sequentially laminated. Note that these Fe-InP layers 27, p
The -InP second cladding layer 28, the p-InGaAs contact layer 29, and the SiO ₂ insulating film 30 are respectively composed of the Fe-InP layer 27, the p-InP second cladding layer 28, and the p-InGaAs contact layer 29 of the semiconductor base 21.
And formed continuously and integrally with the SiO ₂ insulating film 30.

In the present embodiment, the thickness of each layer forming the optical waveguide is 0.2 μm for the n-InP buffer layer 32 and 50 μm for the n-InGaAsP-SCH layer 33.
The MQW light absorption layer 34 in which InGaAs and InGaAsP are laminated is 9 nm (InGaAs: 3 nm,
InGaAsP: 6 nm), p-InGaAsP-SC
The H layer 35 is set to 50 nm, and the p-InP first cladding layer 36 is set to 0.2 μm.

In addition, reference numeral 41 indicates an electrode on which a Cr / Au evaporated film and an Au plating layer are laminated.
Although not shown, an electrode in which an AuGe / Ni / Ti / Pt / Au vapor deposition film and an Au plating layer are stacked is formed on the back surface of the n-InP substrate 21a.

Next, a method for manufacturing the optical modulator 20 will be described with reference to FIGS. FIG. 2 is a front view as seen from the direction of arrow I in FIG. Referring to FIG. 2A, first, MOCVD is performed on n-InP substrate 21a.
N-InP buffer layer 32, n-InGa
AsP-SCH layer 33, InGaAs / InGaAsP
-MQW active layer 34, p-InGaAsP-SCH layer 3
5, a p-InP first cladding layer 36 is sequentially formed. The thickness of each layer is as described above.

Next, referring to FIG. 2B, a semiconductor layer (ridge mesa) serving as a core of the light propagation section 22 is formed by etching. The width of the semiconductor layer (the width of the mesa) is
In the present embodiment, it is set to about 1 μm. As the etching process in this case, for example, wet etching using HBr can be employed.

Referring to FIG. 2 (c), the MOCV
The Fe—InP layers 27 are formed on both sides of the semiconductor layer by the D method or the like.

Referring to FIG. 2 (d), these F
A p-InP second cladding layer 28 and a p-InGaAs contact layer 29 are sequentially stacked on the entire upper surface of the e-InP layer 27 and the like by MOCVD or the like.

FIG. 3 is a perspective view showing the semiconductor layer (an intermediate of the optical modulator 20) formed as described above.

Next, an arrow III surrounded by a dashed line in FIG.
An etching process is performed on the portion indicated by. Specifically, a portion surrounded by a dashed line of the formed semiconductor layer is removed by wet etching using bromomethanol, wet etching using HCl, or dry etching using methane and hydrogen. As a result, FIG.
As shown in (1), the semiconductor base 21 and the light propagation unit 22 are formed. The etching depth at this time is preferably such that the n-InGaAsP-SCH layer 33 is removed.

Next, as shown in FIG. 1, after the SiO ₂ insulating film 30 is formed by a sputtering method or the like, a portion of the SiO ₂ insulating film 30 corresponding to the portion where the electrode 41 is to be formed is removed by etching. . As an etching process in this case, wet etching using HF or the like can be employed. Subsequently, Cr / A is formed by sputtering or the like.
After forming the u-deposited film, the Au plating layer is patterned. Further, AuGe / Ni is formed on the back surface of the semiconductor base 21a.
After forming a / Ti / Pt / Au deposited film, an Au plating layer is patterned. Thus, the formation of the electrode 41 and the like is completed.

Thereafter, the wafer is cleaved into strips, anti-reflection films are formed on both end surfaces of the light propagation portion 22 formed by etching, and then dicing separation is performed to complete the light modulator 20 shown in FIG. I do.

In FIG. 1, dry etching is employed as an etching process for a portion surrounded by a dashed line shown in FIG. 3, and the SiO ₂ film used as the etching mask is directly used as a SiO ₂ film for forming the next electrode. _The embodiment used as _two films is shown.

According to the optical modulator 20 according to the present embodiment, the distance 25 between the end faces 24 of the light propagation section 22 is set to 200 μm
Since the following can be set, the parasitic resistance of the optical modulator 20 can be reduced. That is, the length dimension 2 of a portion contributing to light propagation of the optical modulator 20, that is, a portion contributing to conversion of a digital signal into an optical signal in an optical communication system.
Since 5 can be set to 200 μm or less, the parasitic resistance of the optical modulator 20 can be reduced, and as a result, the optical modulator 20 that can operate at high speed can be provided. Moreover, since the length 23 of the optical modulator 20 in the longitudinal direction can be set to 250 μm or more, there is an advantage that the handling of the optical modulator 20 becomes easy and the production efficiency can be increased.

