JPH0974251A - Semiconductor laser and optical printing device using that - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser, which can conduct stably a control of a printing dot diameter based on a light output modulation when an optical printing is carried out. SOLUTION: A semiconductor laser has two layers of semiconductor layers, which have conductivity types different from each other, an active layer, which is held between the two layers of these semiconductor layers and consists of a semiconductor layer having a forbidden band width narrower than that of the two layers of these semiconductor layers, and a waveguide for confining light within the plane parallel to the active layer and the waveguide is constituted of a narrow region 113 and a wide region 114 for controlling the form of a beam on a laser end face. A region of the intermediate width between the width of the region 113 and the width of the region 114 may be provided between the regions 113 and 114.

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 a light source for a laser printer or the like and an optical printing device using the same.

[0002]

2. Description of the Related Art As a method of increasing the resolution of a laser printer, the characteristic of a photoconductor that only colors a portion irradiated with light having an intensity exceeding the threshold of photosensitivity is utilized to obtain the light shown in FIG. A method has been proposed in which a printed dot diameter is controlled by using a semiconductor laser having an intensity distribution and changing its output.

[0003] In addition, the ones related to this type of technology are
SID 90 digest 280 pages (19
90) (SID 90 DIGEST 280p) and the like.

[0004]

In the above prior art, since the relationship between the print dot diameter and the light output is complicated and it is necessary to record all the light output-dot diameter correlation data, the dot diameter control with a large memory capacity is required. There was a problem that it was necessary to provide a circuit. Further, since the gradient of the intensity distribution is gentle in the vicinity of the apex of the light intensity distribution or in the area at the skirt of the distribution, there is a problem that the variation in the print dot diameter is large and the control of image quality becomes difficult.

A first object of the present invention is to achieve the following in optical printing:
It is an object of the present invention to provide a semiconductor laser device capable of stably controlling a print dot diameter by modulating light output.

A second object of the present invention is to provide an optical printing apparatus using such a semiconductor laser device.

[0007]

In order to achieve the above first object, a semiconductor laser device of the present invention comprises two semiconductor layers having different conductivity types, and a semiconductor layer sandwiched between the two semiconductor layers. It has an active layer consisting of a semiconductor layer having a band gap narrower than that of the layer, and a waveguide for confining light in a plane parallel to the active layer. The waveguide is configured so as to change substantially linearly in the lateral direction.

As an example for making the light density of the beam shape as described above, the waveguide may be composed of at least two kinds of regions having different widths. In addition, it is preferable that a part of the wider region of the waveguide having different widths is configured such that a part thereof has a different amount of current injection from the other part. When there are three or more types of regions having different widths, the region may be wider than the narrowest region, that is, the widest region or the second widest region may be configured as described above.

Further, in order to achieve the first object,
The semiconductor laser device of the present invention includes two semiconductor layers having different conductivity types, an active layer composed of semiconductor layers sandwiched between the semiconductor layers and having a band gap narrower than the two semiconductor layers, and an active layer. When a photoconductor is irradiated with a semiconductor laser device having a waveguide for confining light in parallel planes, the region of the photoconductor that exceeds the threshold of photosensitivity changes substantially in proportion to the light output. As described above, the waveguide is configured.

The area exceeding the photosensitivity threshold of the photoreceptor is
As an example for changing the wavelength substantially in proportion to the optical output, the waveguide may be formed from at least two types of regions having different widths. In addition, it is preferable that a part of the wider region of the waveguide having different widths is configured such that a part thereof has a different amount of current injection from the other part. When there are three or more areas with different widths, if the area is wider than the narrowest area, that is, even the widest area,
The second largest area may be configured as described above.

Furthermore, in order to achieve the above first object, the semiconductor laser device of the present invention is provided with a semiconductor laser device having different conductivity types.
A semiconductor layer, a semiconductor layer sandwiched between the semiconductor layers, an active layer having a forbidden band width narrower than that of the two semiconductor layers, and a waveguide for confining light in a plane parallel to the active layer. , To control the beam shape at the laser facet,
The waveguide is formed of at least two types of regions having different widths.

In this semiconductor laser device, it is preferable that a part of the wider region of the waveguide having different widths has a current injection amount different from that of the other part.

Furthermore, in order to achieve the above first object, the semiconductor laser device of the present invention is provided with two semiconductor layers of different conductivity types provided on a semiconductor substrate and between the two semiconductor layers. And an active layer made of a semiconductor layer having a narrower band gap than the two semiconductor layers and a waveguide for confining light in a plane parallel to the active layer. A waveguide having a wide width is disposed in the vicinity of the end face of the semiconductor laser, and the length L of the wide waveguide and the 0th-order transverse mode propagating in the wide waveguide are provided. Propagation constant k ₀ of the second-order transverse mode,
k ₂ is π / 6 <L × (k ₀ −k ₂ ) <5π / 6 (however,
(k ₀ , k ₂ , L are assumed to be real numbers).

It is preferable that some regions of the waveguide having a wide width have different current injection amounts and current injection densities from other regions.

Further, in order to achieve the first object, the semiconductor laser device of the present invention is provided with two semiconductor layers of different conductivity types provided on a semiconductor substrate and between the two semiconductor layers. And an active layer made of a semiconductor layer having a narrower band gap than the two semiconductor layers and a waveguide for confining light in a plane parallel to the active layer. A waveguide having a wide width is disposed in the vicinity of the end face of the semiconductor laser, and the length L of the wide waveguide and the 0th-order transverse mode propagating in the wide waveguide are provided. Propagation constant k ₀ of the second-order transverse mode,
k ₂ satisfies the relation of 5π / 6 ≦ L × (k ₀ −k ₂ ) <7π / 6 (where k ₀ , k ₂ , and L are real numbers).

It is preferable that some regions of the waveguide having a wide width have different current injection amounts and current injection densities from other regions.

Further, in order to achieve the first object, the semiconductor laser device of the present invention is provided with two semiconductor layers of different conductivity types provided on a semiconductor substrate and between the two semiconductor layers. And an active layer composed of a semiconductor layer having a band gap narrower than that of the two semiconductor layers, and a waveguide for confining light in a plane parallel to the active layer. The lengths of the other waveguides, excluding the narrowest width of the waveguide, are composed of regions of different widths.
The total of the phase differences of the light is determined to be π / 6 to 5π / 6 by propagating the 0th-order transverse mode and the 2nd-order transverse mode that propagate in the other waveguides, respectively.

