KR101764342B1

KR101764342B1 - Wavelength-swept light source for optical communication

Info

Publication number: KR101764342B1
Application number: KR1020150152001A
Authority: KR
Inventors: 조호성
Original assignee: (주)엘디스; 조호성
Priority date: 2015-10-30
Filing date: 2015-10-30
Publication date: 2017-08-14
Also published as: KR20170050458A

Abstract

The semiconductor optical amplifier 40 has a cubic body with one side constituting an output terminal and the other side opposite to the opposite side constituting a reflection terminal. The wedge-shaped groove 45 is formed in the body of the optical amplifier 40 so as to face inward from the front edge of the body. So that the inclined surfaces 48a and 48b are formed to have a first inlet on the upper surface of the body and a second inlet on the front surface of the body, and both sides of the inlet of the second inlet are narrowed toward the inside, 48b are formed, and inner side surfaces 46, 47 are formed so as to be parallel to each other on both inner side surfaces extending inward from the inclined surfaces 48a, 48b. The bar active regions 41 and 42 are formed on both sides of the wedge-shaped groove 45, respectively. The bar size active areas 41 and 42 are positioned such that the area of contact with both inner end faces 46 and 47 is less than the width of the inner light path P between the inner end faces 46 and 47, And the vertical axis of the Fabry-Perot filter 33 is inclined relative to the inner light path P.

Description

Wavelength-swept light source for optical communication [

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength tunable light source for optical communication, and more particularly, to a variable wavelength light source for optical communication in which a wavelength tunable filter to which a microelectronic mechanical system (MEMS) is applied is built in an optical amplifier.

A semiconductor laser which oscillates at a single wavelength has been used as a light source for optical communication. Recently, wavelength division multi-flexing (WDM) optical communication systems have been expanding their transmission capacity by using a plurality of semiconductor lasers arranged at narrow wavelength intervals and operating at different wavelengths. For example, when 40 semiconductor lasers having oscillation wavelengths of 0.8 nm intervals in the wavelength band of 1530 to 1565 nm are used at the same time, a transmission capacity enlargement of 40 times or more can be obtained compared to when using one laser.

However, in order to construct a WDM optical communication system, different types of semiconductor lasers corresponding to the number of wavelengths to be used must be prepared.

The variable wavelength light source for optical communication is a semiconductor laser having a characteristic capable of variably controlling the oscillation wavelength, and is economical because it can cope with various wavelengths necessary for constructing a WDM optical communication system as a single wavelength variable light source. The wavelength tunable light source for optical communication can be divided into a semiconductor laser internal resonator type and an external resonator type according to a wavelength variable method.

The internal resonator type is disadvantageous in that it is difficult to manufacture due to the complexity of the wavelength selecting mechanism, and continuous wavelength tuning is difficult because wavelength control by current injection also has nonlinear characteristics.

The external resonator type is advantageous in that the wavelength can be changed linearly and continuously by adjusting the diffraction wavelength of the diffraction grating in such a manner that a laser resonator is formed by a semiconductor optical amplifier and a diffraction grating which is an external wavelength selection element. In recent years, MEMS technology is applied to fine angle adjustment of a diffraction grating to produce a wavelength tunable light source capable of precise wavelength adjustment.

However, in the conventional wavelength tunable light source for external resonator type optical communication employing MEMS technology, a three-dimensionally aligned lens must be inserted in order to minimize the optical loss of the external resonator portion including the semiconductor optical amplifier and the diffraction grating, And has a disadvantage of lengthening. That is, since an external resonator is formed of a bulk optical component of a lens and a diffraction grating, the lens alignment is costly and the size of the resonator is so large that it is difficult to miniaturize and integrate the light source, It is.

FIG. 1 is a view for explaining a conventional external resonator type wavelength tunable light source to which the MEMS technology is applied. 1, a conventional external resonator type tunable light source includes a semiconductor optical amplifier 10, a parallel light lens 16, and a diffraction grating 17.

