JPH06283802A - Semiconductor laser device and fabrication thereof - Google Patents

Abstract

PURPOSE:To realize a semiconductor laser emitting laser light of a plurality of wavelengths from one emitting face by growing a plurality of types of crystal in the direction of cavity and forming a diffraction grating corresponding thereto. CONSTITUTION:An oxide or a nitride is patterned on an n-type InP(100) on which a diffraction grating 2 is formed and then it is subjected to dry etching to form a ridge 4 and a groove 5 in the unflat groove width modulation type substrate in the direction <011> with the width (dw) and the height (h) of the ridge being set at 1.5mum and 2mum. The width (dg) increases from 1.5mum to 3.0mum, 3.5mum, 4.0mum and 10.0mum for every 300mum length of the ridge thus forming an optical waveguide layer of InGaAsP, a light emission layer 6 having a distorted quantum well structure comprising a barrier of InGaP well of 30Angstrom / InGaAsP of 150Angstrom , and a P-InP clad layer 7. This constitution realizes a laser light source integrated at high density while having a wide emission characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device used as an integrated light source in a wavelength division multiplexing or optical frequency division multiplexing optical communication system (WDM or FDM) and a manufacturing method thereof, for optical communication and optical information processing. It is also used as a wavelength tunable light source or a wavelength conversion element which is a basic optical device of. In addition, a semiconductor distributed reflector for use in a semiconductor laser with a wavelength sweep function suitable as a light source for transmission and a tunable light source for synchronous detection in an optical wavelength (frequency) multiplex communication system in the optical communication field, and a light source for optical measurement. It can also be applied as a manufacturing method.

[0002]

2. Description of the Related Art An array type has been generally considered as a multi-wavelength laser until now. For example, there is a method of changing the oscillation wavelength of a wafer having a crystal structure of uniform composition by changing the period of the diffraction grating (Journal of the Institute of Electronics, Information and Communication Engineers, J73-C-1, Volume 5, No. 5, p. .2
91 (1990), Nakao et al.). However, in this method, the wavelength range in which the laser can oscillate is determined by the so-called gain width, and therefore the amount of change in wavelength is at most about 100 nm, and the oscillation characteristics of the laser also change depending on the wavelength range.

There is also a method of changing the oscillation wavelength according to the temperature by utilizing the temperature characteristic of the semiconductor band gap, but this has a slow response, is not suitable for integration, and changes other laser characteristics. There are drawbacks such as being lost.
Also, as a semiconductor laser capable of sweeping a wavelength over a wide range, a distributed bragg reflecter laser
r: DBR laser) has been developed, but there are drawbacks such that the wavelength sweep width is limited by the gain width as described above, and a plurality of laser beams cannot be emitted at the same time.

For the conventional increase in the amount of communication information, research has been conducted on an optical wavelength (frequency) multiplex communication system.
A wide range of wavelength sweeping function is required as a transmission light source and a synchronous detection tunable light source, and also in the field of optical measurement, realization of a variable wavelength light source covering a wide wavelength band is desired.

As a variable wavelength light source, a number of distributed reflection type semiconductor lasers, which can easily sweep the wavelength by injecting current, have been studied. Since the diffraction grating pitch in these distributed reflector regions is uniform, λ = 2Λn _eq (Λ:
The oscillation wavelength near the black wavelength λ, which is determined by the pitch of the diffraction grating, n _eq : equivalent refractive index), is determined by the electrical equivalent refractive index change Δn _eq of the equivalent refractive index n _eq of the inactive waveguide region. Therefore, since the maximum refractive index change Δn / n of the semiconductor due to the normal current injection is about 1%, the wavelength sweep width of the distributed reflection type semiconductor laser of the above-mentioned conventional example stays at about 100 Å, and the light source for the optical wavelength division multiplexing communication system. As a result, there was a problem of being insufficient.