Therefore, it is possible to provide the optical modulator 20 which can operate at high speed and is applicable to the optical communication system at low cost, and furthermore, it is possible to provide the optical device using the optical modulator at low cost. This has the effect.

Further, in the present embodiment, since the semiconductor base 21 and the light propagating portion 22 are formed by etching, the end face 24 can be formed very easily and well. Therefore, the manufacture of the optical modulator 20 becomes easy,
There is an advantage that the cost can be further reduced.

In the present embodiment, a modification as shown in FIG. 4 is conceivable. FIG. 4 is a perspective view of an optical modulator 20 according to a modification of the present embodiment. Referring to FIG.
An optical modulator 20 according to this modification is obtained by attaching optical fibers 40 and 42 to the optical modulator 20 shown in FIG.
In this modification, the optical fiber 40 is for guiding light from the outside to the optical modulator 20, and the optical fiber 42 is for extracting light from the optical modulator 20 to the outside.

The optical fibers 40 and 42 have a concave portion 45 formed by etching in FIG.
(See FIG. 1), and the optical fiber 40,
The end face 42 and the end face 24 of the light propagation section 22 are arranged to face each other. That is, the core portions of the optical fibers 40 and 42 are arranged along the direction of light input to and output from the InGaAs / InGaAsP-MQW active layer 34 of the optical modulator 20.

For bonding the optical fibers 40 and 42 to the optical modulator 20, an adhesive such as an epoxy resin can be used. Note that the shape of the concave portion 45 can be changed as appropriate in accordance with the outer shape of the optical fibers 40 and 42, whereby the optical fibers 40 and 42 can be reliably engaged. The size of the concave portion 45 can be set, for example, to a width of 100 to 150 μm, a depth of 5 to 50 μm, and a depth (total length of chip−length of modulator) of 50 μm.

According to this modification, there is an advantage that the optical axes of the optical modulator 20 and the optical fibers 40 and 42 can be easily and reliably aligned.

Further, as shown in FIG. 5, the concave portion 45 may have a stepped shape. By forming the concave portion 45 in such a shape, a kind of contact surface 43 (proximity regulating surface) is formed in the step portion. The contact surface 43 can have a structure in which the end surfaces of the optical fibers 40 and 42 do not contact the end surface 24 of the optical modulator 20 when the optical fibers 40 and 42 are arranged in the recess 45. Accordingly, there is an advantage that the mechanical shock from the optical fibers 40 and 42 does not directly reach the optical modulator 20 and the reliability of the optical modulator 20 can be improved by preventing the optical modulator 20 from being damaged.

Embodiment 2 Next, Embodiment 2 of the present invention. Will be described. FIG. 6 shows Embodiment 2 of the present invention. 1 is a perspective view of a semiconductor laser as a semiconductor optical device according to the first embodiment. Referring to FIG. 6, a semiconductor laser 50 has a block-shaped semiconductor base portion 51 and a light propagation portion 52 integrally formed therewith. The length 53 in the length direction of the semiconductor base 51 is set to 250 μm. Note that the dimension 53 may be appropriately changed as long as it is 250 μm or more.

The light propagation section 52 is a part that contributes to light propagation and functions as a semiconductor laser. A pair of resonator end faces 54 are formed in the light propagation section 52. Since FIG. 6 is a perspective view, only one resonator end face 54 is shown in the drawing, and the other resonator end face is not shown in the drawing, but the other resonator end face is one resonator end face. 54 are formed so as to face the rear surface side.
The length 55 of the light propagation portion 52, that is, the distance between the cavity end faces is set to 200 μm. In addition, the dimension 55 may be appropriately changed as long as it is 200 μm or less.

Hereinafter, the semiconductor base portion 51 and the light propagation portion 52
The structure of will be described in detail. The semiconductor base 51 has a substantially U-shaped cross section cut along a virtual plane along the length direction, and is configured by stacking predetermined semiconductor layers. More specifically, in the present embodiment, the semiconductor base 51 has an n-InP substrate 51a.
A p-InP first current blocking layer 57a, an n-InP current blocking layer 57b, and a p-In
P second current blocking layer 57c, p-InP second cladding layer 58, p-InGaAs contact layer 59, and S
iO ₂ insulating films 60 are sequentially stacked. In the present embodiment, the thickness of each layer is 1.0 μm for the p-InP first current blocking layer 57a and 1.0 μm for the n-InP current blocking layer 57b.
Is 1.0 μm, the p-InP second current blocking layer 57c is 1.0 μm, and the p-InP second cladding layer 58 is 3.5 μm.
m, p-InGaAs contact layer 59 is 1.0 μm,
And the thickness of the SiO ₂ insulating film 60 is set to 0.2 μm.

