JPH09321382A - Laser beam source and application thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the temperature dependency of the waveform of a semiconductor laser while ensuring a wide stabilized temperature range by disposing a reflector having at least two reflective surfaces oppositely to at least one reflective surface of the semiconductor laser. SOLUTION: A laser chip 111 is provided, on the front surface thereof, with a front reflective film 112 of multilayer dielectric having reflectance of 9% for a laser beam and, on the rear surface thereof, with a rear reflective film 113 of multilayer dielectric having reflectance of 50% for the laser beam and then the laser chip 111 is bonded through an In based solder to an Si submount 114. When a semiconductor laser is oscillated, a double external resonator mode formed by the front and rear surfaces of a glass plate is superposed on the longitudinal mode of the semiconductor laser itself. This composite mode satisfies both a narrow half peak width and a wide interval between modes of same intensity. Furthermore, increase of the threshold value due to temperature increase can be canceled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser used as a light source for a laser printer, an optical disk, optical measurement, etc. and its application device.

[0002]

2. Description of the Related Art A conventional external resonator type laser light source is shown in FIG.
The reflecting surface 4 is provided so as to face the rear end surface of the semiconductor laser 2 as shown in (1) to form an external resonator having a narrow resonance wavelength range and stabilize the oscillation wavelength of the semiconductor laser. In FIG. 15, 1 is a heat sink and 3 is Ga.
The mirror chip 4 made of As has an end face coating (A
1 ₂ O ₃ / a-Si 95%).

[0003]

In the above conventional technique, the resonance wavelength of the external resonator is determined only by the distance between the semiconductor laser and the back reflecting surface. In this case, the distance between the resonance wavelengths and the sharpness of the resonance wavelength are both determined by this distance. Therefore, if this distance is increased, mode hopping easily occurs between the external resonator modes and the wavelength stability deteriorates. On the other hand, if this distance is shortened, the distance between the external resonator modes becomes wider, so that mode hopping between the external resonator modes is less likely to occur, but the width of the external resonator modes becomes wider, so that the semiconductor lasers in the same external resonator mode are A wavelength change corresponding to the change of the gain spectrum occurred.
This distance was determined by the positional accuracy with which these parts were attached to the submount such as Si, but this positional accuracy was larger than the wavelength of the laser light, so it was impossible to control the peak value of the resonator wavelength. . Therefore, the conventional technique has a problem that, even if the wavelength is stable, it causes variations in characteristics in relation to the gain of the semiconductor.

In the present invention, the controllability of the wavelength is increased by solving the above-mentioned problems of the prior art. A second point is to provide a technique for compensating not only the wavelength stability but also the temperature characteristic of the semiconductor laser itself. Thirdly, the purpose of applying such a technique to an array type device having a plurality of oscillation regions is to be applied.

[0005]

According to the present invention, a reflector having at least two reflecting surfaces is provided facing one reflecting surface of a semiconductor laser. For laser oscillation, at least one resonance wavelength of an optical resonator formed by one of the reflecting surfaces of the reflector and the reflecting surface of the semiconductor laser or the reflecting surface of the reflector is set to the optical gain spectrum of the semiconductor structure. Control within half width. Furthermore, of the two resonators,
It is preferable to control the resonance wavelength of the shortest effective light wavelength within the half width of the optical gain spectrum of the semiconductor structure.

As a second point, by setting the resonance wavelength of the resonator having the shortest optical path length to a wavelength longer than the peak wavelength of the gain spectrum at the maximum operating temperature of the semiconductor laser, the normal semiconductor laser can be used. It was also possible to compensate for variations in operating current due to changes in temperature.