Further, in order to achieve the first object, the semiconductor laser device of the present invention is provided with two semiconductor layers of different conductivity types provided on a semiconductor substrate and between the two semiconductor layers. And an active layer composed of a semiconductor layer having a band gap narrower than that of the two semiconductor layers, and a waveguide for confining light in a plane parallel to the active layer. The lengths of the other waveguides, excluding the narrowest width of the waveguide, are composed of regions of different widths.
The sum of the phase differences of the light is determined to be 5π / 6 to 7π / 6 by propagating the 0th-order transverse mode and the 2nd-order transverse mode respectively propagating through the other waveguides.

It is preferable that some regions of the other waveguides of these semiconductor laser devices have different current injection amounts and current injection densities from the other regions. Further, it is preferable that the other waveguide is arranged near the end face of the semiconductor laser.

Further, these semiconductor laser devices may have a structure in which a plurality of semiconductor laser devices are arranged side by side in the same direction on the same substrate. Such a structure is suitable for use in an optical printing device.

In order to achieve the second object,
The optical printing apparatus of the present invention includes a photoconductor used for optical printing,
Any one of the above semiconductor laser devices for optically recording on the photosensitive member, means for changing the position of the photosensitive member irradiated by the laser, and control means for controlling these are provided. It is a thing.

The waveguides of the semiconductor laser device have different widths.
If it is formed by two waveguides, a higher-order transverse mode component is generated at the junction of the waveguides. While propagating in the waveguide, these higher-order modes gradually shift in phase due to the difference in the wave number from the fundamental mode, and if the length of the waveguide is selected appropriately, it can be approximated by the Gaussian distribution obtained with ordinary semiconductor lasers. It is possible to obtain a beam shape that is completely different from the light intensity distribution. Further, for example, it is also possible to form a structure having two current injection regions parallel to a part of the waveguide of the semiconductor laser device and obtain the distribution of the refractive index generated by current injection in this part. is there.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> A first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a sectional structural view of the manufactured semiconductor laser device, and FIG. 1 is a plan view during the manufacturing thereof. First, n-G
On the aAs substrate 101, n-Al _0.5 Ga _0.5 As cladding layer 102, multiple quantum well active layer 103, p-Al _0.5
The Ga _0.5 As clad layer 104 and the p-GaAs contact layer 105 were sequentially grown. The multiple quantum well active layer 103 was formed by alternately stacking three layers of a GaAs well layer 106 (7 nm) and four layers of an Al _0.3 Ga _0.7 As barrier layer 107 (5 nm). The p-Al _0.5 Ga _0.5 As cladding layer 104 had a thickness of 1.5 μm, and the p-GaAs contact layer 105 had a thickness of 0.3 μm.

Next, thermal CVD (chemical vapor deposition) method and photolithographic technique are applied to this structure to form p-GaAs.
A stripe-shaped SiO ₂ film 11 is formed on the contact layer 105.
5 is formed into a shape as shown in FIG. Using this SiO ₂ film as a mask, the p-GaAs contact layer 105 and the p-Al _0.5 Ga _0.5 As clad layer 104 are about 0.2 μm.
After etching with leaving m, the n-GaAs block layer 108 was selectively grown in the region without the SiO ₂ film 115 by the metal organic chemical vapor deposition method. In order to reduce the series resistance of the device, after removing the SiO ₂ film 115, p-Al _0.5 Ga
_0.5 As buried layer 109 and p-GaAs cap layer 11
Formed 0.

Next, an electrode 111 containing Au as the main component is formed on the surface of the wafer, the n-GaAs substrate is etched to about 100 μm by mechanical polishing and chemical etching, and Au is also the main component on the substrate side. The electrode 112 was formed. Such a semiconductor wafer was cleaved into bars at intervals of about 600 μm. The semiconductor laser continuously oscillated at an oscillation wavelength of about 780 nm.

The stripe-shaped waveguide forming the laser resonator is composed of a region having a width of about 4 μm (corresponding to the region 113 in FIG. 1) and a region having a width of about 6 μm (corresponding to the region 114 in FIG. 1). . The length of the region with a width of 6 μm is such that the phase difference between the fundamental mode and the higher-order modes is π / 2 at the laser end face.
To be about 54 μm. When the narrow striped waveguide and the wide striped waveguide are thus formed, the width of the latter is preferably 1.1 to 1.9 times the width of the former, and 1.4 to 1.6. It is more preferable to double the number.

When stripes having different widths are connected to each other in this manner, when the light of the fundamental transverse mode in this stripe is incident on the wide stripe from the narrow stripe, the energy of the incident light is a plurality of stripes of the wide stripe. It is distributed in the horizontal mode. The energy distribution ratio is determined by the spatial overlap of the narrow stripe fundamental transverse mode and the wide stripe transverse mode. In order to obtain a beam having the above-mentioned shape by connecting stripes of two kinds of width, it was appropriate to set the ratio of the widths of both stripes in the range of 1.1 times to 1.9 times. When the stripe width ratio exceeds 1.9 times, the energy of the light traveling from the narrow stripe to the wide stripe is mainly distributed to the second or more transverse modes in the wide stripe and the shape of the output beam is increased. Side lobes were generated at the spot and the spot shape was disturbed. Further, if the stripe width ratio is less than 1.1 times, the energy distributed to the secondary transverse modes of the wide stripe is too small and a sufficient effect cannot be obtained.

As described above, the energy of light incident on a wide stripe is distributed to a plurality of transverse modes. However, in the vicinity of the boundary surface of both stripes, the shape of the beam in which these modes are superposed is from a narrow stripe. It matches the shape of the incident beam. However, since each transverse mode in the wide stripe has a different propagation constant depending on its order, a phase shift occurs between the transverse modes as the beam travels through the wide waveguide. When the phase difference between the fundamental mode and the secondary mode satisfies L × (k ₀ −k ₂ ) = π / 2, the beam shape is close to a desired triangle. Also,
In the range of π / 6 <L × (k ₀ −k ₂ ) <5π / 6, a substantially effective effect can be obtained. Here, L is the length of the wide stripe, and k ₀ and k ₂ are the propagation constants of the fundamental transverse mode and the secondary transverse mode in this stripe, and in this embodiment, k ₀ = 3.3295 × 2π / λ. , K ₂ = 3.3259
It was × 2π / λ.