On the other hand, in an optical waveguide including one or more optical waveguide layers having a refractive index larger than that of the semiconductor substrate formed on the semiconductor substrate, the pitch of the diffraction grating formed on the optical waveguide is Λ _a. From Λ _b to a region that changes continuously or intermittently has a period M _f (where M _f >
From the wavelength λ _a = 2Λ _a n _eq to the wavelength λ _b = 2Λ, the reflection characteristics of the semiconductor distributed reflector repeatedly formed by Λ _a , Λ _b ).
Wavelength interval Δλ _f = λ ₀ ² / 2n _eq M up to _b n _eq
By taking the characteristic that the reflection peaks are periodically obtained at _f (λ ₀ = n _eq (Λ _a + Λ _b )), the wavelength tunable laser having the reflecting mirror can obtain a wavelength tunable range that is one digit larger than the conventional one. (Japanese Patent Application No. 4-222718).

As a structure having the same effect as the above diffraction grating, a medium having different refractive indexes is formed on a uniform diffraction grating to obtain a reflector having a plurality of high reflectance peaks. A wavelength tunable laser having the above has been proposed (Japanese Patent Application No. 4-213084).

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and utilizes crystal growth on a non-flat substrate to have a broad band emission characteristic and a high density integration. The main purpose is to realize a laser light source that emits light from the same emission surface. Another object of the present invention is to provide a manufacturing method for producing a semiconductor waveguide having different refractive index changes by a single crystal growth.

[0009]

The structure of the semiconductor laser device of the present invention which solves the above-mentioned problems is such that the width of a ridge formed in advance on a semiconductor, the distance between adjacent ridges (groove width), and the height of the ridge are set. A semiconductor multilayer film having a strained multiple quantum well (MQW) structure is formed as an active layer by a metal organic vapor phase epitaxy (MOVPE) method within a predetermined range, and a light guide layer is provided on the ridge as needed. It is characterized by

The structure according to the method of manufacturing a semiconductor laser device of the present invention, which solves the above problems, has two grooves formed on a semiconductor substrate on which a diffraction grating having a uniform pitch Λ ₀ and a uniform depth is formed. The width of the encircled area is constant, both groove widths or groove depths are symmetrical with respect to the groove direction, and the groove widths or groove depths are continuous or intermittent with respect to the groove direction. Of the groove width or the depth of the groove is formed in a region sandwiched by two grooves by forming a region in which the width changes to a cycle with a large period Λ _s and crystal-growing a quantum well waveguide structure on the region. Of the waveguide layers having different bandgap compositions in different regions of the
A quantum well waveguide layer in which a region that continuously or intermittently changes from _a to n _b is repeated with the period Λ _a is grown, and at least λ _a (= 2
The present invention is characterized in that a distributed reflector having one or more reflectance peaks is formed from n _a Λ ₀ ) to λ _b (= 2n _b Λ ₀ ). Alternatively, the diffraction grating having the uniform pitch Λ ₀ and the uniform depth is formed not on the semiconductor substrate but on the quantum well waveguide.

[0011]

MOVPE is formed on a semiconductor substrate having a pattern in which the ridge width, the groove width, and the ridge height are preset.
When a semiconductor multi-layer film having a strained quantum well structure is formed by the method, a difference in the moving speed of semiconductor constituent elements depending on the crystal plane is caused due to the characteristic of crystal growth, and the composition of the n-strained multiple quantum well film on the ridge is slightly different. While making changes. Therefore, an optical functional element having a slightly different thickness and composition of the active layer can be formed on the plurality of ridges, and its wavelength characteristic can be controlled in a wide range.

In controlling the wavelength characteristics, the main cause of the change is the change in the composition of the quantum well layer. FIG. 1 shows that the tensile strain formed on the ridge-shaped substrate is 0.5.
% Well layer with a thickness of 17 Å In _1-x Ga _x As / InGa
It shows the shift amount of the emission wavelength of the quantum well layer made of AsP (λg = 1.1 μm). After the strained quantum well layer similar to that of the present invention was crystal-grown on a flat substrate, a predetermined active layer width was formed by dry etching, and the light emitting element filled with the semiconductor thin film layer again had an emission wavelength of 1. 27μ
m.