Thirdly, if such a technique is applied to an array type laser in which semiconductor lasers that can be individually driven are integrated, the wavelength can be stabilized and the function of canceling crosstalk between elements can be produced. Such control of the shortest cavity length is (1) controlling the distance between the semiconductor laser and the reflector formed by the protrusions formed on the base body, (2) controlling the thickness of the reflector, and (3). This can be performed by various methods such as providing a recess in the reflector provided in close contact with the reflecting surface of the semiconductor laser and controlling the depth of the recess. By using such a semiconductor laser, the output monitor for temperature characteristic compensation and the color correction of the optical system, which were required in the conventional semiconductor laser application device, are not required, and the optical application device is downsized,
It was effective in lowering the price.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A first embodiment of the present invention will be described with reference to the drawings.
1 and 2 are plan views showing a cross-sectional structure intersecting the optical axis of a semiconductor laser chip used as a light source and a mounting arrangement, respectively.
In this structure, first, n- (Al
_0.5 Ga _0.5 ) _0.5 In _0.5 P cladding layer 102, multiple quantum well active layer 103, p- (Al _0.5 Ga _0.5 ) _0.5 In _0.5
P cladding layer 104, p-GaAs contact layer 105
Were sequentially grown. The multi-quantum well active layer 103 has three Ga _0.5 In _0.5 P well layers (7 nm) and four (Al) layers.
It is formed by alternately laminating _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layers (4 nm). Next, a SiO ₂ mask is formed on this structure by using a thermal CVD method and a photolithographic technique. Using this SiO ₂ mask, the p-GaAs contact layer 105 and p- (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P are formed.
After etching a part of the cladding layer 104, again by MOCVD the SiO ₂ as a mask n-
The GaAs block layer 106 was selectively grown. A region where the protrusions of the layer 104 and the layer 105 remain is a region left by the mask. In order to reduce the series resistance of the device, after removing the SiO ₂ film, p-In _0.5 Ga _0.5 P
107 and a p-GaAs buried layer 108 were formed. An electrode 109 containing Au as a main component is formed on the surface of the wafer, and a GaAs substrate is about 1 by mechanical polishing and chemical etching.
Etching was performed to a depth of 00 μm, and an electrode 110 containing Au as a main component was also formed on the GaAs substrate side. Such a semiconductor wafer is cleaved into bars at intervals of about 600 μm and
The chips were separated at intervals to make laser chips.

Laser chip 1 produced as described above
As shown in FIG. 2, a front reflection film 112 made of a dielectric multilayer film having a reflectance of 9% with respect to the laser light is provided on the front surface of 11, and a rear surface made of a dielectric multilayer film having a reflectance of 50% with respect to the laser light on the rear surface. A reflective film 113 was provided and was bonded to the Si submount 114 using In solder as shown in FIG. On the rear surface side of the laser chip, a glass plate 115 having a thickness of about 100 μm is attached in parallel with the end surface of the semiconductor laser at intervals of 41 to 41.5 μm. The glass plate 114 is provided with a dielectric multilayer film 116 having a reflectance of 50% on the semiconductor laser side and a dielectric multilayer film 117 having a reflectance of 100% on the reflecting side of the semiconductor laser. The laser chip and the glass plate can be set at an exact distance of 41 to 41.5 μm by the projection 118 formed on the Si submount by using the photolithography technique. The structure of the reflective film itself may be a known method.

The protrusion 118 of the Si submount was formed as follows. First, a SiO ₂ film 120 having a thickness of 2 μm was formed on a Si wafer 119 by a thermal gas phase reaction, and then a photomask pattern having a width of 41 μm was formed using a photolithographic technique, and the SiO ₂ film 120 was etched by a reactive ion etching method. Next, Si is etched by about 10 μm using the SiO ₂ film 120 as a mask to form a sectional structure as shown in FIG. There is almost no side etching of the SiO ₂ film 120 due to the reactive ion etching, and the distance between the laser chip 111 and the glass plate 115 is defined by the width of the SiO ₂ film 120.
It is possible to easily perform highly accurate position control of 41.5 μm.

