JP6052666B2 - Laser printer - Google Patents

Description

  The present invention relates to a laser printer.

  In a general laser printer, a laser beam emitted from a semiconductor laser element is deflected and scanned by a mechanical configuration such as a polygon mirror and irradiated onto a photosensitive drum. In such a laser printer, the printing speed is determined by the speed at which the laser beam is deflected and scanned (such as the rotational speed of the polygon mirror) or the modulation speed at which the laser beam is turned on / off.

  As a laser printer, one in which a laser light source is a multi-emitter semiconductor laser element is known (see, for example, Patent Document 1). In the multi-emitter semiconductor laser element, m light emitting elements are included in one chip. Therefore, when a multi-emitter type semiconductor laser device is used, the printing speed is theoretically m times higher than when a single-emitter type semiconductor laser device including only one light emitting device is used in one chip. It becomes.

JP 2003-315707 A

  However, when the pulse operation for turning on / off the laser beam is repeated at high speed in each of the m light emitting elements included in the multi-emitter type semiconductor laser element, electrical and thermal crosstalk occurs between the light emitting elements. As a result, there is a possibility that the on / off control of the laser beam is not appropriately performed in each light emitting element. Therefore, the pulse operation for turning on and off the laser beam of each light emitting element in the multi-emitter type semiconductor laser element needs to be delayed as compared with the case where each light emitting element is used as the light emitting element of the single emitter type semiconductor laser element. . Therefore, the advantages of the multi-emitter semiconductor laser device cannot be fully utilized, and it is difficult to say that the printing speed is sufficiently increased even when the multi-emitter semiconductor laser device is adopted. It was.

  The present invention has been made in view of such problems, and an object thereof is to provide a laser printer capable of increasing the printing speed.

  The laser printer according to the present invention includes an exposure unit that irradiates a photoconductor with a laser beam to form a latent image on the photoconductor, a moving unit that moves the photoconductor relative to the irradiation position of the laser beam, The exposure means includes at least one of a lower clad layer, an upper clad layer, an active layer interposed between the lower clad layer and the upper clad layer, and an active layer and upper and lower clad layers. A photonic crystal layer interposed between them and a plurality of drive electrodes for supplying a drive current to a plurality of regions of the active layer, and generating a laser beam from the plurality of regions by supplying the drive current The plurality of regions are arranged in parallel to the light emitting end surface of the semiconductor laser device and aligned in the first direction in which the active layer extends, and are generated in the plurality of regions. The emission directions of the laser beam from the light emission end face are different from each other, and the laser beam emitted from the plurality of regions differs between the semiconductor laser element and the photoconductor along a direction parallel to the first direction of the photoconductor. The moving means is arranged so as to irradiate each of the positions, and the moving means moves the photosensitive member relative to the irradiation position of the laser beam emitted from the plurality of regions in a direction orthogonal to the first direction. It is characterized by that.

  In the laser printer according to the present invention, a plurality of laser beams having different emission directions emitted from the semiconductor laser elements are collectively irradiated to different positions along a direction parallel to the first direction on the photosensitive member. Since the laser beam is collectively irradiated, the printing speed can be improved in the semiconductor laser element without repeating the pulse operation at a high speed.

  The emission direction of the laser beam generated in the region adjacent to the arbitrary one region in the first direction is more inclined in the first direction than the emission direction of the laser beam generated in any one region of the plurality of regions. You may do it. In this case, the correspondence between each laser beam and the irradiation position on the photosensitive member is clarified, and printing can be performed reliably and more appropriately.

  The moving unit may move the photoconductor in a direction orthogonal to the first direction every time the photoconductor is irradiated with the laser beam by the exposure unit. The photosensitive member may be a photosensitive drum, and the moving unit may rotate the photosensitive drum in a rotation direction with a direction parallel to the first direction as a rotation axis.

  In the semiconductor laser element, regions corresponding to a plurality of regions of the active layer of the photonic crystal layer have two periodic structures in which arrangement periods of different refractive index portions having different refractive indexes from the surroundings are different from each other. The difference of the reciprocal number of each arrangement period in one periodic structure may differ for every area | region corresponding to the several area | region of the active layer of a photonic crystal layer.

  In the region in the photonic crystal layer corresponding to each drive electrode, the difference in the reciprocal of the arrangement period of the different refractive index portions (exit direction determining factor) is different. The difference value determines the laser beam emission direction. Therefore, since the value of this difference (exiting direction determining factor) is different in both regions, the emitting direction of the laser beam is different in the region corresponding to each drive electrode. Therefore, the laser beam can be output in different directions by switching the supply of the drive current to each drive electrode.

  In the semiconductor laser element, regions corresponding to a plurality of regions of the active layer of the photonic crystal layer have two periodic structures in which arrangement periods of different refractive index portions having different refractive indexes from the surroundings are different from each other. Two or more laser beams forming a predetermined angle with respect to the longitudinal direction of the plurality of drive electrodes when viewed from the thickness direction of the semiconductor laser element in accordance with the difference of the reciprocal of each arrangement period in one periodic structure These laser beams are generated inside the laser element and are set to have a refraction angle of less than 90 degrees with respect to the light emitting end face in these laser beams. At least one of the laser beams toward the light emitting end face is totally reflected on the light emitting end face. The critical angle condition may be set.

  By making the incident angle of the one laser beam inside the laser element to the emission end face be equal to or greater than the total reflection critical angle, the laser beam can be prevented from being output to the outside. Since the refraction angle of the other laser beam is less than 90 degrees, the laser beam can be output to the outside through the light emitting end face. That is, the laser beam can be emitted only in one direction, and the practical application of the semiconductor laser element can be expanded.

  The semiconductor laser element generates a plurality of laser beams, outputs the generated plurality of laser beams in the same direction, and deflects the plurality of laser beams output in the same direction from the oscillation unit in different directions. And an oscillating unit comprising a lower cladding layer, an upper cladding layer, an active layer, and a first photonic crystal layer as a photonic crystal layer. A plurality of drive electrodes, the deflection unit includes a second photonic crystal layer, and the first photonic crystal layer has a different refractive index portion having a refractive index different from that of the surrounding region over a region corresponding to the plurality of regions. The second photonic crystal layer has a periodic structure in which the arrangement periods of the different refractive index portions having different refractive indexes from the surroundings are different for each region corresponding to the plurality of regions. Have Good.

  In the present invention, the first photonic crystal layer has a periodic structure in which the arrangement period of the different refractive index portions is the same over a region corresponding to a plurality of regions. A laser beam is output in the same direction for each drive electrode. Since the second photonic crystal layer has a periodic structure in which the arrangement period of the different refractive index portions is different for each region corresponding to a plurality of regions, the deflection unit outputs the same direction from the oscillation unit. Each laser beam is deflected in different directions and emitted from the light emitting end face.

  In the present invention, in the semiconductor laser element, the oscillation unit and the deflection unit are separated, and the first photonic crystal layer extends over a region corresponding to a plurality of regions, and the arrangement period of the different refractive index portions is the same. Have a periodic structure. For this reason, the oscillation threshold is constant for each laser beam, and stable operation can be realized.

  The second photonic crystal layer causes interference that weakens light transmitted in the same direction as the output direction of the laser beam from the oscillating unit for each region corresponding to the plurality of regions, and the laser beam from the light emitting end surface. Interference that reinforces the light diffracted in the emission direction of the light may be generated. In this case, the deflecting unit can surely deflect each laser beam output in the same direction from the oscillating unit in a different direction and emit it from the light emitting end face.

  According to the present invention, it is possible to provide a laser printer capable of increasing the printing speed.

1 is a schematic diagram of a laser printer according to an embodiment. It is a longitudinal cross-sectional view of a semiconductor laser element. It is a top view of a semiconductor laser element. It is a top view inside an element for explaining a progress state of a laser beam inside a semiconductor laser element. It is a top view of the photonic crystal area | region which has a single periodic structure. It is a top view of the photonic crystal area | region which has a single periodic structure. It is a top view of the photonic crystal area | region which has a some periodic structure. It is a top view of a photonic crystal region group having a plurality of photonic crystal layer regions having a plurality of periodic structures. It is a top view of the photonic crystal layer which has a photonic crystal region group. It is a graph which shows the incident angle and outgoing angle of a laser beam with respect to deflection angle (delta) theta from a reference direction (it depends on the difference of the reciprocal of the period in each photonic crystal region). It is a top view of the different refractive index part (structure) of various shapes. It is a longitudinal cross-sectional view of a semiconductor laser element. It is a top view inside a semiconductor laser element. A vector from the origin O to the point P (βx, βy) in the xy coordinate system. It is a graph which shows the direction of the main light wave in xy coordinate system. It is a top view inside an element explaining the main light wave in active layer 3B. FIG. 4A is a plan view of a diffraction grating layer 4 ′ having a periodic structure, and FIG. 6B is a cross-sectional view in the XZ plane. 5 is a graph showing a relationship between a laser beam emission angle (refraction angle) θ3, a strap angle θ, and a period Λ. It is a chart which shows the data used for a graph. It is sectional drawing of the partial area | region of a semiconductor laser element. It is a top view of a photonic crystal layer. It is a figure which shows the signal processing of a control circuit part. It is a figure for demonstrating the irradiation state of the laser beam in a photosensitive drum. It is a top view of a semiconductor laser element. It is the schematic of the conventional laser printer using a multi-emitter laser light source. 1 is a schematic perspective view of a semiconductor laser device according to an embodiment. It is a figure which shows the cross-sectional structure along the XXVII-XXVII line of the semiconductor laser element shown by FIG. It is a figure which shows the cross-sectional structure along the XXVIII-XXVIII line | wire of the semiconductor laser element shown by FIG. FIG. 27 is a plan view of the semiconductor laser device shown in FIG. 26. It is a top view of a 1st photonic crystal layer. It is a top view which shows the modification of a 1st photonic crystal layer. It is a top view of a 2nd photonic crystal layer. It is the schematic of the laser printer which concerns on the modification of this embodiment.

  Hereinafter, the laser printer according to the embodiment will be described. In addition, the same code | symbol shall be used for the same element and the overlapping description is abbreviate | omitted.

  First, the configuration of the laser printer 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram of a laser printer according to an embodiment.

