JP2011018798A - Laser module, bar code scanner and photoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a laser module which can be made compact; a bar code scanner; and a photoelectric sensor.SOLUTION: The laser module 20 includes a photonic crystal laser element 1 comprising a substrate, a first conductivity type clad layer, a light-emitting layer, a second conductivity type clad layer, and a photonic crystal layer. The first conductivity type clad layer is formed on the substrate. The light-emitting layer is formed on the first conductivity type clad layer, and emits light. The second conductivity type clad layer is formed on the light-emitting layer. The photonic crystal layer is formed between the first conductivity type clad layer and second conductivity type clad layer, in the first conductivity type clad layer, or in the second conductivity type clad layer, and has a low-refractive-index part and a high-refractive-index part having a higher refractive index than the low-refractive-index part.

Description

  The present invention relates to a laser module, a barcode scanner, and a photoelectric sensor.

  Conventionally, semiconductor lasers have been used as light sources for barcode scanners, photoelectric sensors, and the like. For example, Japanese Patent No. 3101397 (Patent Document 1) discloses a barcode scanner including a semiconductor laser, a collimator lens, an aperture, and a cylindrical lens. Further, in Patent Document 1, since the output characteristics of a semiconductor laser are elliptical due to the configuration of the element, the emitted light of the semiconductor laser is converted into parallel light by a collimator lens, shaped by an aperture, and then condensed by a cylindrical lens. Are emitted.

Japanese Patent No. 3101397

  However, as in Patent Document 1, when a semiconductor laser is used as a light source, light emitted from the semiconductor laser spreads, and thus it is necessary to collect the light with a lens. This lens system has a collimator lens, an aperture, a cylindrical lens, and the like, and is complicated. Therefore, there has been a problem of inhibiting miniaturization.

  Therefore, an object of the present invention is to provide a laser module, a barcode scanner, and a photoelectric sensor that can be miniaturized.

  The present inventor has found that the hindrance to the miniaturization of laser modules used in barcode scanners and photoelectric sensors is due to the complexity of the lens system. Therefore, as a result of intensive studies to simplify the lens system, the present inventor has completed the present invention.

  That is, the laser module of the present invention includes a photonic crystal laser element including a substrate, a first conductivity type cladding layer, a light emitting layer, a second conductivity type cladding layer, and a photonic crystal layer. . The first conductivity type cladding layer is formed on the substrate. The light emitting layer is formed on the first conductivity type cladding layer and generates light. The second conductivity type cladding layer is formed on the light emitting layer. The photonic crystal layer is formed between the first conductivity type cladding layer and the second conductivity type cladding layer, in the first conductivity type cladding layer, or in the second conductivity type cladding layer, And it has a low-refractive-index part and a high-refractive-index part whose refractive index is higher than a low-refractive-index part.

  According to the laser module of the present invention, the photonic crystal laser element is provided as the light source. The radiation angle of laser light generated from this photonic crystal laser element is narrow. For this reason, the lens used for condensing the generated light can be simplified. Therefore, size reduction can be achieved.

  Preferably, in the laser module, the low refractive index portions are arranged in a square lattice shape having a period of 184 nm or more and 239 nm or less. Preferably, in the laser module, the low refractive index portions are arranged in a triangular lattice shape having a period of 212 nm or more and 276 nm or less.

  Thereby, the light of the wavelength used suitably for a barcode scanner, a photoelectric sensor, etc. can be radiate | emitted.

  In the laser module, preferably, the photonic crystal laser element generates red or infrared light.

Thereby, it can use suitably for a barcode scanner, a photoelectric sensor, etc.
The barcode scanner of the present invention includes the laser module and a mirror. The mirror reflects light generated from the photonic crystal laser element.

  According to the barcode scanner of the present invention, since the laser module that can be miniaturized is provided, the barcode scanner can be miniaturized.

  The photoelectric sensor of the present invention includes the laser module and a light receiving unit. The light receiving unit receives light generated from the photonic crystal laser element.

  According to the photoelectric sensor of the present invention, since the laser module that can be reduced in size is provided, the photoelectric sensor can be reduced in size.

  As described above, according to the laser module, the barcode scanner, and the photoelectric sensor of the present invention, since the photonic crystal laser element that generates light having a narrow emission angle is provided, the size can be reduced.

