JPH09289354A - Semiconductor laser element and optically coupled device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser element which has a large spot size in a horizontal direction with respect to a substrate and enables generation of a low-threshold current and a high output. SOLUTION: An n-type InGaAsP confinement layer 102, a multiple quantum well active layer 103, a p-type InGaAsP confinement layer 104 and a p-type InP clad layer 105 are formed in a mesa shape on an n-type InP substrate 101, thereby forming a stripe with respect to the direction of a resonator. On both lateral sides thereof, current block layers 106, 107 are embedded. The width of the stripe 114 including the active layer 103 of the laser is changed with respect to the direction of the resonator. A width W1 of the stripe in a region A near a front end surface is set to be equivalent to the spot size of a light propagated on an optical waveguide. A width W2 of the stripe in a region C of a distance L from a rear end surface is so set as to perform transverse mode single oscillation. A width of the stripe in a region B is continuously changed in a tapered shape. Thus, a semiconductor laser element having a large spot size in the horizontal direction with respect to the substrate and having a low threshold current and a high output may be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupling device for optically coupling an optical fiber which is a transmission path and a semiconductor laser element which is a light source in so-called optical fiber communication for transmitting an optical signal using an optical fiber. The present invention relates to a semiconductor laser device.

[0002]

2. Description of the Related Art In recent years, an optical subscriber system for transmitting data and multi-channel video information from a center station to general households using optical fibers has been proposed and studied.
These systems require a plurality of light-receiving devices for simultaneously receiving different types of optical signals wavelength-division-multiplexed to subscriber terminals in general homes, and a light-emitting device for sending requests and data from homes to the center. Become.

For example, as an optical coupling device used for this type of purpose, there is a reference (I. Ikushima et al., "High-perform").
ance compact optical WDM transceiver module for pa
ssive double star subscriber systems, "Journal of
Lightwave Technology, vol. 13, No. 3, p517 ~, 199
In 5), the one shown in FIG. 8 is proposed.

The structure of the optical coupling device shown in FIG. 8 is as follows. PLC (Planar Lig
htwave Circuit) An optical circuit 804 is formed, and an optical fiber 802 is connected to a transmission line for transmitting a bidirectional optical signal having a wavelength of 1.3 μm and an optical signal having a wavelength of 1.55 μm.
And an optical fiber 8 for extracting an optical signal with a wavelength of 1.55 μm
03 is connected. The optical signal from the outside has a wavelength of 1.
A semiconductor light receiving element 805 that detects an optical signal of 3 μm is detected, and an external optical signal is generated by a lens 806 and a semiconductor laser element 807 placed outside the PLC circuit.

The PLC optical circuit 804 has a wavelength of 1.3 μm.
Mach-Zehnder type wavelength demultiplexer 8 capable of demultiplexing an optical signal of m and an optical signal of 1.55 μm
08 and a semiconductor light receiving element 805 for detecting a signal transmitted by branching an optical signal of 1.3 μm into 50% each.
The optical branching device 809 connects the other to a semiconductor laser device 807 that transmits an optical signal.

[0006]

In the conventional optical coupling device, the wavelength demultiplexing element 8 arranged on the PLC optical circuit 804 is used.
The position of the optical waveguide connecting each element such as 08 and the optical branching device 809 is accurate, and an optical waveguide with low loss can be expected.

However, in this optical coupling device, the light emitting element, the PLC optical circuit 804, the PLC optical circuit 804, and the optical fibers 802 and 803 are made of different materials,
It is necessary to connect the optical fibers 802 and 803, which are transmission lines, and the substrate having the optical waveguide so as to be optically coupled.

This connection requires adjustment with a very high accuracy of several μm in the three-dimensional direction, and at the same time requires a connection with long-term reliability, which requires a complicated assembly process and is not always economical. Can not be expected.

Further, there is a problem that the connecting process of optical fibers tends to become difficult as the number of optical fibers taken out from the substrate increases. Therefore, a low-cost and highly reliable optical coupling device such as an optical subscriber transmission system is required. This is a major issue toward the practical application of the required system.

A lens 806 is used to couple the semiconductor laser device 807 and the PLC optical circuit 804. Although this method can increase the coupling efficiency, it not only increases the number of parts, but also increases the number of parts in the semiconductor laser element 807 and the lens 8.
The optical axes of both 06 must be adjusted in the three-axis directions, resulting in a problem that the assembly process becomes very complicated and the cost reduction is hindered.