When the semiconductor laser is oscillated in the above-described state, the external mode of the semiconductor laser itself is a double external mode of the resonator mode 121 formed by the front surface and the resonator mode 122 formed by the rear surface of the glass plate. The resonator mode is heavily responsible. FIG. 4 shows an external resonator mode in which two external resonance modes are combined. The resonator mode 122 formed by the rear surface of the glass plate has a small mode interval but a small mode width. On the other hand, since the resonator formed by the front surface of the glass plate has a wide mode interval, the combined modes of the two can achieve both a narrow half width and a wide interval with another mode having the same intensity.
At this time, it was necessary to control so that the effective resonator length was within the peak wavelength of the shorter resonator and the half-value width of the gain spectrum of the semiconductor. However, according to the present invention, mode hopping did not occur in the range of 0 to 100 degrees, and a wavelength change with temperature of 0.01 nm / ° C was realized.

Further, in this embodiment, the temperature characteristic is compensated by accurately aligning the position of the glass plate.
Gain spectrum of semiconductor laser at room temperature (25 degrees) 12
The maximum value of 3 was at a wavelength of 685 nm, and the closest external resonator mode was 687.5 nm. When the temperature of the semiconductor laser rises, the threshold current usually increases, but in the case of this embodiment, the maximum value 124 of the gain spectrum of the semiconductor laser at this temperature is 0.3 nm /
Since it moves to the long wavelength side at ℃, the matching with the external resonator is improved, and the rise in the threshold value due to the rise in temperature is canceled out. Due to such compensation effect, an element in which the characteristics of the semiconductor laser apparently do not depend on temperature can be realized. In the present embodiment, the Fabry-Perot type laser having a pair of reflecting surfaces formed by the cleaved surface of the semiconductor laser has been described, but a ring laser having three or more reflecting surfaces or a distributed feedback laser having a plurality of reflecting structures. Also in, the same effect can be obtained by applying the present invention.

(Embodiment 2) A second embodiment of the present invention will be described with reference to the drawings. 5 and 6 are plan views showing the sectional structure and mounting arrangement of the semiconductor laser chip used as the light source, respectively.
In this structure, first, n- (Al
_0.5 Ga _0.5 ) _0.5 In _0.5 P cladding layer 102, multiple quantum well active layer 103, p- (Al _0.5 Ga _0.5 ) _0.5 In _0.5
P cladding layer 104, p-GaAs contact layer 105
Were sequentially grown. The multi-quantum well active layer 103 has three Ga _0.5 In _0.5 P well layers (7 nm) and four (Al) layers.
It is formed by alternately laminating _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layers (4 nm). Next, two stripes of Si are formed on this structure by using a thermal CVD method and a photolithographic technique.
O ₂ masks are formed at intervals of about 10 μm. Using this SiO ₂ mask, the p-GaAs contact layer 105 and p
-(Al _0.5 Ga _0.5 ) _0.5 In _0.5 P A part of the clad layer 104 is etched. The area designated by 105 in FIG. 5 is the area left by the mask. After that, the n-GaAs block layer 106 was selectively grown again by metalorganic vapor phase epitaxy using the SiO ₂ as a mask. In order to reduce the series resistance of the device, after removing the SiO ₂ film, p-G
The aAs embedded layer 108 was formed. The electrode 109 containing Au as a main component is formed on the surface of the wafer, the GaAs substrate is etched to about 100 μm by mechanical polishing and chemical etching, and the electrode 1 containing Au as a main component is also formed on the GaAs substrate side.
Formed 10. About 600μ of such semiconductor wafer
Cleaved into bars at m intervals and laser chips separated at 300 μm intervals.