The light propagation portion 52 is formed integrally with a so-called cross member from the center to the end inside the semiconductor base 51 formed in a substantially U shape. The light propagation section 52 is formed by stacking predetermined semiconductor layers, like the semiconductor base section 51. More specifically, in the present embodiment, the light propagation unit 52 includes the n-InP buffer layer 52a and the n-InGaAsP on a substrate common to the n-InP substrate 51a of the semiconductor base 51.
-SCH layer 53, MQW active layer 54 in which InGaAs and InGaAsP are stacked, p-InGaAsP-S
The CH layer 55 and the p-InP first cladding layer 56 are sequentially laminated.

These semiconductor layers (semiconductor layers indicated by reference numerals 52a to 56) form a core portion of an optical waveguide through which light propagates, and current blocking layers are formed on both sides of the semiconductor layer. ing. This current blocking layer is formed by the above p
It is composed of a -InP first current block layer 57a, an n-InP current block layer 57b, and a p-InP second current block layer 57c.

Further, on the current blocking layer,
The p-InP second cladding layer 58, the p-InGaAs contact layer 59, and the SiO ₂ insulating film 60 are sequentially laminated. The current blocking layer, the p-InP second cladding layer 58, and the p-InGaAs contact layer 59
And the SiO ₂ insulating film 60 are respectively formed by the p-InP first current blocking layers 57 a and n-I of the semiconductor base 51.
nP current blocking layer 57b, p-InP second current blocking layer 57c, p-InP second cladding layer 58, p-In
GaAs contact layer 59 and SiO ₂ insulating film 60
Are formed continuously and integrally.

Further, in the present embodiment, the thickness of each layer forming the core portion of the optical waveguide is such that the n-InP buffer layer 52a has a thickness of 0.2 μm and the n-InGaAsP-SCH layer 5 has a thickness of 0.2 μm.
3 is 50 nm, and the MQW active layer 54 in which InGaAs and InGaAsP are stacked is 9 nm (InGaAs: 3
nm, InGaAsP: 6 nm), p-InGaAsP
The SCH layer 55 is set to 50 nm, and the p-InP first cladding layer 56 is set to 0.2 μm.

In addition, reference numeral 41 denotes an electrode on which a Cr / Au evaporated film and an Au plating layer are laminated.
Although not shown, an electrode in which an AuGe / Ni / Ti / Pt / Au vapor deposition film and an Au plating layer are stacked is formed on the back surface of the n-InP substrate 51a.

Next, a method for manufacturing the semiconductor laser 50 will be described with reference to FIGS. FIG. 7 shows FIG.
5 is a front view as viewed from the direction of arrow I. FIG.
With reference to (a), first, M
The n-InP buffer layer 52a, n
-InGaAsP-SCH layer 53, InGaAs / In
GaAsP-MQW active layer 54, p-InGaAsP-
The SCH layer 55 and the p-InP first cladding layer 56 are sequentially formed. The thickness of each layer is as described above.

Referring to FIG. 7B, a semiconductor layer (ridge mesa serving as a core of the optical waveguide) serving as a core of the light propagation section 22 is formed by etching. The width of the semiconductor layer (mesa width) is set to about 1 μm in this embodiment. As the etching process in this case, for example, wet etching using HBr can be adopted.

Referring to FIG. 7 (c), the MOCV
The current blocking layers (p-InP first current blocking layer 57a, n-InP current blocking layer 57b, p-InP second current blocking layer 5) are formed on both sides of the semiconductor layer by the D method or the like.
7c) is formed.

Referring to FIG. 7 (d), a p-InP second cladding layer 58,
And p-InGaAs contact layer 59 by MOCVD
The layers are sequentially laminated by a method or the like.

FIG. 8 is a perspective view showing the semiconductor layer (an intermediate of the semiconductor laser 50) formed as described above.

Next, an arrow III surrounded by a chain line in FIG.
An etching process is performed on the portion indicated by. Specifically, a portion surrounded by a dashed line of the formed semiconductor layer is removed by wet etching using bromomethanol, wet etching using HCl, or dry etching using methane and hydrogen. As a result, FIG.
As shown in (1), a semiconductor base 51 and a light propagation section 52 are formed. The etching depth at this time is preferably such that the n-InGaAsP-SCH layer 53 is removed.