It is a schematic diagram which shows schematically the laser module in Embodiment 1 of this invention. It is sectional drawing which shows schematically the photonic crystal laser element in Embodiment 1 of this invention. It is a top view which shows roughly the photonic crystal layer of the photonic crystal laser element in Embodiment 1 of this invention. It is a top view which shows roughly the photonic crystal layer of the photonic crystal laser element in Embodiment 1 of this invention. It is a schematic diagram which shows schematically the laser module in a comparative example. It is a perspective view which shows schematically the light source in a comparative example. It is sectional drawing which shows schematically the light source in a comparative example. It is a figure which shows the far-field image of the light which the light source in a comparative example generate | occur | produces. It is a figure which shows the far-field image of the light which the light source in a comparative example generate | occur | produces. It is a figure which shows the far-field image of the light which the photonic crystal laser element in Embodiment 1 of this invention generate | occur | produces. It is a perspective view which shows roughly the barcode scanner in Embodiment 2 of this invention. It is sectional drawing along the XII-XII line | wire in FIG. It is a schematic diagram which shows schematically the photoelectric sensor in Embodiment 3 of this invention. It is a schematic diagram which shows schematically the photoelectric sensor in the modification 1 of Embodiment 3 of this invention. It is a schematic diagram which shows roughly the photoelectric sensor in the modification 2 of Embodiment 3 of this invention. 1 is a cross-sectional view schematically showing a photonic crystal laser element of Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
First, with reference to FIGS. 1-4, the laser module 20 in Embodiment 1 of this invention is demonstrated. As shown in FIG. 1, the laser module 20 in the present embodiment includes a photonic crystal laser element 1 and a cover 21 that covers the photonic crystal laser element 1. The cover 21 has an opening 21 a in a region where light generated from the photonic crystal laser element 1 is emitted.

  As shown in FIG. 2, the photonic crystal laser element 1 includes a substrate 3, an n-type cladding layer 4, an active layer 5, p-type cladding layers 6 and 8, a photonic crystal layer 7, and a p-type electrode. 9 and an n-type electrode 10.

  As the substrate 3, for example, a GaAs (gallium arsenide) substrate can be used. The n-type cladding layer 4 is formed on the main surface 3 a of the substrate 3. The n-type cladding layer 4 is made of, for example, n-type AlGaInP and has a thickness of 1 μm.

  The active layer 5 is formed on the n-type cladding layer 4 and emits light by carrier injection. The active layer 5 has an MQW (Multiple-Quantum Well) structure in which, for example, a barrier layer made of undoped AlGaInP and a well layer made of GaInP are stacked. The active layer 5 may be made of a single semiconductor material.

  The p-type cladding layer 6 is formed on the active layer 5. The p-type cladding layer 6 is made of, for example, p-type AlGaInP and has a thickness of 1 μm.

  The photonic crystal layer (two-dimensional diffraction grating) 7 is formed on the p-type cladding layer 6 along the direction in which the main surface 3 a of the substrate 3 extends. The photonic crystal layer 7 will be described later.

  The p-type cladding layer 8 is formed on the active layer 5 and is made of, for example, p-type AlGaInP and has a thickness of 1 μm.

  The n-type cladding layer 4 and the p-type cladding layers 6 and 8 function as conductive layers through which carriers to be given to the active layer 5 are conducted. For this reason, the n-type cladding layer 4 and the p-type cladding layers 6 and 8 are provided so as to sandwich the active layer 5. The n-type cladding layer 4 and the p-type cladding layers 6 and 8 function as confinement layers that confine carriers (electrons and holes) and light in the active layer 5, respectively. That is, the n-type cladding layer 4, the active layer 5, and the p-type cladding layers 6 and 8 form a double heterojunction. For this reason, carriers contributing to light emission can be concentrated in the active layer 5. The n-type cladding layer 4 and the p-type cladding layers 6 and 8 preferably have a thickness of 1 μm or more in order to make the effect of confining carriers and light efficient.

  The p-type electrode 9 is formed on the p-type cladding layer 8. The p-type electrode 9 is formed at the center of the p-type cladding layer 8. The p-type electrode 9 is made of, for example, an alloy of gold (Au) and zinc (Zn). The p-type electrode 9 is preferably large enough to obtain a current density necessary for laser oscillation. For example, the planar shape has a size of about 100 μm square. Note that it is desirable to insert a contact layer such as GaAs between the p-type cladding layer 8 and the p-type electrode 9 so that an ohmic junction can be obtained.

  The n-type electrode 10 is formed on the back surface 3 b of the substrate 3. The n-type electrode 10 is a window opening electrode having an opening at the center. The n-type electrode 10 is made of, for example, an alloy of Au, Ge, and Ni.

  Here, the photonic crystal layer 7 will be described. The photonic crystal layer 7 has a low refractive index portion 2b made of a relatively low refractive index material and a high refractive index portion 2a made of a relatively high refractive index material, and the refractive index is periodically changed. Means a structure that changes.