On the front surface of the laser chip manufactured as described above, the front reflection film 112 having a reflectance of 9% with respect to the laser light.
A rear reflection film 113 having a reflectance of 50% with respect to the laser light is provided on the rear surface of the Si submount 1 using In-based solder.
It was adhered to 14 as shown in FIG. On the rear surface side of the laser chip, a reflector plate 201 having a thickness of about 30 μm is attached at intervals of about 100 μm in parallel with the end surface of the semiconductor laser.
The reflector 201 has a thickness of about 100 as shown in the sectional view of FIG.
A highly reflective film 203 formed by stacking Si ₃ N ₄ and SiO ₂ on a glass substrate 202 of μm, a SiO ₂ film 204 for phase control, and formed by depositing Si ₃ N ₄ and SiO ₂ 50 % Reflection film 205.

When the semiconductor laser is oscillated in the above-described state, the double external resonator mode formed by the high reflection film 203 and the 50% reflection film 205 of the reflection plate 201 is added to the longitudinal mode of the semiconductor laser itself. Pile up. The two external resonator modes and the external resonator mode in which they are combined are as shown in FIG. 4 as in the first embodiment. As shown in the figure, in the composite external resonator mode, the width of each mode is defined by the resonator formed by the rear reflection film 113 of the semiconductor laser and the 50% reflection film 205, and the modes up to other modes of the same intensity are obtained. In order to obtain a good laser characteristic formed by the high reflection film 203 and the 50% reflection film 205, the interval is the length of the resonator having the shorter resonator length, and the peak of the resonance wavelength is the gain spectrum of the semiconductor. It was necessary to control it so that it was within the half-width. Since it is defined by the external resonator mode, a wide mode interval and a narrow spectral width can both be achieved. As a result, mode hopping did not occur in the range of 0 to 100 degrees, and a wavelength change due to temperature of 0.01 nm / ° C was achieved.

The structure of the reflection plate is the same as that of the optical etalon except that it is divided into chips, and a large amount can be produced by dividing the chips into chips after forming the reflection plate on a large-diameter substrate. It was possible to form. It was also possible to compensate for the temperature characteristic by precisely matching the reflection wavelength of the etalon as in the first embodiment.

Further, in the case of the present embodiment, since the individual wavelengths of the arrayed semiconductor lasers are determined by the external resonator, it is not necessary to perform color correction for each stripe, and the temperature characteristics are compensated, so that the conventional method is used. The problem of crosstalk between stripes, which was a problem with the array lasers of the above, was also solved.

Next, an example in which the present array element is used as a light source for a laser beam printer as shown in FIG. 16 will be described. In FIG. 16, 5 is a semiconductor laser light source, 612 optical system, 7 is a polygon mirror, 8 is a scanning lens system, and 9 is a photosensitive drum. In order to speed up the laser beam printer, it is effective to simultaneously scan a plurality of lines by using an array element having a plurality of laser stripes.
However, in the array element, so-called thermal crosstalk is a problem in which the individual stripes are not driven independently of each other due to thermal mutual interference and the driving state of one stripe affects the characteristics of the other. However, if the characteristics are stabilized according to the present invention, the characteristics of a plurality of stripes can be stabilized at one time, so that the problem of thermal stability as described above can be easily solved.

(Embodiment 3) A third embodiment of the present invention will be described with reference to the drawings. The sectional structure and mounting arrangement of the semiconductor laser chip used as the light source are shown in FIGS. In this structure, first, an n-Al _0.5 Ga _0.5 As cladding layer 301, a multiple quantum well active layer 302, and p-Al are formed on an n-GaAs substrate 101.
_{The 0.5} Ga _0.5 As clad layer 303 and the p-GaAs contact layer 105 were sequentially crystal-grown. The multiple quantum well active layer 302 is composed of three Ga _0.9 Al _0.1 As well layers (7 nm).
And four Ga _0.7 Al _0.3 As barrier layers (4 nm) are alternately laminated. Then, two stripes S are formed on this structure by using a thermal CVD method and a photolithographic technique.
An iO ₂ mask is formed with a spacing of about 10 μm. This SiO ₂
After the p-GaAs contact layer 105 and a part of the p-Al _0.5 Ga _0.5 As clad layer 303 are etched using a mask, the n-GaAs block layer 106 is formed again by metalorganic vapor phase epitaxy using this SiO ₂ as a mask. Selectively grown. In order to reduce the series resistance of the device, the SiO ₂ film was removed and then the p-GaAs buried layer 108 was formed. An electrode 109 containing Au as a main component is formed on the surface of the wafer,
The GaAs substrate was etched to about 100 μm by mechanical polishing and chemical etching, and the electrode 110 containing Au as a main component was also formed on the GaAs substrate side. Such a semiconductor wafer is cleaved into bars at intervals of about 600 μm,
Chips were separated at m intervals to obtain laser chips.