Next, as shown in FIG. 6, after the SiO ₂ insulating film 60 is formed by a sputtering method or the like, a portion of the SiO ₂ insulating film 60 corresponding to the portion where the electrode 41 is to be formed is removed by etching. . Then, after forming a Cr / Au vapor deposition film by a sputtering method or the like, an Au plating layer is patterned. Further, A is attached to the back surface of the semiconductor base 51a.
After forming a uGe / Ni / Ti / Pt / Au deposited film,
An Au plating layer is patterned. Thereby, the electrode 4
The formation of 1 etc. is completed.

Thereafter, the wafer is cleaved into strips, an antireflection film is formed on the cleaved end face and the other end face formed by etching, and then dicing separation is performed.
The semiconductor laser 50 shown in FIG. 6 is completed.

According to the semiconductor laser 50 of the present embodiment, the distance 25 between the cavity end faces 54 of the light propagation section 52 is set to 2
Since the thickness can be set to be equal to or less than 00 μm, the parasitic resistance of the semiconductor laser 50 can be reduced. That is, the length 55 of a portion contributing to light propagation of the semiconductor laser 50, that is, a portion contributing to conversion of a digital signal into an optical signal in an optical communication system can be set to 200 μm or less. The resistance can be reduced, and as a result, a semiconductor laser 50 that can operate at high speed can be provided. In addition, since the length 53 of the semiconductor laser 50 in the longitudinal direction can be set to 250 μm or more, there is an advantage that the handling of the semiconductor laser 50 becomes easy and the production efficiency can be improved.

Therefore, it is possible to provide the semiconductor laser 50 which can operate at high speed and is applicable to the optical communication system at low cost, and thus, it is possible to provide the optical device using the semiconductor laser at low cost. There is an effect that can be.

Further, in this embodiment, since the semiconductor base portion 51 and the light propagation portion 52 are formed by the etching process, the cavity end face 54 can be formed very easily and well. Therefore, there is an advantage that the manufacture of the semiconductor laser 50 is facilitated and the cost can be further reduced.

In the present embodiment, a modified example as shown in FIG. 9 is conceivable. FIG. 9 is a perspective view of a semiconductor laser 50 according to a modification of the present embodiment. Referring to the figure, a semiconductor laser 50 according to this modification is obtained by attaching an optical fiber 40 to the semiconductor laser 50 shown in FIG.

The optical fiber 40 is fitted into a concave portion 65 (see FIG. 6) formed by performing the etching process in FIG. 8, and the end face of the optical fiber 40 and the resonator end face 54 of the light propagation section 52 are connected. They are arranged facing each other.
That is, the core of the optical fiber 40 is
Are arranged along the direction of light input to and output from the InGaAs / InGaAsP-MQW active layer 54.

For bonding the optical fiber 40 and the semiconductor laser 50, for example, an adhesive such as an epoxy resin can be used. The dimensions of the recess 65 are, for example, 100 to 150 μm in width, 50 μm in depth, and 50 μm in depth.
(The total length of the semiconductor laser 50-the length of the laser portion resonator). At this time, if an optical fiber having a radius of about 40 to 50 μm is used, the optical axis of the active layer 54 and the core of the optical fiber 40 can be easily aligned. In addition, the shape of the concave portion 65 can be appropriately changed in accordance with the outer shape of the optical fiber 40, and thereby the optical fiber 40 can be securely engaged.

According to this modification, there is an advantage that the optical axis of the semiconductor laser 60 and the optical fiber 40 can be easily and reliably aligned.

Further, as shown in FIG. 10, the concave portion 65 may have a stepped shape. By forming the concave portion 65 in such a shape, a kind of contact surface 63 (proximity regulating surface) is formed in the step portion. The contact surface 63 can have a structure in which the end face of the optical fiber does not contact the resonator end face 54 of the semiconductor laser 50 when the optical fiber is disposed in the recess 65. Accordingly, there is an advantage that the mechanical shock from the optical fiber does not directly affect the semiconductor laser 50, and the semiconductor laser 50 can be prevented from being damaged, and the reliability can be improved.

In the present embodiment, the semiconductor laser is formed on the n-type substrate, but may be formed on the p-type substrate. After forming the p or n-type contact layer on the semi-insulating substrate, the semiconductor laser unit may be formed.

In this embodiment, the example of the Fabry-Perot type semiconductor laser has been described.
A B laser or a DBR laser may be used.

[0064]

According to the first aspect of the present invention, the length of a portion contributing to light propagation of a semiconductor optical device, that is, a portion contributing to conversion of a digital signal into an optical signal in an optical communication system is determined. Because it is set to 200μm or less,
The parasitic resistance of the semiconductor optical device can be reduced. Further, since the total length of the device is set to 250 μm or more, the handling of the semiconductor optical device becomes easy, and the production efficiency can be improved. Thus, a semiconductor optical device that can operate at high speed and can be applied to an optical communication system can be provided at low cost.