The semiconductor optical amplifier 10 comprises a p-electrode 13, an n-electrode 14 and a rod active region 12. The diffraction grating 17 is supported by the MEMS driver 18, Lt; / RTI >

Light generated in the active region 12 passes through the anti-reflection film 15, is converted into parallel light through the lens 16, and is incident on the diffraction grating 17. The diffraction grating 17 provides a reverse path in which only one wavelength of light that satisfies the diffraction condition re-enters the active region 12 through the lens 16. [

The resonator of the conventional variable wavelength light source is formed between the output face 11 and the diffraction grating 17 and the diffraction grating 17 is formed between the output face 11 and the diffraction grating 17 since a portion of the output light is output from the output face 11 of the semiconductor optical amplifier 10, Only the optical wavelength (optical mode) selected by the laser oscillator satisfies the resonance condition and is laser oscillated. At this time, when the voltage is applied to the MEMS driver 18 to adjust the angle 19 of the diffraction grating 17, the wavelength of the optical output can be varied.

However, as described above, the external resonant wavelength tunable light source has a disadvantage in that it requires accurate three-dimensional optical alignment of the parallel light lens 16 and the diffraction grating 17, and the resonator length becomes long due to its large volume.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-described problems of the related art by providing a wavelength tunable characteristic that is simple in structure and simple in structure by applying MEMS technology, It is an object of the present invention to provide a new type of variable wavelength light source for optical communication, which has both advantages of resonator type and external resonator type which has advantages of linear and continuous wavelength tunability.

According to an aspect of the present invention, there is provided a variable wavelength light source for optical communication,

A silicon MEMS substrate on which a Fabry-Perot filter is formed, and a semiconductor optical amplifier,

The semiconductor optical amplifier includes:

A cuboid body having an output end on one side and an opposite side on the other side;

The body having a first inlet formed on an upper surface side of the body and a second inlet formed on a front surface side of the body so as to have a predetermined depth on an upper surface of the body so as to face inward from a front edge of the body, A wedge-shaped groove formed on both side surfaces thereof to form an inclined surface so as to become narrower toward the inside, and inner side surfaces formed to be parallel to each other on both inner side surfaces extending further inward from the inclined surface; And

A rod-shaped active region formed on both sides of the wedge-shaped groove; , &Lt; / RTI >

The upper surface of the body is flip-chip bonded to the silicon MEMS substrate,

The Fabry-Perot filter is installed to be inserted into the wedge-shaped groove through the second inlet so as to be inclined with respect to the inner end face,

Wherein the rod-shaped active area is formed such that the areas of contact with both inner end faces are offset from each other such that the inner optical path between the inner end faces is longer than the width between the inner end faces, And the vertical axis of the filter is inclined.

It is preferable that a filter driving unit is further provided on the silicon MEMS substrate to control the thickness of the spacer of the Fabry-Perot filter in order to vary the transmission wavelength for the Fabry-Perot filter. In this case, it is preferable that the Fabry-Perot filter and the filter driving unit are formed by MEMS (Micro Electro Mechanical System) technology.

Preferably, the bar active region has a tapered portion in the vicinity of the inner end face, and the tapered portion is formed so as to be widened toward the inner end face while being bent or inclined so as not to be perpendicular to the inner end face.

The tapered portions are preferably formed symmetrically opposite to each other in the bar-like active region formed on both sides of the wedge-shaped groove.

Preferably, an alignment guide is formed on the silicon MEMS substrate by a MEMS technique to position the semiconductor optical amplifier so that the semiconductor optical amplifier can be flip-chip bonded to the silicon MEMS substrate in situ, Wherein the filter driving unit includes a movable comb, a movable electrode, a fixed comb, and a fixed electrode, wherein the movable comb, the movable comb, the fixed comb, and the fixed electrode, Wherein an extended arm of the alignment guide and an extended arm of the movable comb form the Fabry-Perot filter, and a distance between the movable comb and the fixed comb is varied by an applied voltage between the movable electrode and the fixed electrode, Wherein the movable comb and the stationary comb are connected to each other by an extension arm of the movable comb It is preferable that the distance between the extension arms of the alignment guide, a variable group.

By forming the slit layer by removing the silicon portion from the extending arm of the alignment guide and the extending arm of the movable comb, alternately arranging the silicon having the high refractive index and the air layer having the small refractive index on the extending arms, .

And the inclined surface of the second inlet is formed to be inclined at an angle not perpendicular to the internal optical path.

The variable wavelength light source for optical communication according to the present invention not only has a simple structure to which the MEMS technology is applied, but also has a wavelength variable characteristic proportional to an adjustment signal. In other words, it has both advantages of internal resonator type with advantages of integration and high speed modulation possibility and external resonator type with linear and continuous wavelength tunability advantages.