Particularly, the latter problem occurs because the positioning allowance is small when the semiconductor laser device and the optical waveguide are directly coupled, and the problem can be solved by increasing the positioning allowance. Furthermore, if an optical fiber is used as the optical waveguide, the former problem can be solved.

Therefore, calculation (J. Sakai et al .; IEEE J
ournal of Quantum Electronics, Vol. QE-16, No.10,
p1059-, 1980), the relationship between the coupling efficiency and the positioning tolerance with respect to the spot diameter of the semiconductor laser and the optical waveguide in the optical coupling device is estimated as shown in FIG. 4 (however, in this calculation, the spot is the semiconductor laser). , Assuming that both optical waveguides are circular).

It can be seen from FIG. 4 that in the optical coupling device, the closer the spot diameters are to each other, the higher the coupling efficiency is. Further, it can be seen that the positioning allowance also increases as the spot diameters are closer to each other.

Generally, the spot diameter of the semiconductor laser is smaller than that of the spot of the optical waveguide. Therefore, as a method of solving the above-mentioned problem, it is considered to increase the spot diameter of the semiconductor laser.

Therefore, as a method for solving the problem, a reference (P. Doussiere et al .; Applied Physics. Lette) has been used so far in order to increase the spot diameter of a semiconductor laser.
rs Vol.64, No.31, p539-, 1994), a method using a structure as shown in FIG. 9 is proposed.

However, according to this method, the stripe width of the active layer is narrowed to reduce the effect of optical confinement so that the spot of the semiconductor laser is enlarged in a nearly circular shape, so that the gain in the active layer is small and the threshold current is small. Becomes higher, which causes a problem that output power is difficult to obtain.

Further, when the spot diameter is increased by narrowing the stripe width of the active layer to reduce the effect of light confinement, what is the normal distribution which is a typical intensity distribution of the spot of an optical fiber or a general semiconductor laser? There is also a problem that different intensity distributions (Gaussian distributions) are displayed, which causes deterioration of coupling efficiency.

In view of the above, the present invention provides a semiconductor laser device having a new structure and an optical coupling device using the same in order to realize easier and more economical mounting and assembly of the optical coupling device. To aim.

[0019]

In order to solve all of the above problems, the present invention provides a semiconductor laser element in an optical coupling device, which has a stripe-shaped active layer of a semiconductor laser as shown in FIG. 1 (c). We propose a structure in which the front end face for generating a laser beam is enlarged to a spot diameter of light propagating in the optical waveguide.

In the present invention, the drawbacks of narrowing the active layer of a semiconductor laser are solved, and an elliptical, normally distributed spot having a low threshold current and high output and a large spot diameter in the horizontal direction with respect to the substrate is obtained. A semiconductor laser having an intensity distribution can be realized.

As shown in FIG. 5, the spot diameters of the semiconductor laser and the optical fiber as the optical waveguide in the horizontal direction with respect to the substrate are WLX and WOX, and the spot diameters with respect to the substrate are WLY and WOY. Furthermore, the horizontal coupling efficiency and positioning tolerance are EX and TX, and the vertical coupling efficiency and positioning tolerance are EY and TY.

At this time, when EX, TX, EY, TY are obtained from FIG. 4, when the semiconductor laser device shown in FIG. 9 is used,
It is almost circular with a maximum of WLX = WLY = 4.0 μm, and the optical waveguide is a single mode optical fiber (spot diameter WOX = WOY = 10 μm
m), the coupling efficiency is EX = EY = 0.69, and the overall coupling efficiency is E, then E = EX · EY = 0.48 (however, the optical fiber spot diameter and the optical fiber core in the text are Diameter is synonymous).

The relationship between the positional deviation of the semiconductor laser element with respect to the optical fiber and the coupling efficiency at that time is shown by the broken line in FIG. 6 from the calculation, and the coupling efficiency is 3d from the peak.
Positioning tolerance when B is lowered is TX = TY = ± 3.2
It is about μm.

On the other hand, from the calculation results shown in FIG. 7, when considering coupling with a single-mode optical fiber, the spot diameter of the conductor laser element in the present invention is WLX = 10 μm, WLY = 2.4.
μm, the coupling efficiency with the above single mode optical fiber is EX = 1.0, EY = 0.45, and the overall coupling efficiency E is E =
EX ・ EY = 0.45.