  As shown in FIG. 1, the laser printer 100 includes a semiconductor laser element 10, a control circuit unit 101, a photosensitive drum 102, a beam shaping lens unit 103, and a power source 104. The laser printer 100 includes an exposure unit that irradiates the photosensitive drum 102 with a laser beam to form a latent image on the photosensitive drum 102, a moving unit that moves the photosensitive drum 102 relative to the irradiation position of the laser beam, Have

  The laser printer 100 performs an exposure operation (the semiconductor laser element 10 irradiates the photosensitive drum 102 with a laser beam), a developing operation (attaching toner to a portion irradiated with the laser beam), and a transfer operation (printing toner on the photosensitive drum 102). (Transfer to paper). The developing operation and transfer operation in the laser printer 100 are the same as those of a known laser printer. Therefore, description of these operations will be omitted, and the configuration related to the exposure operation will be described below.

  The semiconductor laser element 10 forms a latent image on the photosensitive drum 102 by irradiating the photosensitive drum 102 with a laser beam. The semiconductor laser element 10 emits a plurality of laser beams having different emission directions. The laser beam is emitted by the semiconductor laser element 10 based on a signal from the laser element current supply circuit unit 112 of the control circuit unit 101.

  Hereinafter, the configuration of the semiconductor laser element 10 will be described in detail with reference to FIGS.

  FIG. 2 is a longitudinal sectional view of the semiconductor laser element, and FIG. 3 is a plan view of the semiconductor laser element. The semiconductor laser device 10 includes a lower clad layer 2, a lower light guide layer 3 A, an active layer 3 B, an upper light guide layer 3 C, a photonic crystal layer 4, an upper clad layer 5, and a contact layer 6 that are sequentially formed on a semiconductor substrate 1. It has. On the back side of the semiconductor substrate 1, an electrode E <b> 1 is provided on the entire surface, and on the contact layer 6, a plurality of drive electrodes E <b> 2 are provided. In the drawing, five drive electrodes E <b> 2 are simply shown, but actually more drive electrodes E <b> 2 are provided on the contact layer 6.

The surface on the contact layer 6 other than the formation region of the drive electrode E2 is covered with the insulating film SH. The insulating film SH can be formed from, for example, SiN or SiO ₂ .

The materials / thicknesses of these compound semiconductor layers are as follows. Note that an intrinsic semiconductor having an impurity concentration of 10 ¹⁵ / cm ³ or less has no conductivity type. In addition, the density | concentration when an impurity is added is 10 < ¹⁷ > -10 < ²⁰ > / cm < ³ >. Further, the following is an example of the present embodiment. If the configuration includes the active layer 3B and the photonic crystal layer 4, the material system, film thickness, and layer configuration are flexible. The upper light guide layer 3C includes two layers, an upper layer and a lower layer.
Contact layer 6: P-type GaAs / 50 to 500 nm
Upper clad layer 5: P-type AlGaAs (Al _0.4 Ga _0.6 As) /1.0 to 3.0 μm
Photonic crystal layer 4:
Basic layer 4A: GaAs / 50 to 400 nm
Buried layer (different refractive index portion) 4B: AlGaAs (Al _0.4 Ga _0.6 As) / 50 to 400 nm
Upper light guide layer 3C:
Upper layer: GaAs / 10-200 nm
Lower layer: p-type or intrinsic AlGaAs / 10 to 100 nm
Active layer 3B (multiple quantum well structure):
AlGaAs / InGaAs MQW / 10-100nm
Lower light guide layer 3A: AlGaAs / 0 to 300 nm
Lower clad layer 2: N-type AlGaAs / 1.0 to 3.0 μm
・ Semiconductor substrate 1: N-type GaAs / 80 to 350 μm

  For example, AuGe / Au can be used as the material of the electrode E1, and Cr / Au or Ti / Au can be used as the material of the electrode E2.

  The light guide layer can be omitted.

In the manufacturing method in this case, the growth temperature of AlGaAs by the MOCVD method is 500 ° C. to 850 ° C., and 550 to 700 ° C. is adopted in the experiment. (Trimethylgallium) and TEG (triethylgallium), AsH _{3 (} arsine) as the As source, Si ₂ H ₆ (disilane) as the source for the N-type impurity, and DEZn (diethylzinc) as the source for the P-type impurity be able to.

  The plurality of regions R are parallel to the light emitting end surface LES of the semiconductor laser element 10 and are arranged side by side in the direction in which the active layer 3B extends (hereinafter, sometimes referred to as the first direction D1). When a current is passed between the upper and lower electrodes E1, E2, a current flows in a plurality of regions R immediately below one of the electrodes E2, the region R emits light, and the laser beam LB is emitted from the side end surface ( The light is emitted from the light emission end face (LES) at a predetermined emission angle (see FIG. 3). The laser beams LB emitted from the light emission end face LES have different emission directions (emission angles). The emission direction of the laser beam LB is more inclined in the first direction D1 than the laser beam generated in any one region and the laser beam generated in the region adjacent to any one region in the first direction D1. doing.

  The semiconductor laser element 10 and the photosensitive drum 102 are arranged so that the laser beam LB emitted from the light emitting end face LES is irradiated to different positions along the direction parallel to the first direction D1 on the photosensitive drum 102, respectively. Yes. That is, the direction parallel to the first direction D1 is the axial direction (row direction) of the photosensitive drum (see FIG. 1). The semiconductor laser device 10 is set so that the laser beam can be simultaneously irradiated to all the irradiation positions of one row on the photosensitive drum 102. The batch irradiation onto the photosensitive drum 102 by the laser beam emitted from the semiconductor laser element 10 will be described in detail in the description of the control circuit unit 101 described later.

Which laser beam LB is emitted (in which region R the laser beam LB is generated) is determined depending on which of the drive electrodes E2 is supplied with the drive current. Note that which of the drive electrodes E2 is supplied with the drive current is determined based on a signal from the laser element current supply circuit unit 112 of the control circuit unit 101.

  The planar shape of the semiconductor laser element 10 is a rectangle. When an XYZ three-dimensional orthogonal coordinate system is set, the thickness direction is the Z axis, the width direction is the X axis, and the direction perpendicular to the light emitting end surface LES is the Y axis. To do. The direction of the X axis is a direction parallel to the first direction D1 described above. In the XY plane, the extending longitudinal direction of each drive electrode E2 forms an angle φ with respect to a straight line parallel to the Y axis. That is, the longitudinal direction of the drive electrode E2 is inclined with respect to the normal line (Y axis) of the light emitting end face LES of the semiconductor laser element 10 when viewed from the thickness direction of the semiconductor laser element 10. The drive electrode E2 extends from the position of the light emitting end face LES toward the opposite end face, but is interrupted in the middle without completely traversing the semiconductor laser element 10.

  FIG. 4 is a plan view of the inside of the device for explaining the progress of the laser beam inside the semiconductor laser device.

  The laser beam is generated in the active layer 3 </ b> B, but the light that exudes from the active layer 3 </ b> B is affected by the adjacent photonic crystal layer 4. A periodic refractive index distribution structure is formed in the photonic crystal layer 4. As a result of diffraction by this photonic crystal layer, a laser beam indicated by wave number vectors k1 to k4 is generated inside the active layer 3B. The wave vector is a vector whose direction is the normal direction of the wave front (that is, the wave propagation direction) and whose magnitude is the wave number. The laser beams with wave number vectors k1 and k2 are directed toward the light emitting end face LES, and the laser beams with wave number vectors k4 and k3 are directed in the opposite direction.

  The laser beams of the wave number vectors k1 and k2 travel at an angle of ± δθ with respect to the B direction that forms an angle φ with a straight line parallel to the Y axis in the XY plane. The B direction is the direction in which the drive electrode E2 extends. The A direction is a direction perpendicular to the B direction in the XY plane. A coordinate system obtained by rotating the XYZ orthogonal coordinate system by φ around the Z axis is defined as an xyz orthogonal coordinate system. In this case, the A direction coincides with the positive x-axis direction, and the B direction coincides with the negative y-axis direction. The laser beams of the wave number vectors k1 and k2 enter the light emission end face LES and attempt to exit to the outside. The incident angles are θ1 and θ2, respectively. The refraction angle of the laser beam having the wave vector k1 is θ3. θ3 is smaller than 90 degrees. That is, the incident angle θ2 of the laser beam having the wave number vector k2 is equal to or greater than the total reflection critical angle, and total reflection occurs at the light emitting end face LES and is not output to the outside. On the other hand, the incident angle θ1 of the laser beam with the wave vector k1 is less than the total reflection critical angle, and is transmitted to the outside through the light emitting end face LES. Θ4 is an angle formed by the traveling direction of the laser beam totally reflected on the light emitting end face LES and the negative Y-axis direction, and is 90 degrees or more.

  Note that the photonic crystal layer 4 is formed of a plurality of photonic crystal regions 4R.

  FIG. 5 is a plan view of the photonic crystal region 4R having a single periodic structure.

  A photonic crystal is a nanostructure whose refractive index changes periodically, and can strengthen or diffract light of a specific wavelength in a specific direction according to the period. By using this diffraction for light confinement and as a resonator, a laser can be realized. The photonic crystal layer 4 of the present embodiment includes a basic layer 4A and a buried layer (different refractive index portion) 4B periodically embedded in the basic layer 4A.

  In this embodiment, a plurality of holes H are periodically formed in the basic layer 4A made of the first compound semiconductor (GaAs) having the zinc flash structure, and the second compound semiconductor (having the zinc flash structure and having the second compound semiconductor ( The photonic crystal layer 4 is formed by growing a buried layer 4B made of (AlGaAs). Of course, since the photonic crystal is formed, the refractive index of the first compound semiconductor is different from that of the second compound semiconductor. In the present embodiment, the refractive index of the second compound semiconductor is lower than that of the first compound semiconductor. Conversely, the refractive index of the first compound semiconductor may be lower than that of the second compound semiconductor. .

  The different refractive index portions 4B, which are buried layers, are aligned along the A direction and the B direction to form a two-dimensional periodic structure. Here, the pitch between the different refractive index portions 4B in the A direction is a1, and the pitch between the different refractive index portions 4B in the B direction is b1. In addition, a1 = b1 may be sufficient. As a planar shape of each different refractive index portion 4B in the AB plane, a rectangle is shown in the figure, but the planar shape of the different refractive index portion 4B is not limited to this.