On the front surface of the laser chip manufactured as described above, a front reflection film 112 having a reflectance of 9% for laser light is formed.
A rear reflection film 113 having a reflectance of 50% with respect to the laser light is provided on the rear surface of the Si submount 1 using In-based solder.
14 was adhered as shown in FIG. A depth of 41 to 41.5 μm is provided on the rear surface of the laser chip and a thickness of about 1 is provided.
A glass plate 305 of 00 μm is attached, a high reflection film 203 on the rear surface of the glass plate, and a 50% reflection film 2 on the front surface.
05 is formed.

When the semiconductor laser is oscillated in the above-mentioned state, the double external resonator mode formed by the high reflection film 203 and the 50% reflection film 205 of the reflection plate 305 has a heavy influence on the longitudinal mode of the semiconductor laser itself. To do. The two external resonator modes and the external resonator mode in which they are combined are as shown in FIG. 4 as in the first embodiment. As shown in the figure, the width of each of the composite external resonator modes is high in the reflective film 203.
And a mode interval up to another mode of the same intensity defined by the resonator formed by the 50% reflection film 205 and the external cavity mode formed by the 50% reflection film 205 and the laser rear reflection film 113. Therefore, in order to obtain good laser characteristics that can achieve both a wide mode interval and a narrow spectral width, the resonance wavelength of the resonator formed by the 50% reflective film 205 having a short resonator length and the laser rear surface reflective film is set to the gain spectrum of the semiconductor. It was necessary to set it within the half-width of. As a result, mode hopping does not occur in the range of 0 to 100 degrees and the wavelength change with temperature is 0.01 nm /
The value of ℃ was achieved. The depth of the recess of the glass plate is exactly 50 to 50.5 μm by the reactive ion etching method.
It was possible to control to m. It is needless to say that the same effect as that of the first embodiment can be obtained according to the present embodiment although the wavelength is different.

(Embodiment 4) A fourth embodiment of the present invention will be described with reference to the drawings. A sectional structure and a top view of the semiconductor laser chip used as the light source are shown in FIGS. In this structure, first, p-Al _0.2 Ga is formed on the p-SiC (6H) substrate 401.
_0.8 N cladding layer 402, multiple quantum well active layer 403,
The n-Al _0.2 Ga _0.8 N cladding layer 404 and the n-GaN contact layer 405 were sequentially crystal-grown. The multiple quantum well active layer 403 is composed of 7 layers of Al _0.1 Ga _0.7 In _0.2 N well layers (2 nm) and 8 layers of Al _0.3 Ga _0.7 N barrier layers (2n).
m) are alternately laminated.

On the surface of the p-SiC substrate, an n-SiC layer 406 having a thickness of about 0.5 μm is provided by phosphorus implantation, and only a stripe region serving as a waveguide of the semiconductor laser has a width of about 3 μm and a height of 1 μm. Two ridges 407 are formed in parallel at intervals of 10 μm. When crystal growth is performed on a substrate having such a step, the active layer 403 is also formed as shown in FIG.
A step like 0 is formed, and this becomes an optical waveguide structure.
The optical waveguide structure using such a step causes a reliability problem in other material systems such as AlGaAs system and AlGaInP system, but if the defect density is 10 ⁷ or less per square centimeter, sufficient reliability can be obtained. With this structure, a sufficiently reliable semiconductor laser can be obtained in the GaN-based crystal.