1 is a view for explaining a conventional external resonator type wavelength tunable light source to which MEMS technology is applied;
2 to 4 are views for explaining a wavelength variable light source for optical communication according to the present invention;
5 is a diagram for determining a laser oscillation wavelength for a wavelength variable light source for optical communication according to the present invention;
FIGS. 6 and 7 are diagrams for explaining an example of the semiconductor optical amplifier 40 used in the wavelength variable light source for optical communication according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are merely provided to understand the contents of the present invention, and those skilled in the art will be able to make many modifications within the technical scope of the present invention. Therefore, the scope of the present invention should not be construed as being limited to these embodiments.

2 to 4 are diagrams for explaining a variable wavelength light source for optical communication according to the present invention, FIG. 2 is a plan view as a whole, FIG. 3 is a perspective view for explaining a semiconductor optical amplifier 40 of FIG. 1, 1 is an enlarged view of a portion A in FIG. 1 to explain the Fabry-Perot filter 33. FIG.

2 to 4, the variable wavelength light source for optical communication according to the present invention includes a silicon MEMS substrate 20 and a semiconductor optical amplifier 40.

The semiconductor optical amplifier 40 has a cubic body as shown in FIG. 3, a p-electrode is formed on the upper surface of the body, and an n-electrode is formed on the lower surface. When the semiconductor optical amplifier 40 is assembled to the silicon MEMS substrate 20, flip chip bonding is performed on the silicon MEMS substrate 20 such that the upper surface with the p-electrode is downward.

The semiconductor optical amplifier 40 has one side of the cubic body as an output terminal and the other side opposite to the other side as a reflection terminal. The anti-reflection film 43 is formed on one side of the output terminal, A high reflective film 44 is formed on the other side surface to be formed. The anti-reflection film 43 and the high reflection film 44 are formed to be parallel to each other.

In the semiconductor optical amplifier 40, a wedge-shaped groove 45 is formed at one corner of the cubic body at a depth of about 15 mu m on the upper surface so as to face inward from the front edge. Accordingly, the first inlet of the wedge-shaped groove 45 is formed on the upper surface side of the cubic body, and the second inlet of the wedge-shaped groove 45 is formed on the front surface side of the cubic body. The wedge-shaped groove 45 is for inserting the Fabry-Perot filter 33.

The second inlet of the wedge-shaped groove 45 is formed with inclined surfaces 48a and 48b narrowed inwardly on both side surfaces of the inlet side and on both inner side surfaces extending inwardly from the inclined surfaces 48a and 48b, The inner end faces 46 and 47 are formed. The inner end faces 46 and 47 are formed parallel to the anti-reflection film 43 and the high reflection film 44, and the inclined faces 48a and 48b have a shape extending outward at a predetermined angle, for example, about 18 degrees.

On both sides of the wedge-shaped groove 45, the rod-like active regions 41 and 42 are formed at a depth of 3 to 5 탆 from the upper surface on which the p-electrode is located. Reference numeral 41 denotes a rod-shaped active region formed between the inner end face 46 and the anti-reflection film 43, 42 denotes a rod-shaped active region formed between the inner end face 47 and the high- Lt; / RTI >

Although not shown in the figure, it is preferable to have a general planar buried heterostructure (PBH) structure in which the current blocking layers are disposed on both sides of the width direction of the rod active regions 41 and 42 so that current is injected only into the active region.

The two rod active areas 41 and 42 are not located at the same position but are shifted from each other such that the areas where the inner end faces 46 and 47 meet are opposite to each other. As a result, the optical internal light path P becomes longer than the interval between the inner end faces 46, 47. An internal light path P inclined by about 24 degrees with respect to the vertical axis of the internal end faces 46 and 47 will be formed between the internal end faces 46 and 47. In this case, P will be about 35 / cos24 DEG = 83 mu m when the interval between the inner end faces 46, 47 is 35 mu m.

The active area 41 is curved at an angle of about 7 degrees so as not to be vertical when the inner end face 46 meets the inner end face 46 and has a length of 100 to 300 占 퐉 Of the tapered portion T. The same applies to the case of the rod active region denoted by reference numeral 42. The tapered portions T in the two bar active areas 41 and 42 are preferably symmetrically arranged so as to be opposite to each other as shown.