FIG. 1A shows the relationship between the height h of the ridge and the constant amount of 2 μm, and the variation of the emission wavelength when the ridge width dw is changed from 1 μm to 6 μm.
The characteristic is shown with g as a parameter. As can be seen from the figure, when the groove width dg is 3 μm or less, the ridge width dw
On the other hand, the shift amount of the emission wavelength is remarkably increased. When the ridge width dw is 4 μm or more, the shift amount of the emission wavelength is extremely small.

In FIG. 1B, the ridge width dw is used as a parameter for the relationship with the amount of change in the emission wavelength when the groove width dg is changed from 1 μm to 10 μm with the height h of the ridge being constant at 2 μm. It shows the characteristics of the above. As can be seen from the figure, when the ridge width dw is 2 μm or less, the shift amount of the emission wavelength changes significantly with respect to the change of the groove width dg, and particularly when the groove width dg is 6 μm or less.

In FIG. 1C, the height h of the ridge is 1.2 μm to 2.2 μm with the groove width dg being constant at 1.5 μm.
It shows the characteristics with the ridge width dw as a parameter with respect to the relationship with the amount of change in the emission wavelength when it is changed to. It can be seen that the shift amount of the emission wavelength is remarkable with respect to the height h of the ridge. That is, from the characteristics of FIG. 2, when the ridge width dw, the height h, and the groove width dg are small dimensions of 10 μm or less, the amount of change in the emission wavelength is extremely large, and the emission wavelength can be controlled by a processing technique such as a ridge. Is shown. Further, the emission characteristics shift to the longer wavelength side as the ridge width dw is narrower and the groove width dg is narrower. The emission wavelength according to the prior art utilizing the growth on a flat plate is 1.27 μm, and the maximum emission wavelength according to the present invention is 1.27 μm.
A maximum shift amount of 6 μm of 300 nm can be realized.

When a crystal is grown on a certain narrow crystal surface, the crystal growth rate and crystal composition differ depending on the shape, surface state, or surface material of the region which is in contact with a part or all of the crystal plane. In particular, when a quantum well structure is formed on the crystal surface, a difference in the growth rate causes a difference in the well width of the quantum well, which has the effect of significantly changing the apparent composition. For example, as shown in FIG. 7C, the growth film thickness and composition of the bulk crystal grown in the region sandwiched by the SiO ₂ insulating films shown in FIG. 7A are as shown in FIG. 7C. ), And when the quantum well waveguide is grown as shown in FIG. 7D, it changes depending on the width of the insulating film (mask width Wm), and the oscillation wavelength shifts (1991 IEICE). National Convention C-131, Sasaki, etc.).

Therefore, as shown in FIGS. 8A and 8B, an insulating film mask 16 formed on the diffraction grating 15 formed with a uniform pitch Λ ₀ is used, and a quantum well structure is formed in the middle thereof. When selectively grown, the crystal composition of the central region can be changed by the shape of the insulating film mask 16 due to the effect shown in FIG. The equivalent effect is shown in FIG.
The structure shown in FIG. 3C, in which two grooves 17 are formed in the semiconductor, is also obtained, and the groove width dg or the groove depth (ridge height h on both sides of the crystal plane left in the ridge 18 between the two grooves 17 is obtained. )
Can also change the composition of crystals.

In this way, the diffraction grating has a uniform pitch Λ.
_The region in which the valve gap composition of the optical waveguide layer formed of ₀ changes continuously or intermittently in the light guiding direction is repeated with a large cycle (Japanese Patent Application No. 4-213).
No. 084), whereby a region in which the equivalent refractive index of the optical waveguide changes continuously or intermittently from n _a to n _{b in the} light guiding direction is repeated at the period M _f. A semiconductor laser device having at least one reflectance peak from the wavelength λ _a (= 2n _a Λ) to the wavelength λ _b (= 2n _b Λ) can be formed by the refractive index.