The details of the method of calculating the propagation constant are omitted here, but for example, H.264. C. Caseyand M.C. B. P
by anish "HETERO STRUCTURE L
ASERS "(Academic Press, 197)
8) pp. It can be calculated using the method for obtaining the effective refractive index of the slab waveguide described in Nos. 31 to 54. First, the slab waveguide model is applied to the laminated structure inside and outside the stripe to obtain the effective refractive index of each laminated structure, and then the same effective method is used as the refractive index of the new slab waveguide. If applied, the effective refractive index n of the waveguide can be obtained from the sectional structure of the laser. Propagation constant k is k = 2
πn / λ (where λ is the wavelength of light in vacuum). Here, when the order of the transverse mode of light is different, the effective refractive index is also different, so that each transverse mode has a different propagation constant. Note that 5π / 6 ≦ L × (k ₀ −k ₂ ) <7π
In the range of / 6, that is, in the vicinity of L = 108 μm, the superiority of the beam shape is lost, but the beam divergence becomes maximum,
It had the advantage of improving the light output. Due to the periodicity of trigonometric functions, the phase of the light described above is the phase 2N ± θ.
Needless to say, (N is an arbitrary integer).

FIG. 3 is a structural example of an optical system of a laser printer using the semiconductor laser device of the present invention. The laser beam emitted from the semiconductor laser device 116 passes through the collimator lens 117, the light amount adjustment filter 118, the beam splitter 120, and the cylindrical lens 119,
The light enters the polygon mirror 122 of the optical deflector, and then
It is reflected and deflected by the rotation of the polygon mirror 122. The cylindrical lens 119 converges the laser beam on a line perpendicular to the rotation axis on the mirror surface in order to correct the scanning position shift due to the parallelism error of the polygon mirror. Further, the laser beam is converged by the scanning lens system 123 on the scanning surface covered with the photosensitive material 124, and repeatedly scans the scanning position 125 at a constant speed.
The scanning surface is moving at a constant speed in a direction perpendicular to the beam scanning.

The photodetector 126 is for detecting the start position of the scanning beam, and this detection signal is sent to the control unit 128 as a synchronization signal 127. Further, the light amount detection sensor 130 detects the signal from the beam splitter 120 via the condenser lens 121, and sends the light amount detection signal 131 to the control unit 128. The control unit 128 controls these based on the image signal 132. Further, the laser drive system 129 drives the semiconductor laser 116 based on the control output of the control unit 128. The control of the light output by the control unit 128 corresponding to such a beam diameter is easily performed by, for example, an analog integrated circuit that sets the light output in proportion to the discharge cycle of the charging / discharging circuit that is a combination of a capacitor, a resistor and a flip-flop circuit. It was realized.

This semiconductor laser device has a light output of 4 mW and 6 m.
FIG. 4 shows the distribution of light intensity on the photosensitive surface when driven at W and 8 mW. Since the photosensitivity threshold of the photoconductor is the value shown by the broken line in the figure, the printed dot size is a simple function of W = 2W ₀ (1-P ₀ / P) with respect to changes in the light output ( Here, since W ₀ is the half-value width of the dot, P ₀ is the threshold sensitivity, and P is the peak value of the light intensity distribution of the laser beam), smooth printing corresponding to the light output can be obtained with good reproducibility. It was

<Second Embodiment> A second embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a sectional structural view of the manufactured semiconductor laser device, and FIG. 5 is a plan view during the manufacturing thereof.
FIG. 6A shows a cross-sectional structure diagram at a position corresponding to line aa in FIG.
FIG. 6B shows a sectional structural view of a position corresponding to the line bb. First, on the n-GaAs substrate 101, n-
(Al _0.5 Ga _0.5 ) _0.5 In _0.5 P cladding layer 201, multiple quantum well active layer 202, p- (Al _0.5 Ga _0.5 ) _0.5
The In _0.5 P clad layer 203 and the p-GaAs contact layer 105 were sequentially crystal-grown. Multiple quantum well active layer 2
02 is three layers of Ga _0.5 In _0.5 P well layer 204 (7 nm) and (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layer 205.
It is formed by alternately stacking four layers (5 nm).

Next, as shown in FIG. 5, heat C is applied to this structure.
A VD method and a photolithographic technique are used to form a composite mask of a stripe-shaped photoresist mask 206 and a SiO ₂ mask 211. A method of manufacturing such a composite mask will be described with reference to FIG. FIG. 7A shows a desired pattern 214 and the groove 2 around it in the portion of FIG. 6A (in which the p-GaAs contact layer 105 described above is formed).
A state is shown in which a SiO ₂ mask 211 having 15 is formed, and then a photoresist mask 206 is provided so as to cover a desired pattern 214 and a groove 215. Next, as shown in FIG. 7B, the SiO ₂ outside the groove 215 is etched to leave only the desired pattern 214 of SiO ₂ covered with the photoresist. As shown in FIG. 5, the SiO ₂ mask 211 is formed in the normal width region and the wide width region 208 to be thinner than the photoresist mask 206 by the amount corresponding to the groove 215. The intermediate width region 207 is formed on a part of the halftone regions 210 on both sides (SiO ₂ mask 211 shown in the enlarged portion of FIG. 5). In addition,
There are many SiO ₂ masks 211 in the halftone region 210 as shown in the enlarged portion of FIG.
Since it becomes complicated, only three are shown on the left and right.

By this method, the shape of the waveguide of the semiconductor laser and the shape of current injection can be set almost independently. The photoresist mask 206 has a shape in which a stripe having a normal width (about 4 μm) that occupies most of the element spreads in two steps near the end face.

Returning to FIG. 6, the description will be continued. Using this photoresist mask 206, the p-GaAs contact layer 1
05 and p- (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P clad layer 203 are etched leaving about 0.2 μm. Next, the photoresist is removed, and n- is formed by metalorganic vapor phase epitaxy.
The GaAs block layer 108 was selectively grown in a region without the SiO ₂ mask 211.