  The photonic crystal layer 7 includes a high refractive index portion 2a made of a relatively high refractive index material and a low refractive index portion 2b made of a relatively low refractive index material. That is, the high refractive index portion 2a has a higher refractive index than the refractive index of the low refractive index portion 2b. In the photonic crystal layer 7, a high refractive index portion 2a and a low refractive index portion 2b are periodically arranged as viewed from the main surface 7a. The photonic crystal layer 7 has a thickness of 0.1 μm, for example.

The material constituting the high refractive index portion 2a of the present embodiment is made of, for example, AlGaInP having a refractive index of 3.3. The material constituting the low refractive index portion 2b is made of air having a refractive index of 1 filled in a hole formed in the high refractive index portion 2a. A large difference in refractive index between the materials constituting the high refractive index portion 2a and the low refractive index portion 2b is advantageous because a diffraction effect as a photonic crystal can be produced. The material constituting the low refractive index portion 2b is not particularly limited as long as it is lower than the refractive index of the material constituting the high refractive index portion 2a. For example, a dielectric such as silicon dioxide (SiO ₂ ) may be used. Alternatively, semiconductor materials having different compositions may be used.

  The high refractive index portion 2a and the low refractive index portion 2b (in this embodiment, the low refractive index portion 2b) are aligned in a fixed direction such as a square lattice shown in FIG. 3 or a triangular lattice shown in FIG.

  Note that the square lattice means that when the photonic crystal layer 7 is viewed from above (from the main surface 7a side), the low refractive index portion 2b (or high refractive index) is formed at an inclination angle of 90 ° with respect to the horizontal direction and the horizontal direction. This means that the rate part 2a) extends. That is, it means that the number of low refractive index portions 2b (or high refractive index portions 2a) adjacent to (or adjacent to) any low refractive index portion 2b (or high refractive index portion 2a) is four.

  The triangular lattice means that when the photonic crystal layer 7 is viewed from above (from the main surface 7a side), the low refractive index portion 2b (or the high refractive index portion) at a tilt angle of 60 ° with respect to the horizontal direction and the horizontal direction. 2a) extends. That is, it means that the number of low refractive index portions 2b (or high refractive index portions 2a) adjacent (or adjacent) to an arbitrary low refractive index portion 2b (or high refractive index portion 2a) is six.

  When the low refractive index portions 2b are arranged in a square lattice, the period (pitch) Λ that is the distance connecting the centers of the adjacent low refractive index portions 2b is preferably 184 nm or more and 239 nm or less. When the low refractive index portions 2b are arranged in a triangular lattice, the period (pitch) Λ, which is the distance connecting the centers of adjacent low refractive index portions 2b, is preferably 212 nm or more and 276 nm or less. In this case, light with a wavelength of 601 nm to 779 nm can be generated. For this reason, red light can be generated.

  In the present embodiment, the period Λ is in the above range in order to generate light of the above wavelength. The reason for this will be described below.

  The condition when the oscillated laser light is emitted only from the direction (upward in FIG. 2) perpendicular to the principal surface 7a of the photonic crystal layer 7 is that the first-order diffracted light is used. When the magnitude of the reciprocal lattice vector of the low refractive index portion 2b is equal to the wave number of the laser light, the second-order diffracted light is directed in the in-plane direction and amplified while resonating. At this time, since the first-order diffracted light is directed in a direction perpendicular to the main surface 7 a of the photonic crystal layer 7, light is emitted perpendicularly to the main surface 7 a of the photonic crystal layer 7. When the pattern of the photonic crystal layer 7 is a square lattice, the size of the reciprocal lattice vector is 2π / when the period of the low refractive index portion 2b (period Λ in FIG. 3) is Λ (unit: nm). Λ. For this reason, when the effective refractive index felt by the light in the laser resonator is n, light whose wavelength is equal to n × Λ (hereinafter also referred to as nΛ) satisfies this condition.

  In the present embodiment, in order to generate red or infrared light, the material of the high refractive index portion 2a of the photonic crystal layer 7 is AlGaInP, and the material of the low refractive index portion 2b is air. The effective refractive index felt by light is 3.26. Since the wavelength of red light is not less than 601 nm and not more than 779 nm, the period Λ satisfying 601 ≦ nΛ ≦ 779 is not less than 184 nm and not more than 239 nm.

When the pattern of the photonic crystal layer 7 is a triangular lattice, when the period of the low refractive index portion 2b (period Λ in FIG. 4) is Λ, the size of the reciprocal lattice vector is (2π / Λ) · { 2 / (3) ^1/2 }. Therefore, light having a wavelength equal to {(3) ^1/2 n / 2} times the period Λ, that is, light having a wavelength of n × Λ × {(3) ^1/2 / 2} satisfies this condition.