  FIG. 6 is a plan view of a photonic crystal region 4R having a single periodic structure different from FIG.

  The different refractive index portions 4B, which are buried layers, are aligned along the A direction and the B direction to form a two-dimensional periodic structure. Here, the pitch between the different refractive index portions 4B in the A direction is a2, and the pitch between the different refractive index portions 4B in the A direction is b2. Note that the relationship of a2> a1 is satisfied. As a planar shape of each different refractive index portion 4B in the AB plane, a rectangle is also shown in the figure, but the planar shape of the different refractive index portion 4B is not limited to this.

  FIG. 7 is a plan view of the photonic crystal region 4R having a plurality of periodic structures.

  That is, the photonic crystal region 4R includes the periodic structure shown in FIG. 5 and the periodic structure shown in FIG. 6 in a single photonic crystal region 4R, and has a period a1 and a period a2. Yes. In addition, the figure shows that both periods in the B direction are set to b2 (= b1).

In the case of such a structure, δθ in FIG. 4 is determined in accordance with the difference between the reciprocal of the period a1 (1 / a1) and the reciprocal of a2 (1 / a2). That is, by determining the periods a1 and a2, it is possible to determine the traveling direction of the laser beam indicated by the wave number vectors k1 and k2. Note that δθ = sin ⁻¹ (δk / k), δk = | π {(1 / a1) − (1 / a2)} |, and k = 2π / λ. λ is the wavelength of the laser light in the semiconductor laser element 10, and k is the wave number of the laser light in the semiconductor laser element 10.

In the case of this embodiment, the inequalities to be satisfied by the parameters θ1 and θ2 and the equivalent refractive index n _dev of the light in the semiconductor laser element 10 are as follows.

0 ≦ θ1 <sin ⁻¹ (1 / n _dev )

θ2 ≧ sin ⁻¹ (1 / n _dev )

In consideration of the fact that the entire photonic crystal is tilted as in the present invention, equations to be satisfied by the respective parameters are as follows.
δθ = φ−sin ⁻¹ (sin θ3 / n _dev )
δk = (2π / λ ₀ ) sin {φ−sin ⁻¹ (sin θ3 / n _dev )}
b1 = b2 = b ₀ / √ (1-sin ² δθ)
a1 = 1 / {(δk / 2π) + (1 / b1)}
a2 = 1 / {(1 / b2)-(δk / 2π)}

B ₀ is a reference period with respect to the B direction (the alignment direction of the lattice points (the arrangement direction of the different refractive index portions)), and is, for example, about 290 nm.

That is, φ is the inclination of the arrangement direction (B direction) of the different refractive index portions with respect to the direction perpendicular to the light emitting end face LES, θ3 is the emission angle of the laser beam, and n _dev is the equivalent refractive index of the light in the semiconductor laser device 10. When the drive current is supplied to the first and second drive electrodes, the resonance wavelengths of the laser beams generated in the first and second regions of the active layer immediately below the first and second drive electrodes are the same. In the first, second, third, and fourth periodic structures (described later), with respect to one of the directions along the basic translation vector, the periods b1 and b2 are √ {1-sin ² (φ−sin ^{− 1} (sin θ3 / n _dev ))}. By changing the setting of the cycle, the emission angle θ3 can be changed.

The total reflection critical angle θc when the total reflection condition of the laser beam of the wave vector k2 is satisfied is given by θc = sin ⁻¹ (1 / n _dev ). In this example, φ = 18.5 °, θ2 > Θc = 17.6 °.

  FIG. 8 is a plan view of a photonic crystal region group 4G having a plurality of photonic crystal layer regions 4R having a plurality of periodic structures. The photonic crystal layer regions 4R are arranged in alignment along the A direction.

  The leftmost photonic crystal layer region 4R is the region Δ1, the second photonic crystal layer region 4R is the region Δ2, the second photonic crystal layer region 4R is the region Δ3, and the fourth photonic crystal layer region 4R is The region Δ4 and the fifth photonic crystal layer region 4R are defined as a region Δ5. For convenience, Δ1 to Δ5 also indicate parameters of the reciprocal of the above period.

  In the region Δ1, the different refractive index portions 4B are arranged in the A direction so as to satisfy the cycle a1 and the cycle a2 shown in FIG. 7, and the different refractive index portions 4B are arranged in the B direction at the cycle b2.

  Similarly, in the region Δ2, the different refractive index portions 4B are arranged in the A direction so as to satisfy the cycle a1 and the cycle a3, and the different refractive index portions 4B are arranged in the B direction at the cycle b2.

  In the region Δ3, the different refractive index portions 4B are arranged in the A direction so as to satisfy the cycle a1 and the cycle a4, and the different refractive index portions 4B are arranged in the B direction at the cycle b2.

  In the region Δ4, the different refractive index portions 4B are arranged in the A direction so as to satisfy the period a1 and the period a5, and the different refractive index portions 4B are arranged in the B direction at the period b2.

  In the region Δ5, the different refractive index portions 4B are arranged in the A direction so as to satisfy the cycle a1 and the cycle a6, and the different refractive index portions 4B are arranged in the B direction at the cycle b2. However, the relationship of a1 <a2 <a3 <a4 <a5 <a6 is satisfied.

  If it demonstrates using a general formula, area | region (DELTA) N (N is a natural number) is arranged from left to right in order with small value of N along A direction, and within area | region (DELTA) N, period a1 in A direction, The different refractive index portions 4B are arranged so as to satisfy the cycle a (N + 1), and the different refractive index portions 4B are arranged in the B direction at the cycle b2, so that aN <a (N + 1) is satisfied.

  As a result, the laser beam can be emitted in different directions according to the difference in the reciprocal of the period.

  FIG. 9 is a plan view of a photonic crystal layer having the photonic crystal region group 4G.

  In the photonic crystal layer 4, the regions Δ1 to Δ5 are sequentially arranged along the A direction. The longitudinal direction of each region Δ1 to Δ5 coincides with the B direction (longitudinal direction of the drive electrode E2). When a drive current is selectively supplied to each drive electrode E2 (a drive voltage is applied between the electrode E1 and a specific electrode E2), laser beams are emitted in different directions from the light emission end face LES (FIG. 3).

  FIG. 10 is a graph showing the incident angle and the outgoing angle of the laser beam with respect to the deflection angle δθ from the reference direction (B direction) (depending on the difference in the reciprocal of the period in each photonic crystal region).

When the difference in the reciprocal of the period increases and the angle δθ increases, the difference between the incident angles θ1 and θ2 increases, and the refraction angle (emission angle) of the laser beam indicated by the k1 vector decreases from 90 ° to 0 °. φ = 18.5 °, and δθ was changed from 0 ° to 18.5 °. The equivalent refractive index n _dev of light in the semiconductor laser element 10 was 3.3. By adjusting the angle δθ, the target laser beam emission angle can be adjusted in a wide range. On the other hand, in the laser beam indicated by the k2 vector, regardless of the value of δθ, since θ2 always exceeds the total reflection critical angle, total reflection always occurs and is not output to the outside.

  FIG. 11 is a plan view of various refractive index portions (structures) 4B having various shapes.

  In the above, a rectangular (A) shape is shown as the shape in the AB plane (XY plane) of the different refractive index portion 4B, but this may be a square (B), an ellipse or a circle (C), It can also be an isosceles or equilateral triangle (D). In addition to the direction of the triangle (D), the base is parallel to the A direction (D), the base is parallel to the B direction (E), and the triangle shown in (D) is rotated 180 degrees (F) You can also Any figure can be rotated and the ratio of dimensions can be changed. Note that the distance between the centers of gravity of each figure can be used as the arrangement period of these figures.

  Note that, when the two periodic structures are overlapped, a difference in the number of holes due to a difference in the period causes a difference in diffraction intensity between the two periodic structures. In order to reduce this, the shape length in the A direction is multiplied by a1 / b1 for the structure of the period a1, and the shape length in the A direction is multiplied by a2 / b2 (= b1) for the structure of the period a2. It is effective to do.

  FIG. 12 is a longitudinal sectional view of the semiconductor laser element.

  The only difference from that shown in FIG. 2 is that a second photonic crystal layer 4 'is provided between the cladding layer 2 and the light guide layer 3A (active layer 3B). The second photonic crystal layer 4 ′ includes a basic layer 4 A ′ made of the same material as the first photonic crystal layer 4 and a different refractive index portion 4 B ′.

  When the photonic crystal layer 4 shown in FIG. 2 is a first photonic crystal layer, the photonic crystal layer 4 has a refractive index distribution structure having a single periodic structure shown in FIG. The second photonic crystal layer 4 ′ has a refractive index distribution in which the single periodic structure with the period a2 shown in FIG. It has a structure. That is, when the overlap of the photonic crystal layers 4 and 4 ′ is seen from the thickness direction of the semiconductor laser element 10, the regions Δ1 to Δ5 are aligned along the A direction as shown in FIG. Will be. Even in the case of such a structure, the same effects as the structure shown in FIG. 2 can be obtained by setting each parameter as described above.

  In the case of manufacturing such a structure, after the formation of the clad layer 2, the same manufacturing method as that for the first photonic crystal layer 4 is performed (however, the growth is stopped when the different refractive index portion 4B is formed). Then, after that, each layer after the light guide layer 3A may be manufactured in the same manner as described above.

  Further, the second photonic crystal layer 4 ′ having the same structure as the first photonic crystal layer 4 including two refractive index periodic structures is used in place of the first photonic crystal layer 4. However, the same effect can be obtained.