The relationship between the positional deviation of the semiconductor laser element with respect to the optical fiber and the coupling efficiency at that time is shown by the solid line in FIG. 6 from the calculation, and the coupling efficiency is 3d from the peak.
Positioning tolerance when B is lowered is TX = ± 4.2μm,
TY = ± 3.0μm.

From the above calculation results, even in the method of increasing the spot size in the elliptical shape only in the horizontal direction with respect to the substrate as in the present invention, the coupling efficiency and verticality are the same as those in the method of increasing the spot size in the circular shape. It can be seen that directional positioning tolerances are obtained, and even greater horizontal positioning tolerances.

Further, when considering an optical coupling device in which the semiconductor laser element and the optical waveguide of the present invention are arranged on the same substrate as shown in FIG. 2, the positioning accuracy is necessarily in the vertical direction with respect to the substrate. Therefore, it is very advantageous to use a semiconductor laser device having a large positioning allowance in the horizontal direction with respect to the substrate as in the present invention.

Therefore, when the embodiment as shown in FIG. 2 is adopted, an optical coupling device for highly efficiently coupling the semiconductor laser and the optical waveguide without the highly accurate positioning and the complicated assembling process as in the past is adopted. It becomes possible to manufacture the optical coupling device at low cost and with high reliability.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention and their effects will be described below with reference to FIGS.

(Embodiment 1) FIG. 1A is a diagram of a front end face portion of a semiconductor laser device according to a first embodiment of the present invention.
1 (b) is a view of the rear end face portion of the semiconductor laser device of the first embodiment of the present invention, and FIG. 1 (c) is a perspective view seen from above the semiconductor laser device of the first embodiment of the present invention. Yes, the internal structure is made clear. The semiconductor laser of the present invention is
The oscillation wavelength is around 1.3 μm.

The structure of the semiconductor laser of the present invention is an n-type InP
N-type InGaAsP optical confinement layer (thickness 150 nm,
λg = 1.0 μm) 102, multiple quantum well active layer 103, p-type
InGaAsP optical confinement layer (thickness 30 nm, λg = 1.05 μm) 10
4. A p-type InP clad layer (thickness 400 nm) 105 is formed in a mesa shape and extends in a stripe shape in the resonator direction.

Further, both sides of these are buried with a p-type InP current blocking layer 106 and an n-type InP current blocking layer 107, and a p-type InP buried layer 108 and a p-type InP current blocking layer 107 are provided above them.
An InGaAsP contact layer (λg = 1.05 μm) 109 is formed.

An n-type electrode 110 made of an Au / Sn alloy is formed on the back surface of the n-type InP substrate 101, and a p-type InGaAsP contact layer 109 has a stripe-shaped window on top of the Si.
The O2 insulating film 111 is formed, and the electrode 112 made of Au / Zn alloy formed on the O2 insulating film 111 is formed by using the SiO2 insulating film 111.
Through the striped window of the above, and is in contact with the p-type InGaAsP contact layer 109. Furthermore, Ti is formed on the electrode 112.
A p-type electrode 113 made of / Au alloy is formed.

The multiple quantum well active layer 103 is 0.7
% Of the InGaAsP well layer having a thickness of 6 nm in which compressive strain is introduced and an InGaAsP barrier layer (λg = 1.05 μm) having a thickness of 10 nm in which no strain is intentionally introduced.

The length of the laser resonator is 300 μm or more, and the width of the stripe 114 including the active layer 103 changes with respect to the resonator direction. 25μ from the front facet of the laser
The stripe width W1 in the area A of m is set to be approximately the same as the spot diameter of light propagating in the optical waveguide, and assuming that the optical waveguide is a commercially available single-mode optical fiber (spot diameter of approximately 10 μm), The stripe width W1 is about 10 μm from the calculation result of the waveguide analysis shown in FIG.

Further, when the semiconductor laser device of the present invention is used for optical communication, performances such as low noise and low distortion are essential. Therefore, the semiconductor laser must be oscillated in a single transverse mode. Therefore, in the present invention, the length L from the rear end face is set so that the semiconductor laser oscillates in a single transverse mode.
The stripe width W2 in the region C of 1.0 to 1.5 μm
I will set it to m. And in the remaining area B,
To increase the spot diameter, the stripe width is tapered up to W2 toward the front end face.