The reason for tapering the taper T about 7 degrees relative to the vertical axis of the inner end faces 46 and 47 is that the light reflected at the inner end faces 46 and 47 returns to the bar size active areas 41 and 42, The width of the bar size active areas 41 and 42 is increased toward the inner end faces 46 and 47 so as to form a curved bar large active area at the portion where the inner end faces 46 and 47 meet, The reason for increasing the spot size of the light guide plates 41 and 42 is to minimize the divergence loss of light due to the long internal light path P being formed.

The semiconductor optical amplifier 40 performs a modulation function of the optical output according to the provision of the optical gain by the rod-like active regions 41 and 42, the role of forming the resonator, and the injection current modulation.

A Fabry-Perot filter 33, a filter drive actuator, alignment guides 26 and 28, and electrode lead-out pads 31 and 32 are formed on the silicon MEMS substrate 20.

The alignment guides 26 and 28 serve to position the semiconductor optical amplifier 40 so that it can be flip-chip bonded in place. The semiconductor optical amplifier 40 is mounted on the silicon MEMS substrate 20 while the extension arm 27 of the alignment guide 26 and the extension 29 of the alignment guide 28 are in close contact with the two inclined surfaces 48a and 48b, Flip chip bonding.

The extension arm 27 of the alignment guide 26 and the extension arm 23 of the movable comb 21 are inclined by about 18 degrees with respect to the inner end faces 46 and 47. [ That is, the inner light path P is inclined by 24-18 = 6 ° with respect to the vertical axis of the Fabry-Perot filter 33.

The reason why the internal light path P has an inclination angle that is inclined with respect to the Fabry-Perot filter 33 is that the reflected light of the entire wavelength except the transmission wavelength of the Fabry-Perot filter 33 is reflected by the bar size active areas 41 and 42 In order to prevent it from returning to the original state.

The filter driving unit for driving the Fabry-Perot filter 33 includes a movable comb 21, a movable electrode 22, a fixed comb 24, and a fixed electrode 25.

The Fabry-Perot filter 33 and the filter driving unit form a 1 to 2 탆 thick silicon oxide layer and a 10 탆 thick silicon layer on the silicon MEMS substrate 20, And is formed by MEMS technology by removing the silicon oxide film to levitate the molded part.

The Fabry-Perot filter 33 is formed by forming a slit layer 30 having a refractive index lower than that of silicon at the end of the extending arm 27 of the alignment guide 26 and the end of the extending arm 23 of the movable comb 21, . The slit layer 30 may be formed by various methods such as forming a doping layer on the silicon constituting the extending arms 23 and 27 or removing a part of silicon to form an air layer. The latter case will be described below.

A silicon layer (high refractive index layer) having a refractive index of 3.4 and an air layer (low refractive index layer) having a refractive index of 1 are formed at the end of the extending arm 27 of the alignment guide 26 and at the end of the extending arm 23 of the movable comb 21, (The thickness of the spacer) of the reflectors is set so that only the light wavelength that is multiples of the spacing between the reflectors (spacer thickness) is selectively applied to the Fabry-Perot And passes through the filter 33.

In the drawing, three silicon layers and two air layers are alternately arranged to form respective reflectors. It is preferable that the high refractive index layer and the low refractive index layer in each reflector have an optical thickness corresponding to an odd integer multiple of the thickness corresponding to 1/4 of the wavelength used.

For example, the thickness of the silicon layer is 2.4 times as thick as 1/4 wavelength of 1550 nm as a center wavelength of 1550 nm, the air layer is 5 times as thick as 1.9 占 퐉, and the spacer, which is a gap between the reflectors, And the initial thickness of the spacer is set to 2.25 탆, which is three times the ½ wavelength, based on the transmission wavelength of 1500 nm.

When a voltage is applied between the movable electrode 22 and the fixed electrode 25, an electric attraction force acts between the movable comb 21 and the fixed comb 24 to move the movable comb 21 toward the fixed comb 24 Which increases the spacer thickness (spacing between reflectors) of the Fabry-Perot filter 33.

When the thickness of the spacer is 2.25 탆, the transmission wavelength of the Fabry-Perot filter 33 is 1500 nm, and when the thickness of the spacer is 2.4 탆, the transmission wavelength of the Fabry-Perot filter 33 is 1600 nm. When the thickness of the spacer is varied between 2.25 탆 and 2.4 탆 by controlling the applied voltage, it is possible to continuously vary the transmission wavelength in the range of 1500 to 1600 nm.