  As described above, the semiconductor laser element 10 described above is an edge emitting semiconductor laser element 10, and includes a lower cladding layer 2, an upper cladding layer 5, and a lower cladding layer 2 formed on the substrate 1. Active layer 3B (which may include a light guide layer) interposed between the upper cladding layer 5 and the upper cladding layer 5, and a photonic crystal layer 4 interposed between the active layer 3B and at least one of the upper and lower cladding layers. , 4 ′ and a first drive electrode E2 for supplying a drive current to the first region R of the active layer 3B (a region immediately below one drive electrode E2), and the longitudinal direction of the first drive electrode E2 is When viewed from the thickness direction of the semiconductor laser element 10, the first laser diode is tilted with respect to the normal (Y axis) of the light emitting end face LES of the semiconductor laser element 10, and the first of the photonic crystal layers 4 and 4 ′. The region Δ1 corresponding to the region R is And the first and second periodic structures having different arrangement periods of the different refractive index portions having different refractive indexes from the surroundings, and the arrangement periods (a1, a2) in the first and second periodic structures, respectively. The two laser beams forming a predetermined angle (δθ) with respect to the longitudinal direction (B direction) of the first drive electrode E2 when viewed from the thickness direction of the semiconductor laser element 10 according to the difference of the reciprocal of Only one of these laser beams generated inside the element 10 is set to satisfy the total reflection condition, and the other refraction angle θ3 is set to be less than 90 degrees.

  That is, in the edge-emitting laser element, with respect to light emission by supplying a drive current to the first drive electrode E2, the incident angle θ of one laser beam inside the laser element to the light emission end face LES is set to be equal to or greater than the total reflection critical angle. By doing so, the laser beam can be prevented from being output to the outside. Since the refraction angle θ3 of the other laser beam is less than 90 degrees, the laser beam can be output to the outside through the light emitting end face LES.

  The semiconductor laser device 10 according to the aspect of the present invention further includes a second drive electrode E2 for supplying a drive current to the second region R of the active layer 3B (a region immediately below the second drive electrode E2). When viewed from the thickness direction of the semiconductor laser element 10, the longitudinal direction (B direction) of the second drive electrode E2 is inclined with respect to the normal line (Y axis) of the light emitting end face LES of the semiconductor laser element 10. The region Δ2 corresponding to the second region of the photonic crystal layer has third and fourth periodic structures in which the arrangement periods of the different refractive index portions having different refractive indices from the surroundings have the third and fourth periodic structures, respectively. Depending on the difference between the reciprocal numbers of the arrangement periods (a1, a3) in the third and fourth periodic structures, when viewed from the thickness direction of the semiconductor laser element 10, the length is predetermined with respect to the longitudinal direction of the second drive electrode E2. Two laser beams with an angle δθ of Is generated inside the semiconductor laser device 10, and only one of these laser beams is set to be totally reflected at the light emitting end face LES, and the other refraction angle θ3 is set to be less than 90 degrees. And the difference of the reciprocal number of each arrangement period (a1, a2) in a 2nd periodic structure differs from the difference of the reciprocal number of each arrangement period (a1, a3) in a 3rd and 4th periodic structure.

  In the edge-emitting laser element, regarding the light emission by supplying the drive current to the second drive electrode E2, the incident angle of the one laser beam inside the laser element to the light emitting end face LES is set to be equal to or greater than the total reflection critical angle. The laser beam can be prevented from being output to the outside. Since the refraction angle of the other laser beam is less than 90 degrees, the laser beam can be output to the outside through the light emitting end face LES.

  It should be noted that the same effect is obtained with respect to the third and subsequent drive electrodes E2 from the left.

  Here, in the regions within the photonic crystal layers 4 and 4 ′ corresponding to the respective drive electrodes, the difference in the reciprocal of the arrangement period of the different refractive index portions 4 </ b> B (exit direction determining factor) is different. The difference value determines the laser beam emission direction. Therefore, since the value of the difference (exiting direction determining factor) is different in both regions, the emitting direction of the laser beam is the region Δ1 corresponding to the first drive electrode E2 and the region Δ2 corresponding to the second drive electrode E2. So it will be different. One of the pair of laser beams generated in each region is incident on the light emitting end face LES at a critical angle greater than the total reflection angle, and thus is not emitted to the outside. Therefore, by switching the supply of the drive current to each drive electrode, it becomes possible to output only one direction of laser beam in different directions.

  In this embodiment, a photonic crystal having a different period is based on a square lattice having a period (b1, b1) in the A direction and the B direction, and a rectangular lattice having a period (a1, b1) as the first periodic structure. Although the case of a rectangular lattice with a period of (a2, b1) has been described as the second periodic structure, it is of course possible to use a structure in which the periods in the A direction are different from each other based on a triangular lattice.

  FIG. 13 is a plan view of the inside of the element shown by inverting the top and bottom of the plan view shown in FIG. 4 and slightly changing the refraction angle θ3 of the emitted beam. The same applies to FIG.

  The xyz orthogonal coordinate system is a coordinate system obtained by rotating the XYZ orthogonal coordinate system around the Z axis by an angle + φ, and the + x direction coincides with the + A direction and the + y direction coincides with the −B direction. The arrangement of photonic crystal hole patterns is inclined by an angle φ with respect to the light emitting end face LES. As shown in the figure, the angle formed by the reflection direction of the wave vector k2 (the laser beam traveling direction of the wave vector k2 ′) and the light emitting end face LES is θ2 ′, and the reflection direction of the laser beam of the wave vector k1 (the laser of the wave vector k1 ′). The angle formed between the beam traveling direction) and the light exit end face LES is defined as θ3 ′.

  In the embodiment described above, the laser beam having the wave number vector k2 is set so as to be totally reflected at the light emitting end face LES so that the number of laser beams emitted from the element is one. However, if the power of the laser beam can be reused inside the device, the energy conversion efficiency from electric energy to the laser beam is considered to increase. Therefore, the conditions under which the reflected laser beam Y2 'can be reused are examined. The laser beams (main light waves) corresponding to the wave number vectors k1, k2, k3, k4, k1 ′, and k2 ′ are Y1, Y2, Y3, Y4, Y1 ′, and Y2 ′, respectively. Also assume that the vector is shown. In addition, an angle formed between the X axis and the main light wave Y4 is θt, and an angle formed between the X axis and the main light wave Y3 is θr.

Each parameter θt, θr, θ2 ′, θ3 ′ satisfies the following relational expression. Β ₀ , β ₁ , and β ₂ mean a basic reciprocal lattice vector in the B direction, a basic reciprocal lattice vector in the A direction of the first periodic structure, and a basic reciprocal lattice vector in the A direction of the second periodic structure, respectively. [Beta] ₀ = 2 [pi] / b1 (= b2), [beta] ₁ = _{2 [} pi] / a1, [beta] ₂ = _{2 [} pi] / a2, [Delta] [beta] = [beta] _{2- [} beta] ₁ , and [alpha] = [beta] ₀ / [Delta] [beta].

The angle θr will be described. As shown in FIG. 14, in the xy coordinate system, a vector from the origin O to the point P (βx, βy) is given by an angle θβ = tan ⁻¹ (βy / βx) formed with the x axis. It is done. Here, [theta] t in θβ, βx = (1/2) × Δβ, as [beta] y = beta _0, since it is the case of adding the angle phi, is given by (Equation 1). The remaining parameters are calculated in the same manner and are given by (Equation 2) to (Equation 4).
θt = tan ⁻¹ (2α) + φ (Expression 1)
θr = 180 ° −tan ⁻¹ (2α) + φ (Expression 2)
θ2 ′ = tan ⁻¹ (2α) −φ (Expression 3)
θ3 ′ = 180 ° −tan ⁻¹ (2α) −φ (Expression 4)

  In the absence of any additional structure, in order for the totally reflected main light wave Y2 ′ to contribute to laser light resonance, the angle θ2 ′ of the main light wave Y2 ′ needs to match the angle θt (θ2 ′). = Θt). In this case, φ = 0. Further, the angle θ3 ′ and the angle θr of the reflected main light wave Y1 ′ need to coincide with each other (θ3 ′ = θr). In this case, φ = 0. On the other hand, in order to totally reflect one of the two main light waves Y1 and Y2, it is necessary that φ ≠ 0. Therefore, when total reflection is performed so that the number of beams to be output is one, the main light wave reflected by the light emitting end face LES cannot effectively contribute to laser light resonance.

  Therefore, an additional structure that can use reflected light is examined.

  FIG. 15 is a graph showing the directions of main light waves in the xy coordinate system. The x axis in the xy coordinate system is rotated by an angle φ with respect to the X axis.

In order to make the main light wave Y2 ′ as reflected light coincide with the main light wave Y4 subjected to resonance, the direction of the light wave Y2 ′ may be rotated by an angle 2φ. The coordinates of the tip P4 of the vector indicating the main light wave Y4 in the xy coordinate system are (Δβ / 2, β ₀ ), and the coordinates of the tip P2 ′ of the vector indicating the main light wave Y2 ′ are coordinates obtained by rotating this by −2φ. It is.

On the other hand, in the XY coordinate system, the coordinates (Δβ / 2, β ₀ ) of the vector Y4 (tip P4) in the xy coordinate system are converted into coordinates (XA, YA) rotated by + φ, and the vector Y2 ′ The coordinates are converted into coordinates (XB, YB) obtained by rotating the coordinates of the vector Y4 in the xy coordinate system by −φ.
(XA, YA) = (Δβcosφ / 2-β 0 sinφ, Δβsinφ / 2 + β 0 cosφ
... (Formula 5)
(XB, YB) = (Δβcosφ / 2 + β ₀ sinφ, −Δβsinφ / 2 + β ₀ cos
φ) (Formula 6)

If there is a reciprocal lattice vector equal to the vector ΔY, the main light wave Y2 ′ is coupled to the main light wave Y4. That is, the vector Y4 is obtained by adding the vector ΔY to the vector Y2 ′. The vector ΔY is expressed as follows. If a new periodic structure having a reciprocal lattice vector equal to the vector ΔY is additionally employed, the totally reflected light wave Y2 ′ can be contributed to resonance.
ΔY = (XA−XB, YA−YB) = (− 2β ₀ sinφ, Δβsinφ)

  In this new periodic structure, it is preferable that the different refractive index portions are arranged in a stripe shape. The stripe-shaped periodic structure has a high anisotropy of the optical coupling coefficient and can reduce the influence of the resonance state Y1 and Y2.

  FIG. 16 is a plan view of the inside of the device for explaining main light waves in the active layer 3B.