The shape of the taper region may be linear (first-order function) or non-linear (second-order or higher function). In order to eliminate the propagation loss of light in the region B, it is necessary to lengthen the region B to some extent in the case of a linear case.
In the case of non-linearity, the length of the region B can be relatively short.

In order to reduce the margin at the time of cleavage and the loss in the region B, the region A having a length of several tens of μm to 100 μm and a constant width W2 is provided.

The length L from the rear end face described above is set to 200 μm or more so that the semiconductor laser oscillates in a single transverse mode, the threshold current is sufficiently small, and a high output is obtained. .

Further, in order to promote single transverse mode oscillation,
No electrodes are attached to the stripe width of 2 μm or more where high-order mode is likely to occur so that no current is injected.

In the present embodiment, the front end face and the rear end face of the laser are cleaved faces, but in order to reduce the threshold current and increase the output power, 2
One or both of the two end faces may be highly reflective coated.

Further, although the oscillation wavelength is in the 1.3 μm band in this embodiment, it may be in the 1.55 μm band and other wavelengths by changing the composition of the material. Further, in this embodiment, a laser having a Fabry-Perot resonator is used, but a distributed feedback semiconductor laser (DFB laser) in which a diffraction grating is formed near the active layer (for example, a substrate near the active layer) may be used.

(Embodiment 2) FIG. 2A is a sectional view of an optical coupling device according to a second embodiment of the present invention, and FIG. 2B shows an optical coupling device according to the second embodiment of the present invention. It is a top view.

In the structure of the present invention, the semiconductor laser device 202 of the present invention and the single mode optical fiber 203 which is an optical waveguide are arranged on the substrate 201 so as to face each other.
01 is processed so that each optical axis has the same height. Further, with respect to the single mode optical fiber 203, a groove-shaped fiber alignment groove 204 is formed in the substrate 201 so that the position can be fixed to the substrate 201 in both horizontal and vertical directions without adjustment.

The shape of the fiber alignment groove 204 is V-shaped, U-shaped or rectangular so that the position of the core 205 of the single mode optical fiber can be uniquely determined without adjustment. The surface of the optical fiber 204 that supports the optical fiber must be flat and parallel to the cavity direction of the semiconductor laser.

In this embodiment, since the substrate 201 is processed, the semiconductor laser 202 and the optical fiber 203 can be arranged very accurately in the direction perpendicular to the substrate.

Since the optical fiber 203 can be accurately positioned in the horizontal direction with respect to the substrate, the coupling efficiency between the semiconductor laser 202 and the optical fiber 203 largely depends on the positioning tolerance of the semiconductor laser 202.

FIG. 6 shows the core of an optical fiber in two types of semiconductor lasers having the same coupling efficiency as described above.
This is a calculation of the coupling efficiency with respect to the horizontal and vertical misalignment between the center of 205 and the center of the semiconductor laser spot.

When the semiconductor laser device 202 according to the present invention as shown in FIG. 6 is used, the positioning allowance in the horizontal direction with respect to the substrate is larger than that of the conventional semiconductor laser having a circular spot size increase shown in FIG. Is 30% or more, the adjustment is simpler when mounting the semiconductor laser device 202, which is very advantageous.

In the present embodiment, a so-called TEC (Thermal Expansion Core) in which a part of the fiber as in the embodiment shown in FIG. 3 thermally expands the core at the end of the optical fiber in order to increase the positioning tolerance. You may use the optical fiber of a structure.

An example of a fiber having a TEC (Thermal Expansion Core) structure is shown in FIG. The fiber is obtained by expanding the core diameter by thermally diffusing the core of the single-mode fiber 301, and is expanded linearly (a linear function) as shown in FIGS. 3 (a) and 3 (c). As shown in FIGS. 3 (b) and 3 (d), there is a non-linearly expanded function (second or higher function).

In order to make the propagation loss in the core expansion region 302 close to 0, a linear expansion of the core expansion region 302 requires a long region, but a nonlinear expansion of the core expansion region 302. Requires a relatively short area.

By using the optical fiber having the above-mentioned TEC structure, the core diameter of the optical fiber can be increased, and as shown in FIG. 4, the positioning tolerance can be further increased to a value close to the core diameter of the fiber.

In this embodiment, a single mode optical fiber having an optical fiber core diameter of 10 μm is used. However, when the semiconductor laser spot diameter is 10 μm or less, the optical fiber core diameter is 10 μm or less. It may be an optical fiber.