The same wavelength tuning characteristics can be obtained even when the movable comb 21 and the fixed comb 24 are disposed opposite to each other and the initial value of the spacer thickness is set to 2.4 m and the voltage is varied to 2.25 m according to the voltage application. Lt; / RTI >

When the wavelength tuning range is set to 1530 to 1565 nm, the corresponding voltage range is measured and stored in the memory, and the voltage corresponding to the desired wavelength is called up to operate.

5 is a laser oscillation wavelength determination diagram for a wavelength variable light source for optical communication according to the present invention. The inner light path P and the Fabry-Perot 33 filter are disposed at an angle of about 6 degrees with respect to each other because the Fabry-Perot filter 33 is inclined by about 18 degrees and the inner light path P is inclined by about 24 degrees. Tilted. As a result, the reflected light generated at each of the boundary surfaces 46, 47, 27, and 23 can not be returned to the rod-shaped active regions 41 and 42, thereby eliminating formation of a local resonator.

Therefore, the resonator of the present invention has an internal light path (not shown) of the wedge-shaped groove 45 including the rod-shaped active areas 41 and 42 between the anti-reflection film 43 and the high reflection film 44 and the Fabry- P) and forms a resonator mode (Fabry-Perot mode) shown in FIG.

The wavelength interval between the resonator modes when the total length of the semiconductor optical amplifier 40 is about 800 mu m is about 0.4 nm. When the transmission wavelength of the Fabry-Perot filter 33 is determined by the humanized voltage between the movable electrode 22 and the fixed electrode 25, the resonator mode closest to the vertex of the transmission wavelength curve has the minimum transmission loss The single-wavelength laser oscillation is performed by reciprocating the resonator. Since the resonator mode deviating from the vertex of the transmission curve is reflected by the Fabry-Perot filter 33, the resonator can not be reciprocated, and laser oscillation is suppressed.

When the transmission wavelength curve of the Fabry-Perot filter 33 is continuously moved by changing the applied voltage, the adjacent resonator modes are sequentially selected and oscillated in a form of oscillation. In the case of a resonator having a length of 800 탆, the oscillation wavelength is shifted at an interval of about 0.4 nm, so that the wavelength of the selected oscillation mode must be continuously varied by ± 0.2 nm in order to obtain a continuous wavelength tuning characteristic.

Continuous wavelength tuning of ± 0.2 nm can be achieved by varying the current injection to the curved rod-like active regions 41 and 42 by changing the effective refractive index of the resonator while keeping the laser light power constant. In order to increase the efficiency of the micro continuous wave length modulation of ± 0.2 nm, the length ratio of the rod-shaped active regions 41 and 42 can be asymmetrically set to 1: 1 symmetry such as 3: 1.

6 is a view for explaining an example of a semiconductor optical amplifier 40 used in a wavelength variable light source according to the present invention. 6A is a plan view of the semiconductor optical amplifier 40 viewed from the top side, and the rod active regions 41 and 42 are formed so as to be embedded as indicated by the dotted lines. 6B shows a state in which an electrode is formed in FIG. 6A, and p-electrodes 51 and 52 and p-electrode pads 49 and 50 are formed on the upper surface of the rod active regions 41 and 42, respectively.

7 is a view for explaining another example of the semiconductor optical amplifier 40 used in the wavelength variable light source according to the present invention. 7A shows a mode in which a new active region 53 is added to the active region 41 via a Y-type branch region. The added active region 53 serves to amplify the laser oscillation light whose wavelength has been varied by the rod-shaped active regions 41 and 42 and the Fabry-Perot filter 33, whereby some laser oscillation light in the Y- The light is amplified by branching to the region 53 and going back and forth.

7B shows a state in which an electrode is formed in FIG. 7A. The p-electrode and the p-electrode pad 49, 50 and 54 are formed on the upper surface of the active region 41 and 42, respectively. The reason why the three p-electrodes and p-electrode pads are arranged so as to be insulated from each other is that the laser oscillation mode selected in the tunable resonator satisfies the resonance condition in the optical amplification resonator, To adjust the length of the resonator.

The wavelength tunable light source of the present invention obtains optical output modulation by modulating the current applied to one or more p-electrodes. In order to increase the modulation speed, in the case of the PBH structure cited in the description of the present invention, Two channels each having a depth of about 20 占 퐉 and a depth of about 10 占 퐉 are formed at intervals of about 30 占 퐉 m to reduce the parasitic static charge component. This is the same as the method for improving the modulation speed of a laser of a general PBH structure, The description will be omitted.