  The line of intersection between the XY plane and the light emitting end face LES coincides with the X axis. When the above-described vector ΔY exists, the wave vector of the light wave Y2 'having the tip at the coordinate P2' is converted into the wave vector of the light wave Y4 having the tip at the coordinate P4. Let L be a straight line perpendicular to the vector ΔY. The new periodic structure may be set so that the light wave travels in a direction perpendicular to the straight line L in the active layer 3B. In order to control the traveling direction of the light wave in the active layer 3B, the pattern of the diffraction grating layer optically coupled thereto is controlled. In FIG. 12, the upper and lower photonic crystal layers (diffraction grating layers) 4 and 4 'are provided. In the case of such a structure, a photonic crystal layer that achieves the above-described total reflection is produced in the upper diffraction grating layer 4, and the new periodic structure for using reflected light for resonance is formed in the diffraction grating layer 4. (Of course, these periodic structures may be produced by superimposing one or both layers).

  FIG. 17A is a plan view of a diffraction grating layer 4 ′ having a periodic structure that gives the vector ΔY, and FIG. 17B is a cross-sectional view in the XZ plane.

  The diffraction grating layer 4 'includes a basic layer 4A' and a different refractive index portion 4B 'extending in a stripe shape along the straight line L in the XY plane, and these refractive indexes are different. The different refractive index portions 4B 'are periodically embedded in the basic layer 4A'. As a result, a striped periodic refractive index distribution structure is formed in the diffraction grating layer 4 ′, and functions as a diffraction grating layer in which light waves travel in the direction of ΔY. By changing the ratio of the width of the basic layer 4A ′ along the direction perpendicular to the straight line L to the period Λ of the periodic structure, the intensity of diffraction by the stripe-shaped periodic refractive index distribution structure is changed. I can do it. The length L2 of the reciprocal lattice vector of ΔY in the reciprocal lattice space, the period Λ, and the angle θ formed by the straight line L and the X axis are given as follows.

L2 = {(2β ₀ sin φ) ² + (Δβ sin φ) ² } ^1/2 (Expression 7)
Λ = 2π / L2
= 1 / {( ² sin φ / a _y ) ² + ((1 / a _II −1 / a _I ) sin φ) ² } ^1/2 (Expression 8)
θ = θt−φ
= Tan ^-1 (2α)
= Tan ⁻¹ {(2 / a _y ) / (1 / a _II −1 / a _I )} (Equation 9)

Β ₀ = 2π / a _y , β ₁ = 2π / a _I , β ₂ = 2π / a _II , a _y is the period in the B direction, a _I is the period in the A direction of the first periodic structure, a _II shows the period in the A direction of the second periodic structure.

  FIG. 18 is a graph showing the relationship between the laser beam emission angle (refraction angle) θ3, the stripe angle θ, and the period Λ, and FIG. 19 is a chart showing data used in this graph. The vertical axis of the θ (°) data is shown on the left side of the graph, and the vertical axis of the Λ (nm) data is shown on the right side of the graph.

  It can be seen that as the laser beam emission angle θ3 increases, the stripe angle θ increases and the period Λ decreases. In the graph, when the angle θ3 is increased from 0 ° to 70 °, the angle θ increases from 84.27 ° to 89.54 °, and the period Λ decreases from 486.08 nm to 463.43 nm. However, it is within the practically feasible numerical range.

  In FIG. 12, when a periodic pattern for total reflection is formed in both photonic crystal layers 4 and 4 ′, a diffraction grating layer having a new periodic structure that gives the above ΔY separately from these. 4 ″ (the structure is the same as the diffraction grating layer 4 ′ in the case of FIG. 17) can be produced between the upper cladding layer 5 and the diffraction grating layer 4 (FIG. 20A). A diffraction grating layer 4 ″ having a new periodic structure (the structure is the same as that of the diffraction grating layer 4 ′ in FIG. 17) may be formed between the lower cladding layer 2 and the diffraction grating layer 4 ′ (FIG. 20). (B)). As described above, in the above example, the diffraction grating structure (that contributes to resonance by coupling the laser beam reflected by the light emitting end face LES to the laser beam resonating inside the active layer by satisfying the total reflection critical angle condition) The diffraction grating layer of FIGS. 17 and 20 is further provided. In this case, energy use efficiency is increased.

  FIG. 21 is a plan view of the photonic crystal layer 4 having various periodic structures. In any photonic crystal layer 4, the different refractive index portions 4B are periodically embedded in the basic layer 4A. 21A shows a square lattice, FIG. 21B shows a rectangular lattice, FIG. 21C shows a triangular lattice, and FIG. 21D shows a face-centered rectangular lattice. As described above, in the photonic crystal layer 4, two periodic structures having different periods are included so as to overlap in one photonic crystal layer 4, or in the two photonic crystal layers 4, 4 ′. A configuration in which each is included and overlapped in plan view is employed. In these figures, examples of each periodic structure before superposition are shown, and two types of periodic structures are arranged so as to overlap each other so that the directions of the respective basic translation vectors (indicated by arrows) coincide.

  Specifically, in the photonic crystal layer 4 in FIG. 21A, the different refractive index portions 4B are arranged at the lattice point positions of the square lattice. A square lattice has a shape in which squares are arranged without gaps, and the length a of one side of a square constituting one lattice is equal to the length b of the other side. In other words, the horizontal arrangement period a of the different refractive index portions 4B is equal to the vertical arrangement period b. Here, the arrow in the figure represents the basic translation vector of the lattice. Even if the pattern is translated by a linear sum of integral multiples of these basic translation vectors, it overlaps the original pattern. That is, this lattice system has a translational symmetry defined by this basic translation vector.

  In the photonic crystal layer 4 of FIG. 21B, the different refractive index portions 4B are arranged at the lattice point positions of the rectangular lattice. The rectangular lattices having different vertical and horizontal lengths are shapes in which rectangles are arranged without gaps, and the length a of one side of a rectangle constituting one lattice is different from the length b of the other side. In other words, the horizontal arrangement period a of the different refractive index portions 4B is different from the vertical arrangement period b. Here, the arrow in the figure represents the basic translation vector of the lattice. Even if the pattern is translated by a linear sum of integral multiples of these basic translation vectors, it overlaps the original pattern. That is, this lattice system has a translational symmetry defined by this basic translation vector.

  In the photonic crystal layer 4 of FIG. 21C, the different refractive index portions 4B are arranged at the lattice point positions of the triangular lattice. The triangular lattice is a shape in which triangles are arranged without gaps, and the length of the bases of the triangles constituting one lattice is a, and the height is b. When the triangle is an equilateral triangle, in other words, the length a of the base is the horizontal arrangement period a of the different refractive index portions 4B, and the vertical arrangement period b is √2 times a. Here, the arrow in the figure represents the basic translation vector of the lattice. Even if the pattern is translated by a linear sum of integral multiples of these basic translation vectors, it overlaps the original pattern. That is, this lattice system has a translational symmetry defined by this basic translation vector.

  In the photonic crystal layer 4 of FIG. 21D, the different refractive index portions 4B are arranged at the lattice point positions of the face-centered rectangular lattice. The face-centered rectangular lattice is a lattice additionally provided with a lattice point at the center position in each lattice of the rectangular lattice, and the rectangular lattice itself is formed by arranging rectangles without gaps. Here, the arrow in the figure represents the basic translation vector of the lattice. Even if the pattern is translated by a linear sum of integral multiples of these basic translation vectors, it overlaps the original pattern. That is, this lattice system has a translational symmetry defined by this basic translation vector.

  As described above, the A axis is inclined with respect to the X axis, and these are not parallel. In other words, in any of the photonic crystal layers 4 described in FIGS. 2 to 21, when viewed from the thickness direction of the semiconductor laser element 10, the different refractive index portion 4 </ b> B in the photonic crystal layer 4 has its lattice. The direction of the basic translation vector (A axis, B axis) of the lattice structure is different from the direction (X axis) parallel to the light emitting end face LES (see FIG. 4). . In this case, one laser beam can satisfy the total reflection critical angle condition by setting the inclination to a certain value or more.

  The lattice structure of the photonic crystal layer, when viewed from the thickness direction, is a square lattice and a rectangular lattice, a rectangular lattice and a rectangular lattice, a triangular lattice and a face-centered rectangular lattice, a face-centered rectangular lattice and a surface. It can be constituted by a combination of a square lattice, a rectangular lattice, a triangular lattice, or a face-centered rectangular lattice, such as a centered rectangular lattice. That is, it is possible to configure a single grating as described above by combining gratings having different pitches in one direction.

  When the above-described square lattice (FIG. 21A) and the square lattice (FIG. 21B) are overlapped, the photonic crystal layer 4 (or 4, 4 ′) has a tetragonal lattice and a rectangular lattice of crystals. A period of one axial direction of the hole lattice is a1, a period of the axial direction perpendicular to the one axis is b1, a period of one axial direction of the rectangular lattice is a2, When the period in the axial direction orthogonal to one of the axes is b2, a1 = b1, a1 ≠ a2, and b1 = b2 can be satisfied. In this case, a standing wave state is formed in the photonic crystal layer surface by oblique light waves that are not orthogonal to each other, and the angle formed by the oblique light waves changes according to the difference between a1 and a2.

  When two rectangular lattices (FIG. 21B) are overlapped, the photonic crystal layer 4 (or 4, 4 ′) includes the crystal structures of the first and second rectangular lattices. , The period of one axial direction of the first rectangular lattice is a1, the period of the axial direction orthogonal to the one axis is b1, the period of one axial direction of the second rectangular lattice is a2, When the period in the axial direction orthogonal to the axis is b2, a1 ≠ a2 and b1 = b2 can be satisfied. In this case, a standing wave state is formed in the photonic crystal layer surface by oblique light waves that are not orthogonal to each other, and the angle formed by the oblique light waves changes according to the difference between a1 and a2.

  When two face-centered rectangular lattices (FIG. 21D) are superimposed, the photonic crystal layer 4 (or 4, 4 ′) has a crystal structure of the first and second face-centered rectangular lattices. The period of one axial direction of the first face-centered rectangular lattice is a1, the period of the axial direction orthogonal to the one axis is b1, and one axis of the second face-centered rectangular lattice is If the period in the direction is a2 and the period in the axial direction orthogonal to the one axis is b2, a1 ≠ a2 and b1 = b2 can be satisfied. In this case, a standing wave state is formed in the photonic crystal layer surface by oblique light waves that are not orthogonal to each other, and the angle formed by the oblique light waves changes according to the difference between a1 and a2.