According to the second aspect of the present invention, since the total length of the semiconductor base is set to 250 μm or more, the handling of the semiconductor optical device becomes easy and the production efficiency can be improved. Further, the distance between the cavity end faces of the light propagating section is set to 200.
Since the thickness is set to μm or less, the parasitic resistance of the semiconductor optical device can be reduced. Thus, a semiconductor optical device that can operate at high speed and can be applied to an optical communication system can be provided at low cost.

According to the third aspect of the invention, the same operation and effect as those of the second aspect of the invention can be obtained. In particular, in the invention according to the present invention, since the semiconductor base and the light propagation portion are formed by the etching process, the formation of the end face is extremely easy. Therefore, the manufacture of the semiconductor optical device is facilitated, and the semiconductor optical device applicable to the optical communication system can be provided at lower cost.

According to the fourth aspect of the invention, the same functions and effects as those of the first to third aspects of the invention are obtained. In addition, in the invention according to the present claim, since the optical fiber is provided, there is an advantage that a semiconductor optical device applicable to an optical communication system can be provided at low cost.

According to the fifth aspect of the invention, the same operation and effect as those of the fourth aspect of the invention can be obtained. In particular, in the invention according to the present claim, the proximity regulating surface can prevent the end face and the end face of the optical fiber from approaching more than necessary. That is, since the end face and the optical fiber can be kept in a non-contact state, it is possible to prevent the semiconductor optical element from being damaged due to the contact between the two. As a result, the performance and reliability of the semiconductor optical device can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical modulator according to Embodiment 1 of the present invention.

FIGS. 2A to 2D show a part of a manufacturing process of the optical modulator according to the first embodiment of the present invention in the order of FIGS.

FIG. 3 is a perspective view of an intermediate in a manufacturing process of the optical modulator according to Embodiment 1 of the present invention.

FIG. 4 is a perspective view of an optical modulator according to a modification of the first embodiment of the present invention.

FIG. 5 is a perspective view of an optical modulator according to another modification of the first embodiment of the present invention.

FIG. 6 is a perspective view of a semiconductor laser according to a second embodiment of the present invention.

FIGS. 7A to 7D show a part of a manufacturing process of a semiconductor laser according to a second embodiment of the present invention in the order of FIGS.

FIG. 8 is a perspective view of an intermediate in a manufacturing process of the semiconductor laser according to Embodiment 2 of the present invention;

FIG. 9 is a perspective view of a semiconductor laser according to a modification of the second embodiment of the present invention.

FIG. 10 is a perspective view of a semiconductor laser according to another modification of the second embodiment of the present invention.

FIG. 11 is a perspective view showing a structure of a conventional optical modulator.

FIG. 12 is a perspective view showing a structure of a conventional semiconductor laser.

[Description of Signs] 20 optical modulator, 21 semiconductor base, 22 light propagation unit,
23 length dimension, 24 end face, 25 distance between resonator end faces, 43 contact face, 50 semiconductor laser, 51 semiconductor base, 52 light propagation section, 53 length dimension, 54
Resonator end face 55 Distance between resonator end faces, 63 Contact face.

Claims (5)

[Claims] 1. A semiconductor optical device having a pair of opposed end faces and an optical waveguide formed between the end faces, the total length of the element in a direction along which light propagates through the optical waveguide is set to 250 μm or more; The distance between the pair of end faces is set to 200 μm or less. 2. A semiconductor base that does not contribute to light propagation, wherein a cross section cut by an imaginary plane orthogonal to the length direction is formed in a substantially U-shape by laminating required semiconductor layers; The semiconductor base is formed at a central portion inside the semiconductor base along a direction intersecting with the length direction of the semiconductor base, and is formed between a pair of end surfaces facing each other along the length direction of the semiconductor base and the end surface. A length of the semiconductor base portion in the longitudinal direction is set to 250 μm or more, and a dimension between the end faces is set to 200 μm or less. Optical element. 3. The semiconductor optical device according to claim 2, wherein the semiconductor base and the light propagation unit are integrally formed by etching a part of the required semiconductor layer. Semiconductor optical device. 4. The semiconductor optical device according to claim 1, wherein an optical fiber is provided so as to face the end face. 5. The semiconductor optical device according to claim 4, wherein the optical fiber is provided on the semiconductor base, and the semiconductor base restricts the end face and the end face of the optical fiber from approaching each other. A semiconductor optical device having a proximity regulating surface.