[0019]

EXAMPLES Example 1 Groove Width Modulation Tandem DFB Laser In this example, a ridge width dw and a height h are made constant, and a groove width dg is changed in five ways to manufacture a 5-wavelength semiconductor laser. is there. FIG. 2 shows a procedure for producing the 5-wavelength semiconductor laser according to this embodiment.

First, as shown in FIG. 2A, a diffraction grating 2 is formed on an InP substrate 1. The diffraction grating 2 has a width of 5 μm
And the cycle is 2400Å, 23 for each 300μm.
It changes to 00Å, 2200Å, 2100Å, 2000Å. When electron beam lithography is used, not only a uniform diffraction grating but also a diffraction grating whose period changes according to the ridge width, height and groove width are formed in the portion where the ridge is formed. The InP substrate 1 has an optical waveguide layer before forming a diffraction grating,
For example, the InGaAsP layer may be crystal-grown, in which case the corresponding optical waveguide layer growth step is omitted in the subsequent crystal growth.

Next, as shown in FIG. 2B, the diffraction grating 2
A pattern made of an oxide film or a nitride film 3 is formed by photolithography on the n-type InP (100) substrate 1 on which the above is formed. This pattern is a plate-shaped mask having a stripe portion that becomes a ridge and a staircase in a part that sandwiches the stripe portion. Subsequently, as shown in FIG. 2C, a groove width modulation type non-flat substrate having ridges 4 and grooves 5 is formed by dry etching using chlorine gas. Here, the ridge 4 is formed in the <011> direction (so-called reverse mesa direction), the ridge width dw is 1.5 μm, and the ridge height h is 2 μm. The groove width dg is 1.5 μm, 3.0 μm, 3.5 μm, 4.0 μ at every 300 μm.
m, 10.0 μm.

After that, as shown in FIG. 2D, In is formed on a groove width modulation type non-flat substrate having ridges 4 and grooves 5.
A light emitting layer 6 and a p-InP clad layer 7 having a strained quantum well structure composed of an optical waveguide layer of GaAsP and an InGaP barrier of 30 Å / 150 Å of 30 Å of 5 periods are formed. The light emitting layer 6 and the clad layer 7 are formed of a metalorganic vapor phase at 630 ° C. and 0.1 atm using trimethylindium, trimethylgallium, arsine, and phosphine as source gases for semiconductors and hydrogen selenide and diethylzinc as doping gases. It is formed by the growth method.

The emission spectrum on the flat substrate observed by the photoluminescence method has a peak at 1.3 mm, while the adjacent groove widths are 1.5 μm and 3.0 μm.
The peaks of light emission from the ridge at 3.5 μm, 4.0 μm and 10.0 μm are 1.55 μm,
1.5μm, 1.45μm, 1.4μm, 1.35μm
become. Further, according to FIG. 2 (E), after p-InP clad layer 7'is additionally deposited by metalorganic vapor phase epitaxy,
N-InP layer 8 and p-InP layer 9 for current blocking
Then, a p-InGaAsP contact layer 10 is formed.

The crystal growth shown in FIGS. 2D and 2E can be performed once depending on the conditions, but when the thickness of the buried layer, the doping control, etc. are accurately performed, the growth can be performed in two or three times. To do. As shown in FIG. 2 (F), a p-electrode 11 and an n-electrode 11 'are formed on the upper and lower sides, and a separation groove 12 is provided to separate respective portions on the ridge where the composition changes. Thus the element manufactured by mounting on the heat sink 13, further I from I ₁ after Bondengu wire 14
_When current injection of ₅ is performed, laser oscillation characteristics such as A ₁ to A ₅ as shown in FIG. 3 are obtained from the A surface indicated by an arrow in FIG. 2 (F) according to each current injection. .

The oscillation wavelength is a light emission with good directivity corresponding to the composition that is in agreement with the photoluminescence measurement result.
Also, from the opposite surface B, 1.5 as shown by B in FIG.
Emission at 5 μm is mainly observed. This is because light with a short wavelength emitted from the front surface is absorbed in the area on the opposite side.