Next, in order to reduce the series resistance of the element, Si
After removing the O ₂ mask 211, p-Al _0.5 Ga _0.5 A
The s-buried layer 109 and the p-GaAs cap layer 110 were formed. Next, the electrode 111 containing Au as a main component was formed on the surface of the wafer.

At this time, the surface electrode 111 is provided with a region 212 from which the electrode has been removed by the usual lift-off method, and there is no electrode on the waveguide of the semiconductor laser, so that SiO ₂ used for the lift-off is used. Only the mask 213 remains. As a result, it was possible to prevent the diffusion of the metal element into the semiconductor and the generation of stress due to the breakage of the electrodes and the like, and to realize a highly reliable element. This electrode structure is generally effective in a ridge-embedded semiconductor laser, but it is particularly effective in this embodiment in which complicated unevenness is generated on the waveguide surface.

As a countermeasure against the occurrence of such irregularities, the p-Al _0.5 Ga _0.5 As burying layer 109 and the p-GaA are used.
It was also possible to perform crystal growth of the s cap layer 110 by a liquid layer growth method and form the surface substantially flat as shown in FIG.

Ga by mechanical polishing and chemical etching
After etching the As substrate to about 100 μm, GaAs
The electrode 112 containing Au as a main component was also formed on the substrate side.
Such a semiconductor wafer was cleaved at an interval of about 600 μm in a bar shape to obtain a semiconductor laser device.

The stripe-shaped waveguide forming the laser resonator of this semiconductor laser device has a width of about 4 μm (see FIG. 5).
(Corresponding to the region 206 in FIG. 5), an intermediate width region having a width of about 7 μm (corresponding to the region 207 in FIG. 5), and a wide region having a width of about 20 μm (corresponding to the region 208 in FIG. 5). The length of the wide width region was about 30 μm, and the length of the intermediate width region was about 70 μm so that the phase of the fundamental mode and the higher mode was π / 2 at the laser end face. With this structure, it is possible to obtain a light intensity distribution having a more triangular shape.

When there are two or more stripe widths, it is difficult to define the optimum stripe width and length by a simple relationship, but the shape of the light guided to each stripe is linearly coupled in the transverse mode. The energy of light distributed to each transverse mode is calculated based on the spatial coupling of the transverse mode of one stripe and the transverse mode of the other stripe at the point where the width of the stripe changes, and each transverse mode is calculated. The shape of the spot at the laser emission position can be obtained by repeating the operation of propagating the stripe with a unique propagation constant. In this case, in order to obtain a good beam shape, the energy of the higher-order transverse modes of the third order or higher is 10% or less of the total light energy in the stripes on the end face portion.
It is necessary that the energy of the next transverse mode is in the range of 10% to 40% of the total light energy, and the phase difference between the 0th transverse mode and the second transverse mode is in the range of π / 6 to 7π / 6. , Π / 6 to 5π / 6 is more preferable.

In a structure having stripes having a plurality of widths, if the current injection into the stripes is non-uniform, not only the beam shape becomes triangular, but also the function of changing the width of the triangle can be added. This is because, in the semiconductor laser, the refractive index of the active layer is reduced by current injection, so that current injection into only the peripheral portion of the stripe can reduce the secondary transverse mode without significantly changing the propagation constant wavenumber of the fundamental mode. Even if the stripe length remains constant, the phase difference between the modes passing through this stripe can be changed. Increasing the current injection increases the light output, but since the beam expanding effect due to the change in the refractive index as described above also occurs, not only the height but also the width of the light intensity distribution increases as the injection current increases.

This semiconductor laser device has a light output of 4 mW and 6 m.
FIG. 8 shows the distribution of light intensity on the photosensitive surface when driven at W and 8 mW. Since the photosensitivity threshold of the photoconductor is the value shown by the broken line in the figure, the printed dot size is a simple function of W = 2W ₀ (1-P ₀ / P) with respect to changes in the light output ( Here, W ₀ is the half-value width of the dot, P ₀ is the threshold sensitivity, and P is the peak value of the light intensity distribution of the laser beam). Therefore, it corresponds to the light output as in the case of the first embodiment. Smooth printing was obtained with good reproducibility.

The non-conducting region may be provided not in the intermediate width region 207 but in the wide width region 208.

<Third Embodiment> A third embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a cross-sectional structural view of the semiconductor laser device manufactured in this example, and FIG. 10 is a plan view during the manufacturing thereof. FIG. 11 shows a sectional structural view of a position corresponding to line aa in FIG. First, the n-GaAs substrate 10
An n-Al _0.5 Ga _0.5 As clad layer 102, a multiple quantum well active layer 103, a p-Al _0.5 Ga _0.5 As clad layer 104, and a p-GaAs contact layer 105 were sequentially grown on the No. 1 layer. The multiple quantum well active layer 103 is made of GaA.
Three layers of s-well layer 106 (7 nm) and Al _0.3 Ga _0.7 A
The four barrier layers 107 (5 nm) are alternately laminated.

Next, by using a thermal CVD method and a photolithographic technique for this structure, a stripe-shaped SiO ₂ film is formed on the p-GaAs contact layer 105 as shown in FIG. 10 (region 206 ′, wide region 208). Corresponding shape). Using this SiO ₂ film as a mask, the p-GaAs contact layer 105 and the p-Al _0.5 Ga _0.5 As clad layer 104 are etched leaving about 0.3 μm. Further, a lens-shaped non-conducting region 302 is formed on a part of the SiO ₂ film.
In order to provide the film, the SiO ₂ film in this portion is removed. After that, the n-In _0.5 Ga _0.5 P block layer 301 is selectively grown in the region without the SiO ₂ film by the metal organic chemical vapor deposition method. That is, the n-In _0.5 Ga _0.5 P block layer 301
Are formed on the right and left sides of the stripe-shaped SiO ₂ film and on the lens-shaped non-conduction region 302.

In order to reduce the series resistance of the device, after removing the SiO ₂ film, a p-Al _0.5 Ga _0.5 As buried layer 109 and a p-GaAs cap layer 110 were formed. Next, the electrode 111 containing Au as a main component was formed on the surface of the wafer.