As the above-mentioned substrate processing method, in the case of forming a V-shaped fiber alignment groove on a silicon substrate, KO having a very strong anisotropic selectivity with respect to the silicon substrate.
There is a method using an H-based etchant. With this method, the width and depth can be easily and accurately controlled simply by forming a mask on the silicon surface.

There is another method for dicing the silicon substrate by using a V-shaped processing blade. Also,
When processing a U-shaped or rectangular fiber centering groove, dicing cutting may be similarly performed using dedicated blades.

When the fiber alignment groove 204 has a rectangular shape, the fiber is supported on three sides as shown in FIG. 2, and the fiber is supported by two orthogonal corners formed between the substrate surface and the rectangular groove. There are two ways to do it.

When a silicon substrate is used as the substrate,
It is necessary to deposit an insulating film such as SiO2 in order to reduce the electric capacity. This increases the number of steps in manufacturing the optical coupling device. Therefore, it is also effective to use a quartz substrate, a glass substrate, a ceramic substrate, or the like, which is an insulator and is easy to process.

In particular, for a ceramic substrate, it is possible to produce a substrate with high precision simply by baking and hardening a ceramic material that has been die-cut from a die processed with high precision.

[0060]

As described above, by using the semiconductor laser element of the present invention as the semiconductor laser element of the optical coupling device, not only the coupling efficiency with the optical fiber which is the transmission line is dramatically improved. Another effect of this type of optical coupling device is the effect of increasing the positioning tolerance during mounting.

Further, by using various processed substrates for the optical coupling device, the device can be assembled very easily. Therefore, by implementing the present invention, it is possible to provide an optical coupling device that is inexpensive and highly reliable.

[Brief description of drawings]

1A is a cross-sectional view of a semiconductor laser according to a first embodiment of the present invention near a front end face thereof. FIG. 1B is a cross-sectional view of a semiconductor laser of a first embodiment according to the present invention near a rear end facet thereof. Top view of a semiconductor laser according to a first embodiment of the invention

FIG. 2A is a sectional view of an optical coupling device according to a second embodiment of the present invention. FIG. 2B is a top view of an optical coupling device according to a second embodiment of the present invention.

[FIG. 3] (a) Sectional view of a first embodiment of a TEC (Thermal Expansion Core) structured optical fiber (b) Sectional view of a second embodiment of a TEC (Thermal Expansion Core) structured optical fiber (c) TEC (Thermal Expansion Core) ) Cross-sectional view of the third embodiment of the structural optical fiber (d) TEC (Thermal Expansion Core) Cross-sectional view of the fourth embodiment of the structural optical fiber

FIG. 4 is a diagram showing a relationship between coupling efficiency and tolerance depending on a difference in spot diameter between a semiconductor laser and an optical waveguide calculated.

[Fig. 5] (a) Diagram of definition of spot diameter of semiconductor laser (b) Diagram of definition of spot diameter of optical fiber

FIG. 6 is a diagram showing the relationship between the positional deviation and the coupling efficiency of the present invention and the conventional semiconductor laser device with respect to the optical fiber by calculation.

FIG. 7 is a diagram showing a relationship between a stripe width W1 of a semiconductor laser and a spot diameter by a waveguide analysis.

FIG. 8 is a top view of a conventional WDM module.

FIG. 9 is a perspective view of a conventional semiconductor laser in which a spot is enlarged in a circle.

[Explanation of symbols]

101 n-type InP substrate 102 n-type InGaAsP optical confinement layer 103 multiple quantum well active layer 104 p-type InGaAsP optical confinement layer 105 p-type InP clad layer 106 p-type InP current blocking layer 107 n-type InP current blocking layer 108 p-type InP embedding Layer 109 p-type InGaAsP contact layer 110 Au / Sn electrode 111 SiO2 insulating film 112 Au / Zn electrode 113 Ti / Au electrode 114 Stripe 201 including active layer 201 Substrate 202 Semiconductor laser device in the present invention 203 Single-mode optical fiber 204 Fiber centering Groove 205 Core 206 Striped active layer 301 Single mode optical fiber 302 Core expansion region 303 Multimode optical fiber 304 Fiber fusion surface 501 Semiconductor laser 502 Semiconductor laser spot 503 Optical fiber core 504 Optical fiber spot diameter (core ) 801 substrate 802 optical fiber connected to a transmission line for transmitting bidirectional optical signals of wavelength 1.3 μm and 1.55 μm optical signal 803 wavelength 1.55 μm fiber for extracting optical signal 804 PLC (Planar Lightwave Circuit) optical circuit 805 wavelength Semiconductor light receiving element for detecting 1.3 μm optical signal 806 Lens 807 Semiconductor laser element 808 Mach-Zehnder type wavelength demultiplexer 809 Optical splitter 901 InP substrate 902 Stripe 903 InP buried layer 904 Multiple quantum well active layer 905 InGaAsP optical confinement layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Kitou 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (21)

