JP2006091285A - Light emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small light emitting apparatus at low cost and with a simple structure. <P>SOLUTION: This light emitting apparatus is equipped with a surface emitting array 1 including a plurality of surface emitting parts 3, a diffractive optical element array 4 including a plurality of diffractive optical elements 6 that converge the outgoing light of the plurality of surface emitting parts 3 on one point, and an optical fiber 7 that receives the light converged by the diffractive optical element array 4 at one end to make it exit from the other end. Consequently, compared with the conventional system of converging light with a plurality of optical fibers, price reduction of the apparatus, simplification of the structure and the miniaturization of the apparatus can be achieved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting device, and more particularly to a high output light emitting device.

  Conventionally, the output of a semiconductor laser device has been increased, but there is a limit. However, strong laser light can be easily obtained by bundling the emitted light of a plurality of semiconductor laser elements into one.

  That is, as shown in FIG. 6, a plurality of semiconductor laser elements 31 are used, and the emitted light of each semiconductor laser element 31 is collimated by a collimator lens 32 and introduced into one end of an optical fiber 33. If light from the other end is introduced into one end of one optical fiber 34, strong laser light can be obtained from the other end of the optical fiber 34.

As shown in FIG. 7, the light emitted from the surface light emitting array 41 is collimated by a collimator lens array 42 to produce a planar light source (see, for example, Patent Document 1). If light is introduced into one end and light from the other end of the optical fiber array 43 is introduced into one end of one optical fiber 44, strong laser light can be obtained from the other end of the optical fiber 44.
JP 2002-49326 A

  However, in the method using a plurality of semiconductor laser elements 31, since it is necessary to adjust the optical axis for each set of the semiconductor laser element 31, the collimator lens 32, and the optical fiber 33, the apparatus price increases and the apparatus configuration is increased. There was a problem of becoming complicated.

  Further, in the method using the surface light emitting array 41, the pitch of the surface light emitting portions in the surface light emitting array 41 cannot be made smaller than the diameter of the optical fiber in the optical fiber array 43, and the device size cannot be reduced. There's a problem. In addition, the accuracy of the optical fiber array 43 is limited.

  Therefore, a main object of the present invention is to provide a small light emitting device with a low cost and a simple configuration.

Means and effects for solving the problem

  A light-emitting device according to the present invention includes a surface-emitting array including a plurality of surface-emitting units, an optical element that collects light emitted from the plurality of surface-emitting units at one point, and one end of which is condensed by the optical element. And an optical fiber that receives light and emits it from the other end. Therefore, since the emitted light from the surface emitting array is collected by one optical element, it can be easily mounted compared to the conventional case where the light is collected by a plurality of optical fibers, the cost of the apparatus is reduced, and the configuration is simple. Can be achieved. Further, the pitch of the surface light emitting portions in the surface light emitting array can be made smaller than the diameter of the optical fiber, and the device can be miniaturized.

  Preferably, the optical element is provided corresponding to each of the plurality of surface light emitting units, and each includes a plurality of diffractive optical elements that allow the emitted light of the corresponding surface light emitting unit to enter one end of the optical fiber. An array. In this case, the optical element can be reduced in size and thickness.

  Preferably, the diffractive optical element is made of a material including at least one selected from glass, resin, SiC, GaN, AlN, LiNbO, LiTaO, diamond, ZnO, sapphire, DLC, and a photopolymer. In this case, a high diffraction effect can be obtained and the diffractive optical element can be thinned.

  Preferably, the optical element is a photonic crystal. In this case, the optical element can be reduced in size and thickness.

  Preferably, the photonic crystal is formed of a material including at least one selected from Si, InP, GaAs, GaN, AlN, and SiC. In this case, it can be processed by a semiconductor process, and a high refractive index can be obtained.

  Preferably, the surface emitting array is formed by laminating at least a nitride semiconductor layer on a conductive gallium nitride substrate. In this case, since high thermal conductivity can be obtained, the heat of the surface light emitting portion can be sufficiently dissipated, and the surface light emitting portions can be arrayed with high density. Further, since the thermal expansion coefficients of the substrate and each layer are close, unnecessary stress is not applied.

  Preferably, each surface emitting unit is a surface emitting laser. In this case, the output of the surface light emitting unit can be increased.

[Embodiment 1]
FIG. 1 is a diagram showing a configuration of a light emitting device according to Embodiment 1 of the present invention. In FIG. 1, the light emitting device includes a surface light emitting array 1, a diffractive optical element array 4, and an optical fiber 7. The surface light emitting array 1 includes a quadrangular substrate 2 and 16 surface light emitting units 3 arranged in a plurality of rows and a plurality of columns (here, 4 rows and 4 columns) on the surface thereof.

  The surface emitting array 1 is preferably formed by laminating at least a nitride semiconductor layer on the surface of a conductive gallium nitride substrate which is the substrate 2. Thereby, high heat dissipation can be obtained, and the heat generated when the surface light emitting unit 3 emits light can be efficiently dissipated. Moreover, generation | occurrence | production of the crack resulting from the difference of the thermal expansion coefficient of a board | substrate and each layer can be suppressed. The surface emitting unit 3 is preferably a surface emitting laser. Thereby, a high output can be obtained.