In addition, if the cross-sectional structure of the resonator including the active region instead of the PBH structure is adopted as RWG (ridge waveguide) type having a width of 2 to 3 탆 and a depth of 5 to 10 탆, fast modulation performance can be obtained by reducing parasitic capacitance. Since the structure is the same as that of a general RWG laser, a detailed description thereof will be omitted.

10, 40: semiconductor optical amplifier 11: output face
12, 41, 42, 53: a bar active region 13, 51, 52: a p-electrode
14: n-electrode 15, 43:
16: Lens for parallel light 17: Diffraction grating
18: MEMS driver 20: Silicon MEMS substrate
21: movable comb 22: movable electrode
23, 27: extension arm 24: stationary comb
25: fixed electrode 26, 28: alignment guide
29: extension part 30: slit layer
31, 32: Electrode withdrawal pad 33: Fabry-Perot filter
44: high reflective film 45: wedge-
46, 47: internal section 48a, 48b: inclined surface
49, 50, 54: p-electrode pad P: optical internal light path
T: Taper portion

Claims

A silicon MEMS substrate on which a Fabry-Perot filter is formed, and a semiconductor optical amplifier,
The semiconductor optical amplifier includes:
A cuboid body having an output end on one side and an opposite side on the other side;
The body having a first inlet formed on an upper surface side of the body and a second inlet formed on a front surface side of the body so as to have a predetermined depth on an upper surface of the body so as to face inward from a front edge of the body, A wedge-shaped groove formed on both side surfaces thereof to form an inclined surface so as to become narrower toward the inside, and inner side surfaces formed to be parallel to each other on both inner side surfaces extending further inward from the inclined surface; And
A rod-shaped active region formed on both sides of the wedge-shaped groove; , &Lt; / RTI >
The upper surface of the body is flip-chip bonded to the silicon MEMS substrate,
The Fabry-Perot filter is installed to be inserted into the wedge-shaped groove through the second inlet so as to be inclined with respect to the inner end face,
Wherein the rod-shaped active area is formed such that the areas of contact with both inner end faces are offset from each other such that the inner optical path between the inner end faces is longer than the width between the inner end faces, And the vertical axis of the filter is inclined.

The filter according to claim 1, further comprising a filter driver installed on the silicon MEMS substrate to control the spacer thickness of the Fabry-Perot filter to vary the transmission wavelength for the Fabry-Perot filter, And the driving unit is formed by EMS (Micro Electro Mechanical System) technology.

[2] The apparatus of claim 1, wherein the bar active region has a tapered portion in the vicinity of the inner end face, and the tapered portion is formed so as to be widened toward the inner end face while being bent or inclined so as not to be perpendicular to the inner end face A variable wavelength light source for optical communication.

4. The variable wavelength light source for optical communication according to claim 3, wherein the tapered portions are symmetrically formed so as to be opposite to each other in a rod-like active region formed on both sides of the wedge-shaped groove.

The semiconductor optical amplifier according to claim 2, wherein an alignment guide for positioning the semiconductor optical amplifier so that the semiconductor optical amplifier can be flip-chip bonded to the silicon MEMS substrate in place is formed on the silicon MEMS substrate by MEMS technology,
Wherein the alignment guide includes an extension arm provided so as to be in contact with one of the slopes of the second inlet, and an extension provided so as to be in contact with the other slope,
The filter driving unit includes a movable comb, a movable electrode, a fixed comb, and a fixed electrode,
An extension arm of the alignment guide and an extension arm of the movable comb form the Fabry-Perot filter,
Wherein a distance between the movable comb tooth and the fixed comb tooth is varied by an applied voltage between the movable electrode and the fixed electrode, and the distance between the extended arm of the movable comb and the stationary comb tooth And the distance between the extending arms of the alignment guide is variable.

6. The method of claim 5, wherein a silicon portion is removed from the extension arm of the alignment guide and the extension arm of the movable comb to form a slit layer so that silicon having a large refractive index and air layer having a small refractive index are alternately arranged on each of the extension arms, And a Fabry-Perot filter is formed.

6. The variable wavelength light source for optical communication according to claim 5, wherein the inclined surface of the second inlet is inclined at an angle not perpendicular to the inner optical path.