[Claims] 1. A semiconductor laser, comprising a compound semiconductor substrate and a multilayer structure formed on the substrate, which emits laser light, the multilayer structure including at least an active layer,
The active layer is formed in a stripe shape in the cavity direction, and the stripe width of the active layer is the width W1 at the front end face.
And the width W2 at the rear end face are in the relationship of W1> W2, the stripe width continuously increases from W2 to W1 in the resonator direction, and the spot diameter is large in the horizontal direction with respect to the substrate. A semiconductor laser device capable of generating a laser beam. 2. The multi-layer structure includes an active layer and an optical confinement layer adjacent to the active layer, and an optical waveguide region including the active layer and the optical confinement layer is formed in a stripe shape in the cavity direction. The width of the stripe is W1> W2 between the width W1 at the front end face and the width W2 at the rear end face, and the stripe width is W2 to W1 in the resonator direction.
2. The semiconductor laser device according to claim 1, wherein a laser beam having a large spot diameter is generated in a horizontal direction with respect to the substrate. 3. The semiconductor laser device according to claim 1, which has a function of unifying transverse modes in the stripe of the semiconductor laser. 4. The semiconductor laser device according to claim 3, wherein the stripe structure of the semiconductor laser is partially narrowed. 5. The semiconductor laser device according to claim 4, wherein the semiconductor laser device has a structure in which the stripe width is tapered toward the front end face in the cavity direction of the semiconductor laser. 6. The semiconductor laser device according to claim 1, wherein both end faces or one of the front and rear end faces is highly reflectively coated to reduce the threshold current of the semiconductor laser. 7. A diffraction grating for periodically modulating an actual refractive index in the laser cavity direction is formed near the active layer, and oscillates at a single wavelength.
3. The semiconductor laser device according to item 1. 8. An optical waveguide and a laser light source are arranged so as to oppose each other so as to be optically coupled, and an optical signal emitted from the laser light source is sent to an optical fiber transmission line connected to the outside through the optical waveguide. Optical coupling device. 9. The optical coupling device according to claim 8, wherein a semiconductor laser element is used as the laser light source. 10. The optical coupling device according to claim 9, wherein the semiconductor laser device according to claim 1 is used as the semiconductor laser device. 11. The optical coupling device according to claim 10, wherein the stripe width on the front end face of the active layer of the semiconductor laser device is set to about the spot diameter of the optical waveguide. 12. The optical coupling device according to claim 11, wherein the optical waveguide and the semiconductor laser device are formed on the main surface of the substrate. 13. The optical coupling device according to claim 12, wherein the optical waveguide is formed by disposing a part of an optical fiber on the main surface of the substrate. 14. A so-called TEC (Thermal) in which a part of the optical fiber is a thermally expanded core at the end of the optical fiber.
The optical coupling device according to claim 13, which is an optical fiber having an Expansion Core structure. 15. The optical coupling device according to claim 13, wherein a groove for aligning the optical fiber is formed on the substrate. 16. The silicon substrate on which an insulating film is deposited is used as the substrate.
The optical coupling device according to item 1. 17. The optical coupling device according to claim 15, wherein a quartz substrate is used as the substrate. 18. The optical coupling device according to claim 15, wherein a glass substrate is used as the substrate. 19. The optical coupling device according to claim 15, wherein a ceramic substrate is used as the substrate. 20. The V-shaped groove is formed by selectively etching the fiber alignment groove of the silicon substrate with a KOH-based etchant.
7. A method for manufacturing the optical coupling device according to. 21. A rectangular, V-shaped or U-shaped groove formed by cutting a fiber centering groove of the silicon substrate, quartz substrate, glass substrate or ceramic substrate with a dicing saw.
19. Formed into a shape.
Or the method for manufacturing an optical coupling device described in 19.