(Embodiment 2) Ridge width modulation type tandem DF
B laser This embodiment relates to a 5-wavelength integrated DFB laser in which the groove width dg and the ridge height h are fixed and the ridge width dw is changed in five ways. FIG. 4 shows a procedure for producing the 5-wavelength integrated DFB laser according to this embodiment. A diffraction grating 2 is formed in advance on the InP substrate 1 as shown in FIG.

First, as shown in FIG. 4B, n-type In
A pattern made of an oxide film or a nitride film 3 is formed on the P (100) substrate 1 by photolithography. This pattern is a plate-like mask having a polygonal stripe portion which becomes a ridge and a staircase in a part sandwiching the polygonal stripe portion.
Next, as shown in FIG. 4C, the ridge 4 and the groove 5 are formed in the same manner as in Example (1). Ridge 4 is 1 μm,
It has 5 kinds of widths dw of 2 μm, 3 μm, 4 μm, and 10 μm, is formed in the <011> direction (so-called reverse mesa direction), and the height h of the ridge 4 and the groove width dg are 2 μm and 2.5 μm, respectively. ing.

Subsequently, as shown in FIG. 4D, a light emitting layer having a strained quantum well structure composed of an InGaAsP optical waveguide layer and five periods of 30Å InGaP well / 150Å InGaAsP barrier as in Example (1). 6, p-InP clad layer 7, and n-InP layer 8 for current blocking. Ridge width 1μm, 2μm, 3μm, 4μm, 10μ
The peak wavelength of the emission spectrum obtained by the photoluminescence measurement of the crystal formed on the ridge of m is 1.55 μm, 1.5 μm, 1.45 μm, and 1.4, respectively.
μm, 1.35 μm.

Then, in order to obtain an embedded structure, FIG.
After forming the oxide film or the nitride film 3 as shown in (B '), dry etching is performed as shown in FIG. 4 (D'). The buried growth and the electrode formation are the same as in the case of the first embodiment, and the shapes are similar to those in FIGS. 2 (E) and (F).
The laser oscillation characteristic is also as shown in FIG.

(Embodiment 3) Ridge height modulation type tandem D
FB laser This embodiment relates to a modulation tandem DFB laser in which the ridge width dw and the groove width dg are made constant and the ridge height h is changed in five ways. FIG. 5 shows a manufacturing procedure of the modulation tandem DFB laser of this embodiment. On the InP substrate 1,
The diffraction grating 2 is formed in advance as shown in FIG.

First, as shown in FIG. 5B, n-type In
A pattern made of an oxide film or a nitride film 3 is formed on the P (100) substrate 1 by photolithography. This pattern is a plateau-like mask having stairs in a part that sandwiches the part that becomes the ridge. Next, as shown in FIG.
The ridge 4 and the groove 5 are formed by selectively growing n-InP between the masks by a metal organic chemical vapor deposition method or a metal organic molecular beam epitaxy method. At this time, since the growth rate changes according to the width of the mask, a step is formed in the height h of the ridge 4. The ridge 5 is 1.2 μm, 1.4 μm,
Five types of height h of 1.6 μm, 1.8 μm and 2.0 μm
Is formed in the <011> direction (so-called reverse mesa direction), and the ridge width dw is 1.5 μm.

Subsequently, in order to make the groove width dg constant,
A pattern made of an oxide film or a nitride film 3 as shown in FIG. 5 (B ') is formed, and as shown in FIG. 5 (A'), it is formed on a ridge of a non-flat substrate in which only the height of the ridge is changed by dry etching. Form a diffraction grating. Here, the groove width dg is 2.5 μm, and the period of the diffraction grating is 2400Å, 230
0Å, 2200Å, 2100Å, 2000Å. Further, as shown in FIG. 5D, a light emitting layer 6 having a strained quantum well structure composed of an InGaAsP optical waveguide layer and five periods of 30Å InGaP well / 150Å InGaAsP barrier as in Example (1), A p-InP clad layer 7 is formed.