  One face-centered rectangular lattice can be a triangular lattice. The triangular lattice is a special case in which the angle formed by the basic translation vectors forming the lattice of the face-centered rectangular lattice is 60 degrees.

  As shown in FIG. 2, the semiconductor laser element 10 includes regions (first region, second region...) R immediately below the drive electrode of the active layer 3B. The different refractive index portion 4B of the photonic crystal layer corresponding to the first region R of the active layer 3B and the different refractive index portion 4B of the photonic crystal layer corresponding to the second region R of the active layer 3B are the first region. The laser beams output from the R region and the second region R can be set to have different shapes when viewed from the thickness direction of the semiconductor laser device 10 so that the refraction angles of the laser beams are different and the intensities are matched. In other words, the size of the hole (different refractive index portion) is changed so that the diffraction intensities of a plurality of photonic crystals are the same. Since the intensity is the same, it can be easily applied to electronic devices such as laser printers and radars.

  For example, the hole (different refractive index portion) changes the length along the direction along the basic translation vector having a different period. Specifically, in the first region R, the dimension of the different refractive index portion 4B along the direction in which the arrangement periods of the different refractive index portions 4B in the first periodic structure and the second periodic structure are different (for example, the B axis) is In the second region R, the different refractive index portions along the direction in which the arrangement periods of the different refractive index portions 4B in the third and fourth periodic structures are different (for example, the B axis) are different depending on the positions along the different directions. The dimension of 4B changes according to the position along the said different direction. As a result, the diffraction intensities in the first periodic structure and the second periodic structure, or the diffraction intensities in the third periodic structure and the fourth periodic structure can be made uniform, and the oscillation can be stabilized.

  In addition, the period along the basic translation vector in the first periodic structure in the first region R can be continuously changed as the third periodic structure in the second region R is approached. In this case, there is an effect that reflection can be prevented from occurring at the interface between the photonic crystals having different periods.

  Next, signal processing of the control circuit unit will be described with reference to FIG. The control circuit unit 101 controls the emission of the laser beam by the semiconductor laser element 10 and the movement (rotation) of the photosensitive drum 102 by performing signal processing on the print information input by an external signal. The control circuit unit 101 includes a signal processing unit 111, a laser element current supply circuit unit 112, and a photosensitive drum drive circuit unit 113.

  When the external signal is a signal related to print information, the signal processing unit 111 inputs the signal related to the print information to the laser element current supply circuit unit 112 and the photosensitive drum drive circuit unit 113. The external signal related to the print information is, for example, a print instruction signal input from a user who uses a terminal connected to the laser printer 100.

  Based on the external signal, the signal processing unit 111 sends a signal related to print information for each batch irradiation unit in the semiconductor laser element 10 to the laser element current supply circuit unit 112 (that is, print for each line unit in the photosensitive drum 102). Input signal). The signal processing unit 111 receives a signal indicating that the photosensitive drum 102 is to be moved to the photosensitive drum driving circuit unit 113 in response to the completion of the irradiation of the laser beam for one line on the photosensitive drum by the semiconductor laser element 10. To do.

  The laser element current supply circuit unit 112 receives a signal related to print information for each batch irradiation unit in the semiconductor laser element 10 from the signal processing unit 111 (that is, a signal related to print information for each line unit in the photosensitive drum 102). The drive current is supplied to the drive electrode E2 corresponding to the irradiation position in each row of the photosensitive drum 102.

  FIG. 23 is a diagram for explaining the irradiation state of the laser beam on the photosensitive drum. FIG. 24 is a plan view of the semiconductor laser device. The squares drawn on the photosensitive drum 102 in FIG. 23 and the row numbers 301 and the column numbers 302 of the squares are described for explanation, and are not actually drawn on the photosensitive drum 102. A circle in each square indicates a portion irradiated with the laser beam by the semiconductor laser element 10. As shown in FIG. 23, there are 17 (17 columns) different positions for each row. Drive electrodes E201 to E217 in FIG. 24 are drive electrodes E2 corresponding to the irradiation positions in the 1st to 17th rows of the photosensitive drum 102, respectively.

  As an example, a laser beam irradiation image in the first row in FIG. 23 will be described. When processing the signal in the first row in FIG. 23, the signal processing unit 111 supplies the laser element current supply circuit unit 112 with 1-3, 5-7, 9, 11, 12, 14 in the photosensitive drum 102. , 16 and 17 are input with a signal indicating that the semiconductor laser element is irradiated. The laser element current supply circuit unit 112 is a driving electrode of the semiconductor laser element 10 corresponding to the first to third, fifth, seventh, ninth, eleventh, twelfth, fourteenth, sixteenth and seventeenth columns based on the signal. A drive current is supplied to the electrodes E201 to E203, E205 to E207, E209, E211, E212, E214, E216, and E217. By supplying the driving current, the laser beam is irradiated from the semiconductor laser element 10 to the irradiation positions in the first, third, fifth, seventh, ninth, eleventh, twelfth, fourteenth, sixteenth and seventeenth rows of the photosensitive drum 102.

  Returning to FIG. 22, the photosensitive drum drive circuit unit 113 receives a signal from the signal processing unit 111 to move the photosensitive drum 102, and rotates the photosensitive drum 102 by one line with respect to the irradiation position of the laser beam (see FIG. 22). Relatively moved in a direction perpendicular to the first direction). More specifically, the photosensitive drum drive circuit unit 113 inputs a signal for rotating the photosensitive drum 102 by one line to a drive mechanism (not shown) of the photosensitive drum 102, and the drive mechanism The drum 102 is rotated by one line. The timing at which the photosensitive drum drive circuit unit 113 inputs a signal for rotating the photosensitive drum 102 by one line is the timing at which the semiconductor laser element 10 irradiates the photosensitive drum 102 with a laser beam.

  The processing by the signal processing unit 111, the laser element current supply circuit unit 112, the semiconductor laser device 10, and the photosensitive drum driving circuit unit 113 described above is repeatedly performed while an external signal is input to the signal processing unit 111.

  Returning to FIG. 1, the photosensitive drum 102 is a cylindrical photosensitive member that adsorbs toner by charges generated by irradiation with a laser beam and transfers the toner to a print medium. The photosensitive drum 102 rotates in a direction (rotation direction) indicated by an arrow in the drawing with a direction parallel to the first direction D1 as a rotation axis l1. As described above, the photosensitive drum 102 is rotated line by line by the photosensitive drum drive circuit unit 113.

  The beam shaping lens unit 103 has a function as a beam shaping optical system for shaping a laser beam, and includes a collimating lens, a condensing lens, a scanning lens, and the like. The collimating lens is a lens that collimates the laser beam. The condensing lens is a lens used for condensing, such as a cylinder lens. The scanning lens is a lens that increases the focusing accuracy of the laser beam focused on the photosensitive drum and reduces the beam spot on the photosensitive drum. Each lens may be a refractive index distribution lens using a refracting surface or a diffractive lens using a reflecting surface.

  The power source 104 is connected to the control circuit unit 101. When the power source 104 is turned on, the control circuit unit 101 processes external signals.

  As described above, in the laser printer 100, a plurality of laser beams emitted from the semiconductor laser element 10 and having different emission directions are at different positions along the direction (row direction) parallel to the first direction D1 on the photosensitive drum 102. Each is irradiated at once.

  Semiconductor laser elements used in conventional laser printers emit laser beams only in one direction, so there is a limit to increasing the number of laser beams (number of emitters) by designing the element structure and beam control optical system. . In order to increase the printing speed, it is necessary to increase the pulse speed. However, high-speed pulse operation causes electrical and thermal crosstalk between the emitters of the element, and the on / off signal may become unclear, so there is a limit to increasing the pulse speed, and as a result, The printing speed has not been sufficiently increased. In this regard, in the laser printer 100 in which a plurality of laser beams are irradiated at once, the printing speed can be improved without increasing the pulse speed.

  As shown in FIG. 25, in the conventional laser printer 200, the laser beam emitted from the semiconductor laser element 20 is converted into parallel light by the collimating lens 201 and further condensed by the cylinder lens 202, and then rotated at a constant speed. It was accurately reflected by the polygon mirror 203 to be performed and condensed on the photosensitive drum 205 by the scanning lens 204. Due to the presence of the polygon mirror 203, the printing speed is limited even by the rotational speed of the polygon mirror 203. In this respect, since the laser printer 100 does not require a mechanical drive system such as a polygon mirror, the limitation on the printing speed described above does not pose a problem.

  The laser beam emission direction is such that the laser beam generated in the adjacent region in the first direction D1 is more inclined in the first direction D1, so that the correspondence between each laser beam and the irradiation position on the photosensitive drum 102 is clear. Thus, printing can be performed reliably and more appropriately.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention is modified without departing from the scope described in the claims or applied to others. It may be.

  For example, the semiconductor laser element of the laser printer 100 may use a semiconductor laser element 10 </ b> A including a first photonic crystal layer 41 and a second photonic crystal layer 43 as the photonic crystal layer 4.

  The laser printer 100 may include a semiconductor laser element 10A described later instead of the semiconductor laser element 10. Hereinafter, the details of the semiconductor laser element 10A will be described with reference to FIGS.

  First, the configuration of the semiconductor laser element 10A according to this embodiment will be described. FIG. 26 is a schematic perspective view of the semiconductor laser device. FIG. 27 is a diagram showing a cross-sectional configuration along the line XXVII-XXVII of the semiconductor laser element. FIG. 28 is a diagram showing a cross-sectional configuration along the line XXVIII-XXVIII of the semiconductor laser element. FIG. 29 is a plan view of the semiconductor laser device.

  The semiconductor laser element 10A is an edge emitting semiconductor laser element. The semiconductor laser element 10A includes a lower clad layer 2, a lower light guide layer 3A, an active layer 3B, an upper light guide layer 3C, a photonic crystal layer 4, an upper clad layer 5, and contacts, which are sequentially formed on the semiconductor substrate 1. Layer 6 is provided. On the back side of the semiconductor substrate 1, an electrode E <b> 1 is provided on the entire surface, and on the contact layer 6, a plurality of drive electrodes E <b> 2 are provided.