In the present embodiment, in order to generate red or infrared light, the material of the high refractive index portion 2a of the photonic crystal layer 7 is AlGaInP, and the material of the low refractive index portion 2b is air. The effective refractive index felt by light is 3.26. Since the wavelength of red light is not less than 601 nm and not more than 779 nm, the period Λ satisfying 601 ≦ Λn ((3) ^1/2 / 2) ≦ 779 is not less than 212 nm and not more than 276 nm.

  In the present embodiment, the period Λ is controlled in order to extract red light. However, the period Λ can be similarly controlled when infrared light is extracted. The wavelength of infrared light is 780 nm or more and 1600 nm or less. Therefore, the low refractive index portion 2b is preferably arranged in a square lattice shape having a period Λ of 244 nm or more and 500 nm or less, or in a triangular lattice shape having a period Λ of 281 nm or more and 577 nm or less. .

  Then, with reference to FIGS. 1-4, the manufacturing method of the laser module 20 in this Embodiment is demonstrated.

  First, as shown in FIG. 2, a substrate 3 is prepared. Next, the n-type cladding layer 4 is formed on the main surface 3 a of the substrate 3. In this step, the n-type cladding layer 4 made of n-type AlGaInP and having a thickness of 1 μm is formed by, for example, MOCVD (Metal Organic Chemical Vapor Deposition).

  Next, an active layer 5 that generates light is formed on the n-type cladding layer 4. In this step, the active layer 5 having a multiple quantum well structure including a barrier layer made of undoped AlGaInP and a well layer made of GaInP is formed by, for example, MOCVD.

  Next, a p-type cladding layer 6 is formed on the active layer 5. In this step, the p-type cladding layer 6 made of p-type AlGaInP and having a thickness of 1 μm is formed by MOCVD, for example.

  Next, as shown in FIGS. 2 to 4, a photonic crystal layer 7 is formed on the p-type cladding layer 6. In the present embodiment, the photonic crystal layer 7 in which the low refractive index portion 2b is air is formed. Specifically, the following processing is performed.

  First, a semiconductor layer that is a material to be the high refractive index portion 2 a is formed on the p-type cladding layer 6. Thereafter, a resist having a pattern is formed on the semiconductor layer by using a photolithography method. In this resist, an opening pattern is formed on a region where a hole constituting the low refractive index portion 2b of the photonic crystal layer 7 shown in FIGS. 2 to 4 is to be formed. The planar shape of the opening pattern is the same as the planar shape of the hole, and can be, for example, a circular shape. This opening pattern is preferably formed in a square lattice shape having a period Λ of 184 nm or more and 239 nm or less, or a triangular lattice shape having a period Λ of 212 nm or more and 276 nm or less in consideration of the wavelength of emitted light. Next, using the resist as a mask, the semiconductor layer is partially removed by etching to form holes. Thereafter, the resist is removed. Thereby, the photonic crystal layer 7 having the high refractive index portion 2a made of a semiconductor and the low refractive index portion 2b made of air surrounded by a hole can be formed.

  Next, a p-type cladding layer 8 is formed on the photonic crystal layer 7. In this step, a p-type cladding layer 8 made of p-type AlGaInP and having a thickness of 1 μm is formed, for example, by MOCVD. By forming the p-type cladding layer 8, the low refractive index portion 2 b of the photonic crystal layer 7 is surrounded by the hole and the p-type cladding layer 8.

  Next, a p-type electrode 9 is formed on the p-type cladding layer 8. In this step, for example, Au, Zn, and Au are vapor-deposited in this order on the p-type cladding layer 8 by, for example, vapor deposition, and heat treatment for alloying is performed to form the p-type electrode 9. . It is desirable to form a contact layer such as GaAs between the p-type cladding layer 8 and the p-type electrode 9 so that an ohmic junction can be obtained.

  Next, the n-type electrode 10 is formed on the back surface 3 b of the substrate 3. In this step, for example, Au—Ge, Ni, and Au are sequentially laminated on the back surface of the substrate 3 by a vapor deposition method, and heat treatment for alloying is performed. Through the above steps, the photonic crystal laser element 1 can be manufactured.

  Next, as shown in FIG. 1, the photonic crystal laser element 1 is accommodated in the cover 21. By performing the above steps, the laser module 20 shown in FIG. 1 can be manufactured.

  The photonic crystal laser element 1 according to the present embodiment has been described by taking the structure in which the electrodes are formed above and below as an example. However, the photonic crystal laser element of the present invention is not limited to this structure. A structure in which the mold electrode 9 and the n-type electrode 10 are formed on the upper side (the side opposite to the substrate 3) can also be applied.