Electrode 1 containing Au as a main component on the surface of the wafer
09 is formed, and S is formed by mechanical polishing and chemical etching.
Etching the iC substrate 401 to about 100 μm,
The electrode 110 containing Au as a main component was also formed on the s substrate side. Next, a groove 407 having a width of 30 μm is formed in this wafer by the reactive ion etching method. The wall surface of the groove is vertically processed to act as a reflecting surface. Such a wafer was cleaved so that a laser stripe of about 50 μm remained behind the groove. 9 against the laser light on the front of the laser chip
The front reflection film 112 having a reflectance of 100% and the rear reflection film 113 having a reflectance of 100% with respect to the laser light are provided on the rear surface.

When the semiconductor laser having the above structure is oscillated, the longitudinal mode of the semiconductor laser itself is heavily responsible for the double external resonator mode formed by the reflection on the front and rear surfaces of the groove. The two external resonator modes and the external resonator mode in which they are combined are as shown in FIG. 4 as in the first embodiment. As shown in the figure, the composite external cavity mode has a width of 50% for each mode.
The mode interval up to another mode of the same intensity defined by the resonator formed by 13 is defined by the external resonator mode formed by the 50% reflective films 205, so that a wide mode interval and a narrow spectral width can both be achieved. . In order to obtain good laser characteristics, it is necessary to control the resonance wavelength of the resonator formed by the 50% reflection films 205 having a short resonator length within the half width of the gain spectrum of the semiconductor laser. As a result, mode hopping does not occur in the range of 0 to 100 degrees and the wavelength change due to temperature is 0.01.
A value of nm / ° C was realized.

(Embodiment 5) A fifth embodiment of the present invention will be described with reference to the drawings. 12 and 13 show sectional structures and mounting layouts of the semiconductor laser chip used as the light source. In this structure, first, n-Zn _0.86 Mg is formed on the n-GaAs substrate 101.
_0.14 S _0.1 Se _0.9 cladding layer 501, multiple quantum well active layer 502, p-Zn _0.86 Mg _0.14 S _0.1 Se _0.9 cladding layer 503, p-Zn _0.86 Mg _0.14 Se strain absorption layer 504,
p-Zn _0.86 Mg _0.14 S _0.1 Se _0.9 Second cladding layer 50
5, p-ZnSe contact layer 506, ZnSe / Zn
The Te superlattice contact layer 507 and the ZnTe contact layer 508 were sequentially crystal-grown. Multiple quantum well active layer 502
Is formed by alternately stacking 6 Zn _0.7 Cd _0.3 Se well layers (5 nm) and 7 ZnS _0.1 Se _0.9 barrier layers (3 nm). Next, two stripes of SiO _{2 are} formed on this structure by using a thermal CVD method and a photolithographic technique.
A mask is formed in the shape of a partially bent stripe 511 as shown in FIG. The curved stripes have an interval of about 50 μm in most of the elements, but have an interval of about 5 μm at the laser emission end. Using this SiO ₂ as a mask, the ZnTe contact layer 508 passes through p-Zn.
_0.86 Mg _0.14 S _0.1 Se _0.9 The second clad layer 505 is etched by leaving the clad layer in the middle up to about 0.5 μm, the photoresist is removed, and the remaining SiO ₂ is used as a mask to further etch the p-ZnSe cap layer 506.

Next, after removing the SiO ₂ mask,
SiN film 509 (film thickness 1.2μ by plasma CVD method)
m) was deposited. Since the deposited SiN film 509 is thin at the shoulder portion of the stripe, the ZnTe layer at the shoulder portion can be exposed by lightly etching with a hydrofluoric acid-based etching solution. When a photoresist is applied here to a thickness of about 1 μm and etched back by oxygen plasma, the surface of SiN deposited on the stripe is exposed. Here, if SiN is etched by CF ₄ plasma, only the tips of the stripes can be exposed. Au on the surface of the wafer
The electrode 109 containing as a main component was formed, the GaAs substrate was etched to about 100 μm by mechanical polishing and chemical etching, and the electrode 110 containing Au as a main component was also formed on the GaAs substrate side. A gap 510 is provided on the surface electrode 109 so that each stripe can be driven independently.