At this time, the surface electrode 111 is provided with a region 212 from which the electrode has been removed by using the normal lift-off method, and there is no electrode on the waveguide of the semiconductor laser, and the SiO ₂ used for lift-off is used. Only the mask 213 remains. As a result, it was possible to prevent the diffusion of the metal element into the semiconductor and the generation of stress due to the breakage of the electrodes and the like, and to realize a highly reliable element. This electrode structure is generally effective in a ridge-embedded semiconductor laser, but the effect is particularly great in this embodiment in which complicated unevenness is generated on the waveguide surface.

N− by mechanical polishing and chemical etching
Etching a GaAs substrate to about 100 μm, n-Ga
The electrode 112 containing Au as a main component was also formed on the As substrate side. Such a semiconductor wafer was cleaved at an interval of about 600 μm in a bar shape to obtain a semiconductor laser device.

The stripe-shaped waveguide forming the laser resonator of this semiconductor laser device is constituted by a region 206 'having a width of about 5 μm and a wide region 208 having a width of about 8 μm in FIG. The length of the wide region 208 having a width of 8 μm is such that the propagation constants of the fundamental mode and the secondary mode of this stripe are k.
₀ = 3.3297 × 2π / λ, k ₂ = 3.3273 × 2π
Since it is / λ, it is set to about 89 μm so that the phase difference between the fundamental mode and the higher-order modes becomes π / 2 at the laser end face. Further, a modulation injection region in which the n-In _0.5 Ga _0.5 P block layer 301 is partially provided is provided in the wide region. With this structure, it is possible to obtain a light intensity distribution closer to a triangular shape, and the beam diameter increases as the light output increases due to the effect of the modulation injection region.
A larger change in beam diameter can be obtained.

In the stripe having such a shape, the laser beam propagates toward the end face while expanding, so that astigmatism occurs and the beam is narrowed by the optical system. Such astigmatism could be corrected by forming a convex lens-like refractive index distribution in the stripe near the emitting end face by injecting current.

In this structure, the astigmatism of the laser beam is corrected by providing the concave lens-like modulation injection region as shown in FIG. 10 in the wide region. The printed dot size changes in proportion to the light output, and the change rate of the light intensity near the light sensitivity threshold is large in any use condition, and smooth printing corresponding to the light output is reproducible. Well obtained Moreover, in the case of this laser, the increase or decrease of the optical output due to the current injection is mainly absorbed by the fluctuation of the beam size, and the change in the peak power is small, so the spot diameter can be changed even when performing multicolor printing using multiple charging levels. Variable printing is now possible. Further, the astigmatism is small due to the effect of aberration correction, and it is possible to realize an inexpensive device without the need for optical aberration correction during device assembly.

<Embodiment 4> As a fourth embodiment of the present invention, an example of a semiconductor laser device in which the semiconductor lasers of the above embodiments are arranged in an array will be shown. In the semiconductor laser device shown in FIG. 12, four semiconductor lasers of Example 1 are arranged at intervals of 50 μm, and the shape of the waveguide portion is shown in the figure.

First, on the n-GaAs substrate 101, n-
(Al _0.5 Ga _0.5 ) _0.5 In _0.5 P cladding layer 201, multiple quantum well active layer 202, p- (Al _0.5 Ga _0.5 ) _0.5
The In _0.5 P clad layer 203 and the p-GaAs contact layer 105 were sequentially crystal-grown. Multiple quantum well active layer 2
02 is formed by alternately stacking 3 layers of Ga _0.5 In _0.5 P well layers (7 nm) and 4 layers of (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layers (5 nm).

Next, a stripe-shaped SiO ₂ film is formed in a shape as shown in FIG. 12 on the p-GaAs contact layer 105 by using a thermal CVD method and a photolithographic technique for this structure. The mask shape is such that a stripe having a normal width (about 4 μm) (corresponding to the region 113) occupying most of the element spreads to about 6 μm near the end face (region 114).
Corresponding to). Using this SiO ₂ film as a mask, the p-GaAs contact layer 105 and p- (Al
_0.5 Ga _0.5 ) _0.5 In _0.5 P clad layer 203 to about 0.2
Etching is performed leaving μm. After that, the n-GaAs block layer 108 was selectively grown in the region without the SiO ₂ film by the metal organic chemical vapor deposition method.

In the present embodiment, the p-GaAs contact layer 105 is set to about 2 in order to reduce the thermal resistance of the device.
The thickness is 0 μm. In addition, in this embodiment,
Prior to the growth of the p-Al _0.5 Ga _0.5 As burying layer 109, the optical output monitor region 401 is provided at each waveguide and the end of the waveguide.
Electrode separation SiO ₂ mask 4 for electrically separating the electrodes
02 is provided, and p-Al _0.5 is formed by this mask.
Each region is electrically isolated by the selective growth of the Ga _0.5 As burying layer 109.

Next, in order to reduce the series resistance of the element, SiO
After removing the _two films, the p-GaAs cap layer 110 was formed. Next, the electrode 111 containing Au as a main component was formed on the surface of the wafer.

At this time, the surface electrode 111 is provided with a region (not shown) from which the electrode is removed by using the normal lift-off method, and there is no electrode on the waveguide of the semiconductor laser. SiO ₂ mask 21 shown in FIG.
Similar to No. 3, only the SiO ₂ mask used for lift-off remains. As a result, it was possible to prevent the diffusion of the metal element into the semiconductor and the generation of stress due to the breakage of the electrodes and the like, and to realize a highly reliable element. This electrode structure is generally effective in a ridge-embedded semiconductor laser, but it is particularly effective in the present invention in which complicated unevenness is generated on the waveguide surface.

In this embodiment, the waveguide is the surface electrode 1
It is provided so as to be located approximately 5 μm from the end of 11 (the position from the left end of the electrode 111 in FIG. 12). This is to secure a sufficient area that can be bonded while avoiding the waveguide when bonding the current-carrying gold wire 403 to the electrode.

N− by mechanical polishing and chemical etching
After etching the GaAs substrate to about 100 μm, an electrode 112 containing Au as a main component was also formed on the substrate side. Such a semiconductor wafer was cleaved at an interval of about 600 μm in a bar shape to obtain a semiconductor laser device. This semiconductor laser oscillated at a wavelength of about 680 nm.