Height 1.2 μm, 1.4 μm, 1.6 μ
The peak wavelengths of the emission spectra obtained by the photoluminescence measurement of the crystals formed on the ridges of m, 1.8 μm, and 2.0 μm are 1.35 μm and 1.4 μm, respectively.
m, 1.45 μm, 1.5 μm, 1.55 μm.
After that, the buried growth and the electrode formation are the same as in the first embodiment.
This is performed as shown in FIGS. 2 (E) and (F). The laser oscillation characteristics are similar to those in FIG.

FIG. 6 shows another modification in which modulation is performed by the height h of the ridge. In this modified example, as shown in FIG. 6B, the mask shown in FIG. 5B is left-right interchanged, and as a result of selective growth, as shown in FIG. 6C, the ridge width dw A non-planar substrate view with varying height h is formed. In order to make the ridge width dw constant, a pattern made of an oxide film or a nitride film 3 as shown in FIG. 6B 'is formed,
By dry etching, a non-flat substrate in which only the height of the ridge changes is obtained. Hereinafter, a procedure similar to the procedure described above is performed.

(Embodiment 4) Embodiment 4 of the present invention is shown in FIG. As shown in FIG. 12, on the InP semiconductor waveguide, a uniform pitch (Λ ₀ = 2389Å) and a uniform depth (500
The diffraction grating 15 of Å) is formed and two grooves 17 having a certain pattern are formed. Two grooves 17
Is formed in a stripe shape on the semiconductor substrate and continuously changed with a period (Λ _s = 75 μm) larger than the uniform pitch of the diffraction grating 15 in the stripe direction. Therefore, the groove width dg of the two grooves 17 is 2 μm.
To 5 μm periodically. The two grooves 17
The groove width may change stepwise. The depth of the two grooves 17,
That is, the height h of the ridge 18 sandwiched between the two grooves 17 is
It is constant at 3 μm. Continuing, two such grooves 17
A quantum well structure having a bandgap composition of 1.5 μm when grown on a normal semiconductor substrate is selectively grown on the central stripe region on which the ridge 18 is formed.

As a result, the refractive index in the ridge 18 sandwiched by the two grooves 17 is as shown in FIG. 9 (c).
With a period equal to the period (75 μm) of the groove 17, the refractive index n _a
= 3.20 to the refractive index n _b = 3.29. After that, 1 μm of InP clad layer is formed on the entire surface.
m. As a result, the quantum well and the cladding layer grow only in the ridge 18, and a ridge-type waveguide is formed in a self-aligned manner. The diffraction grating 15 may be formed on the waveguide. This ridge waveguide acts as a distributed reflector, and its transmission characteristic has a wavelength λ _a (=
2n _a Λ ₀ = 1.52896 μm) to the wavelength λ _b (= 2n _b
A reflector with a plurality of high reflectance peaks is obtained, with one or more reflectance peaks by Λ ₀ = 1.571962 μm).

(Fifth Embodiment) FIG. 9 shows a fifth embodiment of the present invention.
Shown in (a) and (b). As shown in FIGS. 9A and 9B, a uniform pitch (Λ ₀ = 2389) is formed on the InP semiconductor waveguide.
In step Å), the diffraction grating 15 having a uniform depth of 500 Å is formed and the insulating film mask 16 having a constant pattern is formed. The insulating film mask 16 shown in FIG. 9A removes a part of the insulating film formed over the entire surface of the semiconductor substrate in a stripe shape, and has a period (Λ) larger than the uniform pitch of the diffraction grating 15 in the stripe direction. _s = 75 μm). Further, the insulating film mask 16 shown in FIG. 9B is formed in a stripe shape on the semiconductor substrate and has a continuous period (Λ _s = 75 μm) larger than the uniform pitch of the diffraction grating 15 in the stripe direction. It has been changed to. The stripe-shaped change of the insulating film mask 16 may be stepwise. A quantum well structure having a bandgap composition of 1.5 μm when grown on a normal semiconductor substrate is formed on the stripe region in the center of the selective growth layer on the diffraction grating 15 and the insulating film mask 16 thus formed. It selectively grows as 19 (see FIGS. 10A and 10B).
As a result, the refractive index (X-X 'direction in the figure) in that region is set to the insulating film mask 1 as shown in FIG. 9 (c).
With a period equal to the period of 6 (7.5 μm), the refractive index n _a =
It changes periodically from 3.20 to the refractive index n _b = 3.29.