On the front surface of the laser chip manufactured as described above, a front reflection film 112 having a reflectance of 9% with respect to laser light is formed.
A rear reflection film 113 having a reflectance of 50% with respect to the laser light is provided on the rear surface of the Si submount 1 using In-based solder.
It was adhered to 14 as shown in FIG. On the rear surface side of the laser chip, a reflecting plate 512 having a thickness of about 30 μm is attached in parallel with the end surface of the semiconductor laser with an interval of about 100 μm. The reflector is a p-GaAs substrate 51 with a thickness of about 100 μm.
3, a high-reflection film 202 formed by stacking Si ₃ N ₄ and SiO ₂ on top of it, a phase-controlling SiO ₂ film 203, S
50% formed by laminating i ₃ N ₄ and SiO ₂
It is composed of a reflective film 205. A Zn diffusion layer 514 is provided on the p-GaAs substrate 513 so as to correspond to the light emission position of the semiconductor laser, and also has a function of monitoring the light output of each laser.

When the semiconductor laser having the above structure is oscillated, a double external resonator mode formed by reflection on the front surface and the rear surface of the groove is stacked on the longitudinal mode of the semiconductor laser itself. The two external resonator modes and the external resonator mode in which they are combined are as shown in FIG. 4 as in the first embodiment. As shown in the figure, the width of each mode of the composite external resonator mode is defined by the resonator formed by the high reflection film 203 and the rear surface reflection film 113 of the semiconductor laser, and the mode interval to another mode of the same intensity is Since the 50% reflective film 205 is defined by the external resonator mode formed by the high reflective film 203, a wide mode interval and a narrow spectral width can both be achieved. In order to obtain good laser characteristics, it is necessary to control the resonance wavelength of the optical resonator formed by the 50% emission film 205 having a short resonator length and the high reflection film 203 within the half width of the emission spectrum of the semiconductor laser. was there. This allows
In the range of 0 to 100 degrees, mode hopping did not occur, and the wavelength change with temperature was 0.01 nm / ° C.

[0030]

According to the present invention, the temperature dependence of the wavelength of the semiconductor laser can be reduced and a wide stable temperature range can be achieved at the same time.
By compensating the temperature characteristics of the semiconductor laser with changes in the coupling efficiency with the external resonator, it is possible to realize an element whose characteristics do not depend on temperature. Furthermore, by applying the present invention to an array element, an array element without crosstalk can be realized.

[Brief description of drawings]

FIG. 1 is a plan view of a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a mounting top view of the semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a sectional view of the Si submount according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a resonator spectrum gain spectrum of the present invention.

FIG. 5 is a plan view of a semiconductor laser according to a second embodiment of the present invention.

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

FIG. 7 is a sectional view of a reflector according to a second embodiment of the present invention.

FIG. 8 is a plan view of a semiconductor laser according to a third embodiment of the present invention.

FIG. 9 is a mounting top view of a semiconductor laser according to a third embodiment of the present invention.

FIG. 10 is a plan view of a semiconductor laser according to a fourth embodiment of the present invention.

FIG. 11 is a top view of a semiconductor laser according to a fourth embodiment of the present invention.

FIG. 12 is a plan view of a semiconductor laser according to a fifth embodiment of the present invention.

FIG. 13 is a mounting top view of a semiconductor laser according to a fifth embodiment of the present invention.

FIG. 14 is a conventional wavelength-stabilized laser.

FIG. 15 is a cross-sectional view showing a conventional external cavity laser light source.

FIG. 16 is an explanatory diagram showing a laser printer to which the present invention is applied.