The semiconductor laser chip produced as described above was adhered to the SiC heat sink from the back electrode side to assemble the product. When the semiconductor laser is adhered to the heat sink from the back electrode side, there is a problem that the output of the semiconductor laser changes due to heat generation due to energization. In the present embodiment, the resonator length is set to 450 μm based on the result of calculation of the resonator length dependence of the amount of change in optical output due to heat generation.
It was set between m and 1200 μm.

The stripe-shaped waveguide forming the laser resonator of this semiconductor laser device has a region 113 having a width of about 4 μm.
And a region 114 having a width of about 6 μm. Width 6 μm
The propagation constants of the fundamental and second-order modes in the region of are k ₀ =
Since 3.315 × 2π / λ and k ₂ = 3.310 × 2π / λ, the length of this region is about π / 2 so that the phase difference between the fundamental mode and the higher-order modes is π / 2 at the laser facet. It was 34 μm.

This semiconductor laser device has a light output of 4 mW and 6 m.
FIG. 4 shows the distribution of light intensity on the photosensitive surface when driven at W and 8 mW. Since the photosensitivity threshold of the photoconductor is the value shown by the broken line in the figure, the printed dot size is a simple function of W = 2W ₀ (1-P ₀ / P) with respect to changes in the light output ( Here, W ₀ is the half-value width of the dot, P ₀ is the threshold sensitivity, and P is the peak value of the light intensity distribution of the laser beam). Therefore, it corresponds to the light output as in the case of the first embodiment. Smooth printing was obtained with good reproducibility.

In this semiconductor laser, the semiconductor laser oscillates by the current of the main electrode. In the present embodiment, such an arrayed semiconductor laser is further provided with a monitor region 401 for monitoring the optical output with respect to individual waveguides. The monitor region 401 is separated from the other electrodes by the electrode separation SiO ₂ mask 402 as described above, and a voltage lower than the operating voltage of the semiconductor laser or having a polarity opposite to the operating voltage of the semiconductor laser is applied to this portion. Then, the carriers excited in the monitor region 401 by the laser light generate a photocurrent, and the optical output can be monitored by measuring the photocurrent. Since the monitor region 401 is provided for each waveguide, the optical output of each individual waveguide can be obtained. The optical output monitor function is more stable when a voltage of the opposite polarity to the operating voltage of the semiconductor laser is applied to the monitor area, but it is generated by light absorption in the monitor area by applying a voltage of the same polarity as the operating voltage of the semiconductor laser. If this energy is efficiently extracted as electric energy to the outside, a function of electronically cooling this region can be obtained, and it can be used to prevent the end face deterioration of the semiconductor laser.

According to this embodiment, high-definition printing by changing the dot shape and high-speed printing by arraying can be realized at the same time, and high-performance printing of about 10 times printing speed × dot density can be performed except for the semiconductor laser and its driving unit. It could be realized by a laser printer having the same configuration as the conventional one.

When this semiconductor laser device is applied to the laser printer described in the first embodiment, as shown in FIG. 4, each element produces a large variation in beam diameter due to a relatively small change in optical output. There was little crosstalk between them, and good printing was possible at high speed. It goes without saying that the same characteristics can be obtained by arranging the structures of the second and third embodiments in an array.

<Fifth Embodiment> A fifth embodiment of the present invention will be described with reference to the drawings. FIG. 16 is a cross-sectional structural view of the manufactured semiconductor laser device, and FIG. 15 is a plan view during the manufacturing thereof. First, on the n-GaAs tilt substrate 501, n- (Al
_0.7 Ga _0.3 ) _0.5 In _0.5 P clad layer 502, multiple quantum well active layer 503, p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5
P clad layer 504, p-GaAs contact layer 105
Were sequentially crystal-grown. The multiple quantum well active layer 503 is
Three layers of Ga _0.6 In _0.4 P well layer 505 (7 nm),
(Al _0.7 Ga _0.3 ) _0.4 In _0.6 P Barrier layer 506 (5
nm) are alternately laminated.

Next, a thermal CVD method and a photolithography technique are applied to this structure to form a stripe-shaped composite mask of the photoresist mask 206 and the SiO ₂ mask 211 in the shape shown in FIG. Such a composite mask
In the same manner as shown in FIG. 7, first, an SiO ₂ mask having a groove around a desired pattern is formed, and then a photoresist mask 2 is formed so as to cover the desired pattern and the peripheral groove.
After providing 06, the SiO ₂ outside the trench was etched to leave only the desired SiO ₂ pattern 215 covered by the photoresist. Photoresist mask 20
No. 6 has a normal width (about 5 μm) stripe (corresponding to the region 113) that occupies most of the device and is about 8 μm near the end face.
Has a shape (corresponding to the region 114) that spreads out. Using this photoresist mask, the p-GaAs contact layer 105 and p- (Al _0.7 Ga _0.3 ) _0.5 In _{0.5 are formed.}
The P clad layer 504 is etched leaving about 0.2 μm. Next, the photoresist was removed, and the n-GaAs block layer 108 was selectively grown in the region without the SiO ₂ film by the metal organic chemical vapor deposition method. Next, in order to reduce the series resistance of the device, after removing the SiO ₂ film, p-Al _0.5 Ga
_0.5 As buried layer 109 and p-GaAs cap layer 11
Formed 0.

When a substrate deviated from the (100) direction is used as the substrate, the shape of the waveguide becomes asymmetric. Therefore, in this embodiment, the photoresist mask for defining the shape of the waveguide and the SiO ₂ mask for defining the current path are guided. The waveguides are formed so as to be displaced in the direction of correcting the asymmetrical shape. In this embodiment, the photoresist mask 206 and the SiO ₂ mask 2 are used.
The axis shift of 11 was about 1 μm in the direction in which the substrate surface was inclined.

Next, an electrode 111 containing Au as a main component was formed on the surface of the wafer. At this time, the surface electrode 111 has a region 21 from which the electrode is removed by using a normal lift-off method.
2 is provided, there is no electrode on the waveguide of the semiconductor laser, and the SiO ₂ mask 213 used for lift-off is used.
Only remains. This prevents diffusion of metal elements into the semiconductor and generation of stress due to disconnection of the electrodes,
A highly reliable device was realized. This electrode structure is generally effective in a ridge-embedded semiconductor laser, but the effect is particularly great in this embodiment in which complicated unevenness is generated on the waveguide surface.