After that, as shown in FIGS. 10A and 10B, the insulating film mask 16 is removed, and the InP clad layer 20 is formed to a thickness of 1 μm on the entire surface. As shown in FIG.
A region where the composition is changed is processed into a ridge waveguide shape. This ridge waveguide functions as a distributed reflector, and its transmission characteristic has a wavelength λ _a (= 2n _a Λ ₀ =
1.52896 μm) to the wavelength λ _b (= 2n _b Λ ₀ = 1.
Reflectors with a plurality of high reflectance peaks, with one or more reflectance peaks up to 571962 μm) are obtained.

[0039]

As described above in detail based on the embodiments, a DFB laser integrated at high density is realized by the present invention, which is suitable for communication and optical measurement utilizing the high wavelength band property. A dramatic development is expected. Further, according to the present invention, the waveguide portion of the semiconductor laser device having a plurality of reflection peaks can be obtained by performing the crystal growth once by using the substrate on which the diffraction grating having the uniform pitch and the depth is formed. .

[Brief description of drawings]

FIG. 1 is an In _1-x Ga _x As / In formed on a non-planar substrate.
Regarding the shift amount of the emission wavelength of the GaAsP (λg = 1.1 μm) MQW layer, (A) shows the ridge width dependence of the shift amount of the emission wavelength at various groove widths, and (B) shows the emission wavelength at various ridge widths. FIG. 3C is a graph showing the groove width dependence of the shift amount, and FIG. 6C is a graph showing the ridge height dependence of the emission wavelength shift amount at various ridge widths.

FIG. 2 relates to a method of manufacturing a 5-wave integrated DFB laser (groove width modulation method) according to Example 1 of the present invention, (A) is a diffraction grating formation, (B) is a mask formation (for etching), (C). Is a non-flat substrate (groove width modulation type), (D) is crystal growth (formation of light emitting layer), (E) is crystal growth (embedded growth), and (F) is a process chart showing an electrode formation procedure.

FIG. 3 is a graph showing oscillation characteristics of a 5-wave integrated DFB laser.

FIG. 4 relates to a method of manufacturing a 5-wave integrated DFB laser (ridge width modulation method) according to a second embodiment of the present invention, (B) is mask formation (for etching), and (C) is a non-flat substrate (ridge width modulation). Type), (D) is crystal growth (formation of light emitting layer),
(B) 'is a process diagram showing a procedure for forming a mask (for etching) and (D') for forming a non-flat substrate before embedding.

FIG. 5 relates to a method of manufacturing a 5-wave integrated DFB laser (ridge height modulation method 1) according to a third embodiment of the present invention, (B) is mask formation (for selective growth), and (C) is a non-flat substrate ( (After removing the mask), (B ') is for mask formation (for etching),
(A ') is a process chart showing a procedure of a non-flat substrate with a diffraction grating (ridge height modulation type), and (D) crystal growth (formation of a light emitting layer).

FIG. 6 is a five-wave integrated DF according to a modification of the third embodiment of the present invention.
Regarding the manufacturing method of the B laser (ridge height modulation method 2),
(B) is a process diagram showing a procedure for mask formation (for selective growth), (C) a non-flat substrate (after mask removal), and (B ') for mask formation (for etching).

FIG. 7A is a schematic diagram of selective growth on a semiconductor substrate having an insulating mask of a conventional example, and FIG. 7B is a graph showing the relationship between the bandgap wavelength of the selectively grown region and the width of the insulating film mask. c) is a graph showing the relationship between the growth rate and the width of the insulating film mask.