[Explanation of symbols]

101 ... n-GaAs substrate, 102 ... n- (Al _0.5 Ga
_{0.5) 0.5} In _0.5 P cladding layer, 103 ... MQW active _{layer, 104 ... p- (Al 0.5 Ga} 0.5) 0.5 In 0. 5 P cladding layer, 105 ... p-GaAs contact layer, 106 ...
n-GaAs block layer, 107 ... p-In _0.5 Ga _0.5
P, 108 ... P-GaAs buried layer, 109 ... Surface electrode,
110 ... Back electrode, 111 ... Laser chip, 112 ... Front reflective film, 113 ... Rear reflective film, 114 ... Si submount, 115 ... Glass plate, 116 ... Dielectric multilayer film with reflectance of 50%, 117 ... Reflectance of 100 % Dielectric multilayer film, 1
18 ... Protrusion, 119 ... Si wafer, 120 ... SiO
₂ film, 121 ... Resonator mode, 122 ... Resonator mode,
123 ... Gain spectrum of semiconductor laser at room temperature (25 degrees), 124 ... Maximum value of gain spectrum of semiconductor laser, 201 ... Reflector, 202 ... Glass substrate, 203 ... High reflection film, 204 ... SiO ₂ film, 205 ... 50% reflective film,
206 ... Example _{3,301 ... n-Al 0.5 Ga 0.5} As cladding layer, 302 ... MQW active layer, 303 ... p-
Al _0.5 Ga _0.5 As clad layer, 304 ... Recessed, 305
... Glass plate, 401 ... p-SiC (6H) substrate, 402
... p-Al _0.2 Ga _0.8 N cladding layer, 403 ... MQW active _{layer, 404 ... n-Al 0.2 Ga} 0. 8 N cladding layer, 405 ... n-GaN contact layer, 406 ... n-S
iC layer, 407 ... Ridge, 501 ... n-Zn _0.86 Mg
_0.14 S _0.1 Se _0.9 clad layer, 502 ... Multiple quantum well active layer, 503 ... p-Zn _0.86 Mg _0.14 S _0.1 Se _0.9 clad layer, 504 ... p-Zn _0.86 Mg _0.14 Se strain absorption layer,
505 ... p-Zn _0.86 Mg _0.14 S _0.1 Se _0.9 second cladding layer, 506 ... p-ZnSe contact layer, 507 ... Z
nSe / ZnTe superlattice contact layer, 508 ... ZnT
e contact layer, 509 ... SiN film, 510 ... gap, 5
11 ... Bent stripes, 512 ... Reflector, 513 ...
p-GaAs substrate, 514 ... Zn diffusion layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Saito 2-6-2 Otemachi, Chiyoda-ku, Tokyo Nititsu Koki Co., Ltd.

Claims (7)

[Claims] 1. A semiconductor structure having a function of generating an optical gain when energized and a semiconductor laser having an optical resonator structure formed of a reflecting surface sandwiching the structure, facing at least one reflecting surface. A laser light source comprising a reflector having at least two reflecting surfaces. 2. The laser light source according to claim 1, wherein the resonance wavelength of the optical resonator having the shortest optical path length is longer than the peak wavelength of the gain spectrum at the assumed maximum operating temperature of the semiconductor structure. Laser light source set to. 3. A laser light source according to claim 1, wherein said semiconductor laser has a plurality of optical resonator structures which can be individually driven on the same chip. 4. The control of the resonance wavelength according to any one of claims 1 to 3 is performed by controlling the distance between the semiconductor laser and the reflector by means of a protrusion formed on a base body. 5. The control of the resonance wavelength according to any one of claims 1 to 3 is performed by controlling the thickness of the reflector. 6. The control of the resonance wavelength according to any one of claims 1 to 3 is performed by providing a recess in the reflector provided in close contact with the reflecting surface of the semiconductor laser and controlling the thickness of the recess. thing. 7. A laser light application device using the laser light source according to any one of claims 1 to 6.