  Here, as the laser module 20 of the present embodiment, the structure including the cover 21 has been described as an example. However, the structure is not particularly limited to this structure, and the laser module of the present invention can be used instead of the cover 21 or A member such as a base may be provided together with the cover 21. When the base is used, the laser module includes a base and a photonic crystal laser element 1 arranged on the base. That is, the laser module further includes a member that is not covered by the base.

  Next, operation | movement of the laser module 20 of this Embodiment is demonstrated using FIGS. 1-4.

  In the photonic crystal laser element 1, when a positive voltage is applied to the p-type electrode 9 and a negative voltage is applied to the n-type electrode 10, holes are injected from the p-type cladding layers 6 and 8 into the active layer 5. Electrons are injected from 4 into the active layer 5. When holes and electrons (carriers) are injected into the active layer 5, carrier recombination occurs and light is generated. The wavelength of the generated light is defined by the band gap of the semiconductor layer included in the active layer 5.

  Light generated in the active layer 5 is confined in the active layer 5 by the n-type cladding layer 4 and the p-type cladding layers 6 and 8, but part of the light reaches the photonic crystal layer 7 as evanescent light. When the wavelength of the evanescent light reaching the photonic crystal layer 7 and the predetermined period of the photonic crystal layer 7 coincide, the light repeats diffraction at the wavelength corresponding to the period, and a standing wave is generated. And phase conditions are defined. The light whose phase is defined by the photonic crystal layer 7 is fed back to the light in the active layer 5 to generate a standing wave. This standing wave satisfies the light wavelength and phase conditions defined in the photonic crystal layer 7.

  Such a phenomenon can occur in the region around the p-type electrode 9 and in the vicinity thereof because the active layer 5 and the photonic crystal layer 7 are two-dimensionally widened. When a sufficient amount of light is accumulated in this state, light L having a uniform wavelength and phase condition is stimulated and emitted from a direction perpendicular to the main surface 7a of the photonic crystal layer 7 (upward in FIG. 1). . The generated light L is emitted from the opening 21 a of the cover 21.

  Next, the effects of the laser module 20 in the present embodiment will be described in comparison with the laser module 100 of the comparative example shown in FIGS.

  The laser module 100 of the comparative example shown in FIG. 5 includes a semiconductor laser element 110, a collimator lens 101, and a condenser lens 102. The semiconductor laser element 110 is used as a light source instead of the photonic crystal laser element 1. The semiconductor laser element 110 is an edge-emitting laser 110a shown in FIG. 6, a surface emitting laser 110b called VCSEL (Vertical Cavity Surface Emitting Laser) shown in FIG.

  An edge-emitting laser 110a shown in FIG. 6 includes, for example, a substrate 111, an n-type cladding layer 112 formed on the substrate 111, an active layer 113 formed on the n-type cladding layer 112, and an active layer 113. A p-type cladding layer 114 formed on the p-type cladding layer 114, an electrode 115 formed on the p-type cladding layer 114, and an electrode 116 formed on the back side of the substrate 111. As shown in FIG. 6, the edge emitting laser 110a generates light in a direction parallel to each layer.

  The surface emitting laser 110b shown in FIG. 7 includes a substrate 111, a DBR (Distributed Bragg Reflection) mirror 118 formed on the substrate 111, an active layer 113 formed on the DBR mirror 118, and an active layer. 113, an oxide film 119 having an opening, a DBR mirror 120 which is an opening of the oxide film 119 and formed on the active layer 113, and an opening formed on the DBR mirror 120. And the electrode 116 formed on the back surface side of the substrate 111. As shown in FIG. 7, the surface emitting laser 110 b generates light from an opening provided in the electrode 115 on the surface side of the substrate 111.

  It can be seen that the far-field image of the light generated by the edge-emitting laser 110a shown in FIG. 6 spreads as shown in FIG. It can be seen that the far-field image of the light generated by the surface emitting laser 110b shown in FIG. 7 also spreads as shown in FIG. For this reason, when the semiconductor laser device 110 such as the edge-emitting laser 110a or the surface-emitting laser 110b is provided, at least the collimator lens 101 and the condensing lens are used to collect the light generated from the semiconductor laser device 110. 102 must be used. Therefore, in the laser module 100 of the comparative example, there is a problem that the lens system becomes complicated and the miniaturization cannot be achieved.