N− by mechanical polishing and chemical etching
After etching the GaAs substrate to about 100 μm, an electrode 112 containing Au as a main component was also formed on the substrate side. Such a semiconductor wafer was cleaved at an interval of about 600 μm in a bar shape to obtain a semiconductor laser device. This semiconductor laser oscillated at an oscillation wavelength of about 650 nm.

The stripe-shaped waveguide forming the laser resonator of this semiconductor laser device has a region 113 with a width of about 5 μm.
And a region 114 having a width of about 8 μm. Width about 8μ
The length of the region of m is such that the propagation constants of the fundamental mode and the second-order mode in this region are k ₀ = 3.30 × 2π / λ and k ₂ = 3.302.
Since it is 5 × 2π / λ, it is about 65 so that the phase of the fundamental mode and the higher-order mode becomes π / 2 at the laser end face.
μm. With this structure, it is possible to obtain a light intensity distribution having a more triangular shape.

This semiconductor laser device has a light output of 4 mW and 6 m.
FIG. 4 shows the distribution of light intensity on the photosensitive surface when driven at W and 8 mW. Since the photosensitivity threshold of the photoconductor is the value shown by the broken line in the figure, the printed dot size is a simple function of W = 2W ₀ (1-P ₀ / P) with respect to changes in the light output ( Here, W ₀ is the half-value width of the dot, P ₀ is the threshold sensitivity, and P is the peak value of the light intensity distribution of the laser beam). Therefore, it corresponds to the light output as in the case of the first embodiment. Smooth printing was obtained with good reproducibility.

[0075]

According to the present invention, high resolution printing by output modulation can be stably realized in a laser printer. Further, since the change in dot diameter with respect to the change in light amount is large, crosstalk between elements when the elements are arranged in an array can be small, and high-definition printing can be realized at low cost.

[Brief description of drawings]

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

FIG. 2 is a sectional structural view of a semiconductor laser device of a first embodiment of the present invention.

FIG. 3 is a configuration diagram of an example of a laser printer device of the present invention.

FIG. 4 is an intensity distribution diagram of emitted light of the semiconductor laser device according to the first embodiment of the present invention.

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

FIG. 6 is a first sectional structural view of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 7 is a sectional view of the semiconductor laser device according to the second embodiment of the present invention during manufacturing.

FIG. 8 is an intensity distribution diagram of emitted light of the semiconductor laser device according to the second embodiment of the present invention.

FIG. 9 is a cross-sectional structure diagram showing a semiconductor laser device according to a second embodiment of the present invention in another manufacturing method.

FIG. 10 is a plan view of the semiconductor laser device according to the third embodiment of the present invention during manufacturing.

FIG. 11 is a sectional structural view of a semiconductor laser device of a third embodiment of the present invention.

FIG. 12 is a layout view of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 13 is a sectional structural view of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 14 is a diagram showing the relationship between the optical output fluctuation and the cavity length of the semiconductor laser device according to the fourth embodiment of the present invention.

FIG. 15 is a plan view of the semiconductor laser device according to the fifth embodiment of the present invention during manufacture.

FIG. 16 is a sectional structural view of a semiconductor laser device according to a fifth embodiment of the present invention.

FIG. 17 is a light intensity distribution chart of a conventional semiconductor laser device.

[Explanation of symbols]

101 ... n-GaAs substrate 102 ... n-Al _0.5 Ga _0.5 As clad layer 103 ... Multiple quantum well active layer 104 ... p-Al _0.5 Ga _0.5 As clad layer 105 ... p-GaAs contact layer 106 ... GaAs well layer 107 ... Al _0.3 Ga _0.7 As barrier layer 108 ... n-GaAs block layer 109 ... p-Al _0.5 Ga _0.5 As buried layer 110 ... p-GaAs cap layer 111, 112 ... Electrodes 113, 114, 206 ′, 207, 212 ... Region 115 SiO ₂ film 116 Semiconductor laser device 117 Collimating lens 118 Light intensity adjusting filter 119 Cylindrical lens 120 Beam splitter 121 Condensing lens 122 Polygonal mirror 123 Scanning lens system 124 Photosensitive material 125 Scanning position 126 … Photo detector 127… Sync signal 128 ... control unit 129 ... laser drive system 130 ... light amount sensor 131 ... light intensity detection signal 132 ... image signal _{201 ... n- (Al 0.5 Ga 0.5} ) 0.5 In 0.5 P cladding layer 202 ... multiple quantum well active layer 203 ... p- (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P clad layer 204 ... Ga _0.5 In _0.5 P well layer 205 (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P barrier layer 206 ... photoresist mask 208 ... wide area 209, 302 ... non-conducting area 210 ... Halftone area 211, 213 ... SiO ₂ mask 214 ... Pattern 215 ... Groove 301 ... n-In _0.5 Ga _0.5 P block layer 401 ... Optical output monitor area 402 ... SiO ₂ mask 403 ... Conductive gold wire 501 ... n- GaAs inclination substrate _{502 ... n- (Al 0.7 Ga 0.3} ) 0.5 In 0.5 P cladding layer 503 ... multiquantum Door active layer _{504 ... p- (Al 0.7 Ga 0.3} ) 0.5 In 0.5 P cladding layer 505 ... Ga _0.6 In _0. 4P well layers _{506 ... (Al 0.7 Ga 0.3)} 0. 4In 0.6 P barrier layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinya Kobayashi 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Akira Arimoto 1-280, Higashi-Kengokubo, Kokubunji, Tokyo Address Central Research Laboratory, Hitachi, Ltd. (72) Inventor Susumu Saito 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Niritsuko Koki Co., Ltd.