A part of the surface on the contact layer 6 is covered with an insulating film SH. The insulating film SH can be formed from, for example, SiN or SiO ₂ . A plurality of electrode pads EP are disposed on the insulating film SH.

  The planar shape of the semiconductor laser element 10A is a rectangle. When an XYZ three-dimensional orthogonal coordinate system is set, the thickness direction is the Z axis, the width direction is the X axis, and the direction perpendicular to the light emitting end face LES is the Y axis. To do. In the XY plane, the extending longitudinal direction of each drive electrode E2 is parallel to a straight line parallel to the Y axis.

  The upper surface of the contact layer 6 (the surface on which the insulating film SH is formed) is viewed from the light emitting end surface LES side in the Y-axis direction when viewed from the thickness direction of the semiconductor laser element 10A, and the first region 6a, the second region 6b, And the third region 6c. The second region 6b is located between the first region 6a and the third region 6c in the Y-axis direction. Each region 6a6b, 6c extends in the X-axis direction. The insulating film SH is disposed on the third region 6 c of the contact layer 6.

  The plurality of drive electrodes E2 are juxtaposed in the X-axis direction in the second region 6b when viewed from the thickness direction of the semiconductor laser element 10A. Each drive electrode E2 has a rectangular shape. Specifically, each drive electrode E2 has a rectangular shape with the long side in the Y-axis direction. That is, the plurality of drive electrodes E2 are juxtaposed in the short side direction of the drive electrode E2. The longitudinal direction of the drive electrode E2 is parallel to the normal line (Y axis) of the light emitting end face LES of the semiconductor laser element 10A when viewed from the thickness direction of the semiconductor laser element 10A.

  When a current is passed between the upper and lower electrodes E1, E2, a current flows through a region R immediately below one of the electrodes E2, and the region R emits light. The plurality of drive electrodes E2 supply a drive current to a plurality of regions R located in parallel with the light emitting end face LES and extending in the active layer 3B, that is, in the X-axis direction, in the active layer 3B.

  As shown in FIGS. 28 and 29, each electrode pad EP is electrically connected to the corresponding drive electrode E2 through a wiring W1 disposed on the insulating film SH. The number of drive electrodes E2 and the number of electrode pads EP are the same. In the present embodiment, the plurality of electrode pads EP are arranged in a plurality of rows along the X-axis direction. The plurality of electrode pads EP are located above the third region 6c.

  In the semiconductor laser element 10 </ b> A, the photonic crystal layer 4 includes a first photonic crystal layer 41 and a second photonic crystal layer 43. That is, the first photonic crystal layer 41 and the second photonic crystal layer 43 include a basic layer 4A and a plurality of embedded layers (different refractive index portions) 4B periodically embedded in the basic layer 4A. Each has. The first photonic crystal layer 41 and the second photonic crystal layer 43 are located in the same layer, and the second photonic crystal layer 43 is closer to the light emitting end face LES than the first photonic crystal layer 41. positioned.

  A photonic crystal is a nanostructure whose refractive index changes periodically and can strengthen or diffract light of a specific wavelength in a specific direction according to the period. For example, a laser can be realized by using this diffraction for light confinement and using it as a resonator.

  In this embodiment, a plurality of holes H are periodically formed in the basic layer 4A made of the first compound semiconductor (GaAs) having the zinc flash structure, and the second compound semiconductor (having the zinc flash structure and having the second compound semiconductor ( The photonic crystal layer 4 is formed by growing a buried layer 4B made of (AlGaAs). Since the photonic crystal is formed, the first compound semiconductor and the second compound semiconductor have different refractive indexes. In the present embodiment, the refractive index of the second compound semiconductor is lower than that of the first compound semiconductor. Conversely, the refractive index of the first compound semiconductor may be lower than that of the second compound semiconductor.

  The shape of the burying layer 4B in the XY plane may be a rectangle, a square, an ellipse, or a circle, or an isosceles triangle or an equilateral triangle, as shown in FIGS. As a triangle, a triangle whose base is parallel to the X direction (shown in (D)), a triangle whose base is parallel to the Y direction (shown in (E)), or the triangle shown in (D) is rotated 180 degrees. A triangle (shown in (F)) can also be adopted. Any figure can be rotated and the ratio of dimensions can be changed. As the arrangement period of these figures, the distance between the centers of gravity of the figures can be used. In this embodiment, the circular shape (true circle) shown in (C) is adopted as the shape of the buried layer (different refractive index portion) 4B.

  FIG. 30 is a plan view of the first photonic crystal layer.

The first photonic crystal layer 41 is located below the plurality of drive electrodes E2. In the first photonic crystal layer 41, when viewed from the thickness direction, the buried layer 4B is disposed at each lattice point (Γ point) constituting a square lattice. That is, the buried layer 4B is aligned in the X-axis direction and the Y-axis direction to form a two-dimensional periodic structure. As a result, the first photonic crystal layer 41 has a periodic structure in which the arrangement period of the buried layers 4B is the same over a region corresponding to the plurality of regions R. The period P1 in the alignment direction of the buried layer 4B is:
λ ₀ / n ₁
Is set to λ ₀ is the wavelength of the laser light in vacuum. n ₁ is an equivalent refractive index of light in the first photonic crystal layer 41.

  The laser beam is generated in the active layer 3B, but the light oozing out from the active layer 3B is affected by the adjacent first photonic crystal layer 41. A periodic refractive index distribution structure as shown in FIG. 30 is formed in the first photonic crystal layer 41. As a result of diffraction by the first photonic crystal layer 41, a laser beam is generated in the direction indicated by the arrow in FIG. Since the first photonic crystal layer 41 has a periodic structure in which the arrangement period of the buried layer 4B is the same over a region corresponding to the plurality of regions R, the laser is emitted from each region R in the same direction. A beam is output. In the present embodiment, a laser beam directed in the Y-axis direction, that is, toward the light emitting end surface LES is used.

  The arrangement of the buried layer 4B in the first photonic crystal layer 41 is not limited to the arrangement shown in FIG. 30, and may be the arrangement shown in FIGS.

In FIG. 31A, the buried layer 4B is disposed at each M point of the square lattice. The buried layer 4B is inclined in the X axis direction and the Y axis direction by 45 degrees and is aligned in two directions orthogonal to each other. The period P2 in the alignment direction of the buried layer 4B is:
²⁻¹ / ² × λ ₀ / n ₁
Is set to Also in this case, the traveling direction of the main light wave is a direction along the X-axis direction and the Y-axis direction, as indicated by arrows in the drawing.

In FIG. 31B, the buried layer 4B is disposed at the Γ point of the triangular lattice. The period P3 of the buried layer 4B is
λ ₀ / n ₁
Is set to In this case, the traveling direction of the main light wave is the direction of 60 ° intervals indicated by arrows in the figure. In FIG. 31C, the buried layer 4B is disposed at each point J of the triangular lattice. The period P4 of the buried layer 4B is
2 × 3 ^−1/2 × λ ₀ / n ₁
Is set to In this case, the traveling direction of the main light wave is the direction of 60 ° intervals indicated by arrows in the figure.

  In the semiconductor laser device 10A, the lower clad layer 2, the lower light guide layer 3A, the active layer 3B, the upper light guide layer 3C, the first photonic crystal layer 41, the upper clad layer 5, and the plurality of drive electrodes E2 are included in the oscillation unit. Configure. The oscillation unit generates a plurality of laser beams and outputs the generated plurality of laser beams in the same direction.

  FIG. 32 is a plan view of the second photonic crystal layer.

Also in the second photonic crystal layer 43, the buried layer 4B constitutes a two-dimensional periodic structure. The plurality of buried layers 4B in the second photonic crystal layer 43 are arranged at lattice point positions of a predetermined lattice structure. In this predetermined lattice structure, an angle φ formed by two basic translation vectors is θ, where θ is an angle formed by a direction orthogonal to one basic translation vector of the predetermined lattice structure and a laser beam emission direction.
φ = tan ⁻¹ {sin θ / ( ² cos ² (θ / 2))}
Meet.

The period P5 of the lattice point in the direction along one basic translation vector of the lattice structure of the buried layer 4B in the second photonic crystal layer 43 is:
λ ₀ / (n ₂ × sin θ)
Meet. The period P6 of the lattice points in the direction orthogonal to one basic translation vector of the lattice structure of the buried layer 4B in the second photonic crystal layer 43 is as follows when m is an arbitrary natural number:
(2m-1) × λ ₀ / (2n ₂ )
Meet. n ₂ is an equivalent refractive index of light in the second photonic crystal layer 43.

  The angle φ formed by the two basic translation vectors (or the interval between the buried layers 4B in the X-axis direction) changes continuously as shown in FIG. 32 according to the position in the X-axis direction. That is, the second photonic crystal layer 43 has the above-described periodic structure in which the arrangement period of the buried layer 4B is different for each region corresponding to the plurality of regions R. The second photonic crystal layer 43 constitutes a deflection unit that deflects a plurality of laser beams output in the same direction from the oscillation unit in different directions and emits them from the light emitting end face by the periodic structure.

The second photonic crystal layer 43 causes, in each region corresponding to the plurality of regions R, interference that weakens light transmitted in the same direction as the output direction of the laser beam from the oscillating unit, and the light emitting end surface LES. Intensive interference is generated for the light diffracted in the laser beam emission direction from the laser beam. In the second photonic crystal layer 43, when viewed in the thickness direction, the buried layer 4B has an equal interval (same as in the Y-axis direction, that is, the same direction as the laser beam output direction from the oscillation unit). Arranged in an array period). The period of the buried layer 4B in the Y-axis direction is such that m is an arbitrary natural number,
(2m-1) × λ ₀ / (2n ₂ )
Is set to The period of the buried layer 4B in the X-axis direction parallel to the light emission end face LES is:
λ ₀ / (n ₂ × sin θ)
Is set to

  As described above, in the semiconductor laser element 10A, the first photonic crystal layer 41 has a periodic structure in which the arrangement period of the buried layers 4B is the same over the regions corresponding to the plurality of regions R. From the oscillation unit, a laser beam is output in the same direction for each of the plurality of drive electrodes E2. Since the second photonic crystal layer 43 has a periodic structure in which the arrangement period of the buried layer 4B is different for each region corresponding to the plurality of regions R, the deflection unit outputs the same in the same direction. The laser beams thus produced are deflected in different directions and emitted from the light emitting end face LES.