8A and 8B are explanatory diagrams showing an insulating film mask pattern formed on a diffraction grating, and FIG. 8C is an explanatory diagram showing a groove pattern formed on a substrate.

FIG. 9 relates to Example 5 of the present invention, (a) and (b) are explanatory views showing an insulating film mask pattern formed on a diffraction grating, and (c) is XX ′ formed after selective growth. 5 is a graph showing the change in the refractive index of

FIG. 10 relates to Example 5 of the present invention, (a) and (b) are explanatory views showing a state in which an InP clad layer is grown over the entire surface after removing the insulating film mask, and (c) is a ridge type distributed reflection laser. FIG.

FIG. 11 is a graph showing a reflector characteristic of a ridge type distributed reflector.

FIG. 12 is an explanatory view showing a shape before growth, which uses a groove structure in Example 4 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Diffraction grating 3 Oxide film or nitride film 4 Ridge 5 Groove 6 InGaAs / InGaAsP light emitting layer and optical waveguide layer 7, 7'p-InP clad layer 8 n-InP layer 9 p-InP layer 10 Contact layer 11, 11 ′ Electrode 12 Element isolation groove 13 Heat sink 14 Lead wire 15 Diffraction grating 16 Insulating mask 17 Groove 18 Ridge 19 Selective growth layer 20 InP clad layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Naganuma 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. A width of 1 to 10 μm formed on a semiconductor substrate
Width 1-3 μm, height 1-3 μm between two grooves
In an optical device that utilizes the change in the light emission characteristics of the semiconductor multilayer film formed on the ridge, the same emission surface is formed by growing several different crystals in the cavity direction and forming a diffraction grating to match them. A semiconductor laser device which emits laser light of a plurality of wavelengths from the semiconductor laser device. 2. A semiconductor laser device according to claim 1, further comprising a light guide layer on an upper portion of the ridge. 3. A semiconductor substrate on which a diffraction grating having a uniform pitch Λ ₀ and a uniform depth is formed, and the width of the region sandwiched between the two grooves is constant, and both groove widths or grooves are formed. Is formed so that the depth of the groove is symmetric with respect to the groove direction and the groove width or the groove depth changes continuously or intermittently with respect to the groove direction and is repeated with a large period Λ _s. And a different bandgap composition in regions having different groove widths or groove depths by crystal growth of a quantum well waveguide structure thereon. The quantum well waveguide layer in which a region in which the refractive index changes continuously or intermittently with respect to the groove direction from n _a to n _b is repeated with the period Λ _s. , At least wavelength λ _a (= 2 from n _a Λ ₀ ) to the wavelength λ _b (= 2n _b
A method for manufacturing a semiconductor laser device, which comprises forming a distributed reflector having one or more reflectance peaks by Λ ₀ ). 4. A semiconductor substrate having two grooves sandwiched between them.
The width of the encircled area is constant, and the width of both grooves is not great
Depth is symmetric with respect to the groove direction, and the groove width is
The groove depth is continuous or intermittent with respect to the groove direction.
Period Λ where the changing region is large_sShaped as repeated in
It is characterized by using the formed structure, and on top of that quantum well
The above-mentioned two grooves are formed by crystal-growing the door waveguide structure.
Areas with different groove widths or groove depths
Creates a waveguide layer with a different bandgap composition in the region,
The refractive index is n with respect to the direction of the groove._aTo n_bUp to continuous
Is the period Λ_sRepeated in
The grown quantum well waveguide layer and then a uniform pitch.
Chi Λ₀Then, put a diffraction grating of uniform depth between the two grooves.
Formed on the waveguide layer in the
At least wavelength λ _a(= 2n_aΛ₀) From the wavelength λ_b(= 2n
_bΛ₀) Distributed reflection with one or more reflectance peaks by
Method for manufacturing a semiconductor laser device that forms a container.