Claims (22)

[Claims] 1. An active layer composed of two semiconductor layers having different conductivity types, a semiconductor layer sandwiched between the semiconductor layers and having a forbidden band width narrower than the two semiconductor layers, and parallel to the active layers. In a semiconductor laser device having a waveguide for confining light in a plane, the optical density of the beam shape at the laser end face changes substantially linearly in the lateral direction from the center line of the waveguide. A semiconductor laser device comprising: 2. The semiconductor laser device according to claim 1, wherein the waveguide is composed of at least two types of regions having mutually different widths. 3. The area of the wider one of the areas having different widths of the waveguide is configured such that a part thereof has a different amount of current injection from the other areas. Semiconductor laser device. 4. An active layer composed of two semiconductor layers having different conductivity types, a semiconductor layer sandwiched between the semiconductor layers and having a forbidden band width narrower than that of the two semiconductor layers, and parallel to the active layers. In a semiconductor laser device having a waveguide for confining light in a plane, when a photoconductor is irradiated with the semiconductor laser device, a region of the photoconductor that exceeds the threshold of photosensitivity is substantially proportional to the optical output. A semiconductor laser device characterized in that the above-mentioned waveguide is configured so as to change as a result. 5. The semiconductor laser device according to claim 4, wherein the waveguide is composed of at least two types of regions having mutually different widths. 6. The area of the wider one of the areas of the waveguide having different widths is configured such that a part thereof has a different amount of current injection from the other areas. Semiconductor laser device. 7. An active layer comprising two semiconductor layers having different conductivity types, a semiconductor layer sandwiched between the semiconductor layers and having a band gap narrower than the two semiconductor layers, and parallel to the active layers. In a semiconductor laser device having a waveguide for confining light in various planes, the waveguide is composed of at least two types of regions having different widths in order to control the beam shape at the laser end face. apparatus. 8. The region of the wider one of the regions having different widths of the waveguide is configured such that a part thereof has a different amount of current injection from the other part. Semiconductor laser device. 9. A two-layer semiconductor layer having different conductivity types provided on a semiconductor substrate, and provided between the two-layer semiconductor layers, and
In a semiconductor laser device having an active layer made of a semiconductor layer having a forbidden band width narrower than the two semiconductor layers and a waveguide for confining light in a plane parallel to the active layer, the waveguide has two types. A waveguide having a wide width, the waveguide having a wide width is located in the vicinity of the end face of the semiconductor laser, and the length L of the wide waveguide and the 0th order propagating in the wide waveguide Propagation constants k ₀ and k _{2 of the} transverse mode and the second-order transverse mode are π / 6 <L × (k ₀ −k ₂ ) <5π / 6.
(However, k ₀ , k ₂ , and L are assumed to be real numbers.) A semiconductor laser device characterized by satisfying the following relationship. 10. Two different conductivity types are provided on a semiconductor substrate.
Of two semiconductor layers, an active layer formed between the two semiconductor layers and having a forbidden band width narrower than that of the two semiconductor layers, and light in a plane parallel to the active layer. In a semiconductor laser device having a waveguide for confining a laser beam, the waveguide is composed of two types of regions having different widths, and the waveguide having the wide width is located near the end face of the semiconductor laser and has the wide width. The propagation constants k ₀ and k _{2 of} the 0th-order transverse mode and the 2nd-order transverse mode propagating in the waveguide having the length L and the wide width of the waveguide are 5π / 6 ≦ L × (k ₀ −k ₂ ) <7π.
/ 6 (where, k ₀ , k ₂ , and L are real numbers). The semiconductor laser device is configured to satisfy the relationship. 11. The semiconductor laser device according to claim 9, wherein a part of the wide waveguide has a current injection amount and a current injection density different from those of the other regions. 12. Two different conductive types are provided on a semiconductor substrate.
Of two semiconductor layers, an active layer formed between the two semiconductor layers and having a forbidden band width narrower than that of the two semiconductor layers, and light in a plane parallel to the active layer. In a semiconductor laser device having a waveguide for confining a waveguide, the waveguide is composed of at least two types of regions having different widths, and the lengths of the other waveguides except the narrowest width waveguide are the same. , 0 respectively propagating through the other waveguides
A semiconductor laser device characterized in that the total of the phase differences of light is set to be π / 6 to 5π / 6 by propagating each of the secondary transverse mode and the secondary transverse mode. 13. Two different conductive types provided on a semiconductor substrate.
Of two semiconductor layers, an active layer formed between the two semiconductor layers and having a forbidden band width narrower than that of the two semiconductor layers, and light in a plane parallel to the active layer. In a semiconductor laser device having a waveguide for confining a waveguide, the waveguide is composed of at least two types of regions having different widths, and the lengths of the other waveguides except the narrowest width waveguide are the same. , 0 respectively propagating through the other waveguides
A semiconductor laser device characterized in that the total of the phase differences of light is determined to be 5π / 6 to 7π / 6 by propagating the second transverse mode and the second transverse mode, respectively. 14. The semiconductor laser device according to claim 9, wherein a part of a region of the other waveguide has a current injection amount and a current injection density different from those of the other region. 15. The semiconductor laser device has electrodes for oscillating laser light upon energization on the front surface side and the back surface side of the substrate, and the electrodes on the front surface side are arranged in regions other than the upper portion of the waveguide. 15. The semiconductor laser device according to claim 9, wherein: 16. The semiconductor laser device according to claim 9, wherein a central axis of current injection into the waveguide is located at a position deviated from the central axis of the waveguide. 17. The semiconductor laser device according to claim 1, wherein a plurality of the semiconductor laser devices are arranged side by side in the same direction on the same substrate. 18. A heat sink is adhered to the back side of the semiconductor substrate, and the length of the waveguide of the semiconductor laser is 450 μm.
18. The semiconductor laser device according to claim 17, wherein the semiconductor laser device is in the range of m to 1200 μm. 19. The semiconductor laser device has electrodes for oscillating laser light upon energization on the front surface side and the back surface side of a substrate, and the central axis of the electrode on the front surface side in the waveguide direction is the waveguide. 19. The semiconductor laser device according to claim 17, wherein the semiconductor laser device is deviated from the central axis. 20. The vicinity of the end of the narrowest waveguide of the waveguides is separated from other regions to form a monitor region for monitoring the optical output of the semiconductor laser device. 20. The semiconductor laser device according to item 17, 18 or 19. 21. The monitor region has electrodes at its upper and lower portions for applying a voltage lower than a voltage applied for causing the semiconductor laser device to emit light or a potential having a reverse polarity. 21. The semiconductor laser device according to claim 20. 22. A photoconductor used for optical printing, a semiconductor laser device for optical recording on the photoconductor, means for changing the position of the photoconductor irradiated by the laser, and controlling these. An optical printing device having a control means for controlling the semiconductor laser device, wherein the semiconductor laser device is the semiconductor laser device according to any one of claims 1 to 21.