  In the semiconductor laser device 10A, the oscillation unit and the deflection unit are separated, and the first photonic crystal layer 41 has a periodic structure in which the arrangement period of the buried layer 4B is the same over a region corresponding to the plurality of regions R. have. For this reason, the oscillation threshold is constant for each laser beam, and stable operation can be realized.

  The second photonic crystal layer 43 causes interference that weakens light transmitted in the same direction as the output direction of the laser beam from the oscillation unit in each region corresponding to the plurality of regions R, and from the light emitting end surface LES. Interference that reinforces the light diffracted in the laser beam emission direction. Thereby, the deflecting unit can surely deflect each laser beam output in the same direction from the oscillation unit in a different direction and emit the laser beam from the light emitting end surface.

  The laser printer 100 according to the present embodiment may include a plurality of semiconductor laser elements 10 as shown in FIG. FIG. 33 is a diagram for explaining a laser printer according to a modification of the present embodiment. The laser printer 100 includes the semiconductor laser element 10, the control circuit unit 101, the photosensitive drum 102, the beam shaping lens unit 103, and the power source 104, similarly to the laser printer 100 according to the above-described embodiment. . A plurality of semiconductor laser elements 10 (three semiconductor laser elements 10 in this modification) are juxtaposed along a direction parallel to the first direction D1. The irradiation area on the photosensitive drum 102 of the laser beam emitted from each semiconductor laser element 10 is different for each semiconductor laser element 10. The laser beams emitted from the light emitting end faces LES of the respective semiconductor laser elements 10 are respectively irradiated at different positions along the direction parallel to the first direction D1 on the photosensitive drum 102.

  In the laser printer 100 of this modification, the laser beam irradiation range to the photosensitive drum 102 can be increased as compared with the laser printer 100 configured to include only one semiconductor laser element 10. Therefore, it is possible to perform laser beam batch irradiation to all irradiation positions for one row even on the photosensitive drum 102 that is long in the axial direction. In this modification, a semiconductor laser element 10 </ b> A may be provided instead of the semiconductor laser element 10.

DESCRIPTION OF SYMBOLS 10,10A ... Semiconductor laser element, 1 ... Semiconductor substrate, 2 ... Lower clad layer, 3A ... Lower light guide layer, 3B ... Active layer, 3C ... Upper light guide layer, 4 ... Photonic crystal layer, 4B ... Embedded layer, DESCRIPTION OF SYMBOLS 5 ... Upper clad layer, 6 ... Contact layer, 41 ... 1st photonic crystal layer, 43 ... 2nd photonic crystal layer, 100 ... Laser printer, 101 ... Control circuit part, 102 ... Photosensitive drum, 103 ... Beam shaping lens , 104 ... Power supply, 111 ... Signal processing unit, 112 ... Laser element current supply circuit unit, 113 ... Photosensitive drum drive circuit unit, D1 ... First direction, E2 ... Drive electrode, l1 ... Rotation axis, LES ... Light emission end face .

Claims (8)

A laser printer comprising: an exposure unit that irradiates a photoconductor with a laser beam to form a latent image on the photoconductor; and a moving unit that moves the photoconductor relative to an irradiation position of the laser beam. And
The exposure means includes a lower cladding layer, an upper cladding layer, an active layer interposed between the lower cladding layer and the upper cladding layer, and at least one of the active layer and the upper and lower cladding layers. And a plurality of drive electrodes for supplying a drive current to a plurality of regions of the active layer, and generating a laser beam from the plurality of regions by supplying the drive current Including an edge-emitting semiconductor laser element,
The plurality of regions are parallel to the light emitting end surface of the semiconductor laser element and are arranged in a first direction in which the active layer extends, and an emission direction of the laser beam generated in the plurality of regions from the light emitting end surface Are different,
The semiconductor laser element and the photoconductor are arranged such that the laser beam emitted from the light emitting end face is irradiated to different positions along a direction parallel to the first direction on the photoconductor. And
The moving means moves the photosensitive member in a direction perpendicular to the first direction with respect to an irradiation position of the laser beam emitted from the light emitting end surface ,
The semiconductor laser element generates a plurality of laser beams, and outputs a plurality of generated laser beams in the same direction, and a plurality of laser beams output in the same direction from the oscillation unit in different directions. And a deflecting unit that deflects the light to exit from the light exit end face,
The oscillation unit includes the lower cladding layer, the upper cladding layer, the active layer, a first photonic crystal layer as the photonic crystal layer, and the plurality of drive electrodes,
The deflection unit includes a second photonic crystal layer,
The first photonic crystal layer has a periodic structure in which the arrangement period of different refractive index portions having different refractive indexes from the surroundings is the same over the region corresponding to the plurality of regions,
The second photonic crystal layer has a periodic structure in which the arrangement period of the different refractive index portions having different refractive indexes from the surroundings is different for each region corresponding to the plurality of regions.
A laser printer characterized by the above.   A laser printer comprising: an exposure unit that irradiates a photoconductor with a laser beam to form a latent image on the photoconductor; and a moving unit that moves the photoconductor relative to an irradiation position of the laser beam. And
  The exposure means includes a lower cladding layer, an upper cladding layer, an active layer interposed between the lower cladding layer and the upper cladding layer, and at least one of the active layer and the upper and lower cladding layers. And a plurality of drive electrodes for supplying a drive current to a plurality of regions of the active layer, and generating a laser beam from the plurality of regions by supplying the drive current Including an edge-emitting semiconductor laser element,
  The plurality of regions are parallel to the light emitting end surface of the semiconductor laser element and are arranged in a first direction in which the active layer extends, and an emission direction of the laser beam generated in the plurality of regions from the light emitting end surface Are different,
  The semiconductor laser element and the photoconductor are arranged such that the laser beam emitted from the light emitting end face is irradiated to different positions along a direction parallel to the first direction on the photoconductor. And
  The moving means moves the photosensitive member in a direction perpendicular to the first direction with respect to an irradiation position of the laser beam emitted from the light emitting end surface,
  The active layer includes a first region and a second region as the plurality of regions,
  The plurality of drive electrodes include a first drive electrode for supplying a drive current to the first region, and a second drive electrode for supplying a drive current to the second region,
  The longitudinal direction of the first drive electrode is inclined with respect to the normal of the light emitting end face when viewed from the thickness direction of the semiconductor laser element,
  The region corresponding to the first region of the photonic crystal layer has first and second periodic structures in which arrangement periods of different refractive index portions having different refractive indexes from the surroundings are different from each other,
  A predetermined angle with respect to the longitudinal direction of the first drive electrode when viewed from the thickness direction of the semiconductor laser element according to the difference between the reciprocals of the arrangement periods of the first and second periodic structures. Wherein two or more laser beams are generated inside the semiconductor laser element,
  Among these laser beams, one toward the light emitting end surface is set to have a refraction angle of less than 90 degrees with respect to the light emitting end surface, and at least one other toward the light emitting end surface is formed on the light emitting end surface. Is set to satisfy the total reflection critical angle condition,
  The longitudinal direction of the second drive electrode is inclined with respect to the normal of the light emitting end face when viewed from the thickness direction of the semiconductor laser element,
  The region corresponding to the second region of the photonic crystal layer has third and fourth periodic structures in which arrangement periods of different refractive index portions having different refractive indexes from the surroundings are different from each other,
  A predetermined angle with respect to the longitudinal direction of the second drive electrode when viewed from the thickness direction of the semiconductor laser element according to the difference between the reciprocals of the arrangement periods in the third and fourth periodic structures. Wherein two or more laser beams are generated inside the semiconductor laser element,
  Among these laser beams, one toward the light emitting end surface is set to be refracted less than 90 degrees with respect to the light emitting end surface, and at least one other toward the light emitting end surface is formed on the light emitting end surface. For the total reflection critical angle condition,
  The difference between the reciprocal numbers of the array periods in the first and second periodic structures is different from the difference between the reciprocal numbers of the array periods in the third and fourth periodic structures.
A laser printer characterized by the above. The emission direction of the laser beam generated in the region adjacent to the arbitrary one region in the first direction is greater than the emission direction of the laser beam generated in any one region of the plurality of regions. , More inclined in the first direction,
The laser printer according to claim 1 or 2 , characterized in that The moving means moves the photoconductor in a direction orthogonal to the first direction every time the laser beam is irradiated onto the photoconductor by the exposure means.
The laser printer according to any one of claims 1 to 3 . The photoreceptor is a photosensitive drum;
The moving means rotates the photosensitive drum in a rotation direction having a rotation axis in a direction parallel to the first direction;
The laser printer as described in any one of Claims 1-4 . The semiconductor laser element has two periodic structures in which regions corresponding to the plurality of regions of the active layer of the photonic crystal layer have different arrangement periods of different refractive index portions having different refractive indexes from the surroundings. The difference between the reciprocal numbers of the arrangement periods in the two periodic structures is different for each region corresponding to the plurality of regions of the active layer of the photonic crystal layer.
The laser printer according to any one of claims 1 to 5 , wherein The semiconductor laser element has two periodic structures in which regions corresponding to the plurality of regions of the active layer of the photonic crystal layer have different arrangement periods of different refractive index portions having different refractive indexes from the surroundings. And forming a predetermined angle with respect to the longitudinal direction of the plurality of drive electrodes when viewed from the thickness direction of the semiconductor laser element according to the difference between the reciprocals of the arrangement periods of the two periodic structures. Two or more laser beams are generated inside the semiconductor laser element, and one of the laser beams directed to the light emitting end face is set to have a refraction angle of less than 90 degrees with respect to the light emitting end face. Another at least one toward the light emitting end face is set to satisfy the total reflection critical angle condition with respect to the light emitting end face,
The laser printer according to any one of claims 1 to 6 , wherein: The second photonic crystal layer causes, in each region corresponding to the plurality of regions, interference that weakens light transmitted in the same direction as the output direction of the laser beam from the oscillation unit, and the light emission Intensifying interference that diffracts the light diffracted in the laser beam exit direction from the end face,
The laser printer according to claim 1 .

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