  On the other hand, the laser module 20 in the present embodiment uses the photonic crystal laser element 1 as a light source. The laser light of the photonic crystal laser element 1 is emitted from a direction perpendicular to the main surface 7a of the photonic crystal layer 7 due to the diffraction effect by the photonic crystal layer 7 as described above. In addition, resonance in the in-plane direction of the photonic crystal layer 7 occurs over the entire surface of the photonic crystal layer 7, and as a result, the area of the light emitting portion (emission portion) can be increased. Thereby, the radiation angle of the light emitted from the photonic crystal laser element 1 can be made very narrow. This can also be seen from the fact that the far-field image of the light generated by the photonic crystal laser element 1 is very narrow and less than 1 ° as shown in FIG. Thus, unlike the laser module 100 of the comparative example shown in FIG. 5, the laser module 20 according to the present embodiment does not need to focus using a lens as shown in FIG. By using about one lens thinner than the lens of the comparative example, it is possible to cope with obtaining a desired beam pattern, condensing diameter, focal depth, imaging position, and the like. Thereby, the lens system can be simplified. Therefore, the laser module 20 in the present embodiment can be reduced in size and the cost can be reduced.

  In particular, when the low refractive index portion 2b is arranged in a square lattice shape having a period of 184 nm or more and 239 nm or less, or the low refractive index portion 2b is arranged in a triangular lattice shape having a period of 212 nm or more and 276 nm or less. In this case, red laser light can be emitted. For this reason, the laser module 20 is suitably used for a general photoelectric sensor, a barcode scanner, and the like as a red laser beam.

  In the photonic crystal laser element 1 of the first embodiment, the photonic crystal layer 7 is disposed between the n-type cladding layer 4 and the p-type cladding layer 8, but the present invention is not limited to this. The photonic crystal layer 7 may be formed in either the n-type cladding layer 4 or the p-type cladding layers 6 and 8 regardless of the material.

  In addition, the photonic crystal layer 7 has been described by taking as an example a structure having a high refractive index portion 2a made of a semiconductor and a low refractive index portion 2b made of at least one of air and a dielectric, but the present invention is particularly limited to this. Not. The high refractive index portion 2a and the low refractive index portion 2b need only have a difference in refractive index, and may be made of semiconductors of different materials.

(Embodiment 2)
With reference to FIG. 11 and FIG. 12, the barcode scanner 30 in this Embodiment is demonstrated. The barcode scanner 30 in the present embodiment is a laser system.

  As shown in FIGS. 11 and 12, the barcode scanner 30 includes the laser module 20, the mirrors 31 and 32, the polygon mirror 33, the motor 34, the condenser lens 35, and the photodiode 36 of the first embodiment. And housings 37 and 38. The mirrors 31 and 32 reflect light generated from the photonic crystal laser element of the laser module 20. The polygon mirror 33 irradiates the barcode B with the light L from the mirrors 31 and 32. The motor 34 drives the polygon mirror 33. The condensing lens 35 condenses the light reflected from the barcode B. The photodiode 36 reads the reflected light collected by the condenser lens 35. The housing 37 can accommodate and hold the laser module 20 therein. The housing 38 houses the mirrors 31 and 32, the polygon mirror 33, the motor 34, the condenser lens 35, and the photodiode 36 therein.

  The barcode scanner 30 may further include a galvanometer mirror. In this case, since the light L can be irradiated vertically and horizontally, it is possible to deal with a two-dimensional barcode.

  Next, the operation of the barcode scanner 30 in the present embodiment will be described. As shown in FIGS. 11 and 12, light is generated from the photonic crystal laser element of the laser module 20. This light is reflected by the mirrors 31 and 32 toward the polygon mirror 33. One light L is reflected by the polygon mirror 33 that is operated by the motor 34 and is shaken to the left and right to irradiate the barcode B. Thus, by irradiating the barcode B with the light generated from the laser module 20 to the left and right, each light L can be scanned as indicated by the arrow A. Each light L applied to the barcode B is reflected by the barcode B, and the reflected light is collected (received) by the condenser lens 35. The received light is transmitted to the photodiode 36, and the barcode B is read by the reflected light.

  The barcode scanner 30 according to the present embodiment uses the laser module 20 according to the first embodiment. Since the emission angle of the light generated from the photonic crystal laser element is narrow, the lens used for condensing the generated light is simplified. For this reason, since the laser module 20 can be downsized, the barcode scanner 30 can be downsized.

  As described above, according to the barcode scanner 30 in the present embodiment, the barcode B at a distant position can be read, and the barcode scanner 30 can be downsized.

(Embodiment 3)
A photoelectric sensor 40 in the present embodiment will be described with reference to FIG. The photoelectric sensor 40 in the present embodiment is a transmissive type.

  The photoelectric sensor 40 includes the laser module 20 of the first embodiment, a projector 41, a light receiving unit 42, and a light receiver 43. The laser module 20 is a light projecting unit. The projector 41 houses the laser module 20 therein. The light receiving unit 42 receives the transmitted light T transmitted through the detection object D out of the light L generated from the laser module 20 of the projector 41. The light receiver 43 accommodates the light receiving unit 42 therein. The photo detector 43 may use a phototube. The photoelectric sensor 40 in this case is a photoelectric tube sensor.

  Subsequently, the operation of the photoelectric sensor 40 in the present embodiment will be described. As shown in FIG. 13, light L is generated from the photonic crystal laser element of the laser module 20 toward the detection object D. A part of the light L irradiated to the detection object D passes through the detection object D. The transmitted light T reaches the light receiving unit 42 in the light receiver 43. Since the light L is blocked by the detection object D, the amount of transmitted light T reaching the light receiving unit 42 varies from the amount of light L. The light receiving unit 42 detects this change, converts it into an electrical signal, and outputs it.

(Modification 1)
As shown in FIG. 14, the photoelectric sensor 50 according to the first modification of the present embodiment is different from the photoelectric sensor 40 according to the third embodiment in that it is a regression reflection type.

  Specifically, the photoelectric sensor 50 of Modification 1 includes a laser module 20, a light receiving unit 42, a light projector / receiver 51, and a regression reflector 52. The laser module 20 and the light receiving unit 42 are accommodated in the light projector / receiver 51. The retroreflection plate 52 reflects the transmitted light T transmitted through the detection object D out of the light generated from the laser module 20.

  Subsequently, the operation of the photoelectric sensor 50 of the first modification will be described. As shown in FIG. 14, light L is generated from the photonic crystal laser element of the laser module 20 toward the detection object D. A part of the light L irradiated to the detection object D is reflected by the detection object D. The reflected light R reaches the light receiving unit 42 in the light projector / receiver 51. Further, the remaining part of the light L applied to the detection object D passes through the detection object D. The transmitted light T is reflected by the return reflection plate 52, and the reflected light partially transmits the detection object D and reaches the light receiving unit 42 in the light projecting / receiving device 51. When the light L is reflected or blocked by the detection object D, the amount of the reflected light R that reaches the light receiving unit 42 changes from the amount of the light L. The light receiving unit 42 detects this change, converts it into an electrical signal, and outputs it.

(Modification 2)
As shown in FIG. 15, the photoelectric sensor 60 of Modification 2 of the present embodiment is different from the photoelectric sensor 40 of Embodiment 3 in that it is a diffuse reflection type.

  Specifically, the photoelectric sensor 60 of Modification 2 includes the laser module 20, a light receiving unit 42, and a light projecting / receiving device 61. The laser module 20 and the light receiving unit 42 are accommodated in the light projector / receiver 61.

  Next, the operation of the photoelectric sensor 60 of Modification 2 will be described. As shown in FIG. 15, light L is generated from the photonic crystal laser element of the laser module 20 toward the detection object D. A part of the light L irradiated to the detection object D is reflected by the detection object D. The reflected light R reaches the light receiving unit 42 in the light projector / receiver 61. Further, the remaining part of the light L applied to the detection object D passes through the detection object D. When L is reflected or blocked by the detection object D, the amount of reflected light R reaching the light receiving unit 42 changes from the amount of light L. The light receiving unit 42 detects this change, converts it into an electrical signal, and outputs it.

  In the present embodiment and its modifications 1 and 2, the laser module 20 in the first embodiment is used. Since the emission angle of the light generated from the photonic crystal laser element is narrow, the lens used for condensing the generated light is simplified. For this reason, since the laser module 20 can be reduced in size, the photoelectric sensors 40, 50, 60 can be reduced in size.

  In addition, since the radiation angle of light generated from the photonic crystal laser element is narrow, the spatial resolution can be increased. For this reason, the photoelectric sensors 40, 50, and 60 capable of detecting minute objects and detecting positions with high accuracy can be realized.

  As described above, according to the photoelectric sensors 40, 50, and 60 in the present embodiment and the first and second modifications thereof, the detection object can be detected and the photoelectric sensors 40, 50, and 60 can be downsized. Yes.

In this example, the wavelength of light generated by the photonic crystal laser element was examined.
In this example, as shown in FIG. 16, a photonic crystal surface emitting laser having a wavelength of around 650 nm was fabricated using AlGaInP for the active layer 5.

  Specifically, an n-type cladding layer 4 made of n-type AlGaInP, an active layer 5 and a p-type cladding layer 6 made of p-type AlGaInP were grown in this order on the substrate 3 made of GaAs by epitaxial growth by MOCVD. .

  Next, a layer to be the high refractive index portion 2a was grown on the p-type cladding layer 6 by MOCVD. Then, using the resist patterned by the electron beam lithography apparatus as a mask, a low-refractive index portion 2b (pattern) of the photonic crystal layer 7 is produced by digging a circular hole by dry etching using chlorine gas with a reactive ion etching apparatus. did. As a result, a high refractive index portion 2a made of AlGaInP and a low refractive index portion 2b made of air were formed. The refractive index of air was 1, and the refractive index of AlGaInP was 3.3.

  Further, epitaxial growth was performed by MOCVD to grow a p-type cladding layer 8 and a p-type contact layer 11. Finally, an n-type electrode 10 made of an alloy of Au, Ge, and Ni is deposited on the n-side, and a p-type electrode 9 made of an alloy of Au and Zn is deposited on the p-side, and mounted on the stem 12 for photo A nick crystal laser element was obtained. A plurality of photonic crystal laser elements were manufactured by changing the arrangement of the low refractive index portion 2b and the period Λ in various ways.

  Table 1 below shows the results of the period Λ of the low refractive index portion 2b of the photonic crystal layer in the plurality of photonic crystal laser elements and the wavelength (operating wavelength) of the generated laser light.

  As shown in Table 1, when the photonic crystal laser element is operated at a wavelength close to red of 601 nm to 779 nm, it is 184 nm to 239 nm for a square lattice pattern, and 212 nm or more for a triangular lattice pattern. It was found that the period Λ needs to be in the range of 276 nm or less.

  As described above, according to the present embodiment, when the low refractive index portion is arranged in a square lattice shape having a period of 184 nm or more and 239 nm or less, or the triangular grating having a low refractive index portion having a period of 212 nm or more and 276 nm or less. It was confirmed that light of a red wavelength can be generated when arranged in a shape.

  In this example, the effect of providing the photonic crystal laser element in the laser module was examined.

  Specifically, each photonic crystal laser element of Example 1 was placed in the barcode scanner of the second embodiment and the photoelectric sensor of the third embodiment. At this time, no lens was arranged in the laser module.

  As a result, the barcode scanner and the photoelectric sensor equipped with the laser module including the plurality of photonic crystal laser elements of Example 1 were able to operate even when no lens was arranged on the laser module.

  As described above, according to this example, it was confirmed that the lens can be omitted by using the laser module including the photonic crystal laser element. It was also confirmed that the laser module equipped with the photonic crystal laser element can be miniaturized.

  Furthermore, it was confirmed that a barcode scanner and a photoelectric sensor equipped with a laser module equipped with a photonic crystal laser element can be downsized.

  Although the embodiments and examples of the present invention have been described above, it is also planned from the beginning to appropriately combine the features of the embodiments and examples. The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  DESCRIPTION OF SYMBOLS 1 Photonic crystal laser element, 2a High refractive index part, 2b Low refractive index part, 3 board | substrate, 3a, 7a main surface, 3b back surface, 4 n-type cladding layer, 5 active layer, 6,8 p-type cladding layer, 7 Photonic crystal layer, 9 p-type electrode, 10 n-type electrode, 11 p-type contact layer, 12 stem, 20 laser module, 21 cover, 21a opening, 30 barcode scanner, 31, 32 mirror, 33 polygon mirror, 34 Motor, 35 Condenser lens, 36 Photodiode, 37, 38 Case, 40, 50, 60 Photoelectric sensor, 41 Emitter, 42 Light receiver, 43 Light receiver, 51, 61 Emitter / receiver, 52 Retroreflective plate, B bar Code, D sensing object, L light, R reflected light, T transmitted light.

Claims (6)

  A substrate, a first conductive type cladding layer formed on the substrate, a light emitting layer formed on the first conductive type cladding layer and generating light, and a first conductive layer formed on the light emitting layer; A two-conductivity-type cladding layer, and between the first-conductivity-type clad layer and the second-conductivity-type clad layer, in the first-conductivity-type clad layer, or in the second-conductivity-type clad layer. A laser module comprising a photonic crystal laser element including a photonic crystal layer formed in any of the above and having a low refractive index portion and a high refractive index portion having a higher refractive index than the low refractive index portion.   The laser module according to claim 1, wherein the low refractive index portions are arranged in a square lattice shape having a period of 184 nm or more and 239 nm or less.   The laser module according to claim 1, wherein the low refractive index portions are arranged in a triangular lattice shape having a period of 212 nm or more and 276 nm or less.   The laser module according to claim 1, wherein the photonic crystal laser element generates the red or infrared light. A laser module according to claim 1;
A barcode scanner comprising: a mirror for reflecting the light generated from the photonic crystal laser element. A laser module according to claim 1;
A photoelectric sensor comprising: a light receiving portion that receives the light generated from the photonic crystal laser element.