  The diffractive optical element array 4 is formed by forming 16 diffractive optical elements 6 on the surface of a translucent substrate 5. Sixteen diffractive optical elements 6 are provided corresponding to the sixteen surface light emitting sections 3, respectively. Each diffractive optical element 6 causes the light emitted from the corresponding surface light emitting unit 3 to enter one end of the optical fiber 7.

  The diffractive optical element 6 includes a diffraction grating layer. In the diffraction grating layer, a first local region having a relatively small refractive index (or film thickness) and a second local region having a relatively large refractive index (or film thickness) are in a predetermined cycle. It is formed alternately. As a method of forming a diffractive optical element, a method of irradiating an energy beam in a periodic pattern after forming a translucent layer with a material whose refractive index changes by irradiation of the energy beam, or utilizing photolithography and etching. There is a method for processing a light-transmitting layer.

  A diffraction phenomenon occurs due to the phase difference between the light passing through the first local region and the light passing through the second local region. The diffraction angle of the diffractive optical element 6 can be adjusted by adjusting the ratio of the refractive indexes (or film thicknesses) of the first and second local regions. By increasing the diffraction angle of the diffractive optical element 6 having a large distance from the center of the diffractive optical element array 4 and decreasing the diffraction angle of the diffractive optical element 6 having a small distance from the center of the diffractive optical element array 4, Light emitted from the surface light emitting unit 3 is collected at the center of one end of the optical fiber 7.

  The diffractive optical element 6 is made of a material including at least one selected from glass, resin, SiC, GaN, AlN, LiNbO, LiTaO, diamond, ZnO, sapphire, DLC (diamond-like carbon: diamond-like carbon), and a photopolymer. Is formed. Thereby, a high diffraction effect can be obtained and the diffractive optical element 6 can be made thin.

  The 16 laser beams incident on one end of the optical fiber 7 are bundled into one laser beam by the optical fiber 7 and emitted from the other end of the optical fiber 7.

  In this Embodiment 1, since the emitted light of the surface emitting array 1 is condensed by the diffractive optical element array 4, mounting is easier than in the conventional case where the light is condensed by the plurality of optical fibers 33 and the optical fiber array 43. Therefore, it is possible to reduce the price of the apparatus and simplify the configuration. Further, the pitch of the surface light emitting portions 3 in the surface light emitting array 1 can be made smaller than the diameter of the optical fiber 7, and the apparatus can be miniaturized.

[Embodiment 2]
FIG. 2 is a diagram showing a configuration of a light emitting device according to Embodiment 2 of the present invention. Referring to FIG. 2, this light emitting device is different from the light emitting device of FIG. 1 in that diffractive optical element 4 is replaced with photonic crystal 10.

  As shown in FIG. 3, the photonic crystal 10 includes a first layer in which columnar members 11 extending in a first direction are arranged at a predetermined period, and a second direction orthogonal to the first direction. An optical path through which light can pass is formed in the bulk of a three-dimensional periodic structure in which the existing columnar members 12 are alternately arranged with second layers arranged with a predetermined period. The light emitted from the 16 surface emitting units 3 passes through an optical path formed in the photonic crystal 10 and is emitted from the center point of the photonic crystal 10 to one end of the optical fiber 7.

  The photonic crystal 10 is formed of a material including at least one selected from Si, InP, GaAs, GaN, AlN, and SiC. Thereby, it can process by a semiconductor process and can obtain a high refractive index.

  Next, a method for manufacturing the light emitting device will be specifically described. First, a surface emitting laser array using a conductive gallium nitride substrate was prepared as the surface emitting array 1. The surface emitting laser array has 10 rows and 10 columns of light emitting portions (surface emitting portions 3). The pitch of the light emitting parts is 200 μm. The wavelength of the emitted light is 405 nm, and the light output per light emitting part is 5 mW. This surface emitting laser array is formed so that all the light emitting portions can be energized from the electrode at the end of the array substrate in order to join the photonic crystal 10 to the light emitting surface.

As the photonic crystal material, GaN having a refractive index n = 2.4 was selected. A SiO ₂ film having a thickness of 130 nm was formed on a GaAs substrate by sputtering deposition, and lines and spaces having a pitch of 119 nm were formed by photolithography and dry etching. Next, GaN was deposited to a thickness of 119 nm by MOCVD. However, GaN does not grow on the SiO ₂ film. Next, the SiO ₂ film was removed, and as shown in FIG. 4A, a member in which only the GaN line L remained on the GaAs substrate was produced.

  At this time, GaN does not remain in the light receiving path A for receiving the emitted light of the surface emitting laser array and in one place, that is, not the fixed line L and the space S but the line A specially designed mask for photolithography was used so that a part where L was partially lost was formed. In FIG. 4A, only one light guide path A is shown for simplification of the drawing. Using this technique, as shown in FIGS. 4A to 4D, GaN-attached GaAs substrates for the number of layers (four layers in the figure) necessary for condensing with a photonic crystal were prepared and prepared. .

  Next, the GaN-attached GaAs substrate is introduced into the ultrahigh vacuum chamber in order from the upper layer, the GaN bonding surface is cleaned with nitrogen plasma, the GaN surface is aligned as it is, and high temperature and high pressure are applied, and bonding is performed in the manner of wafer bonding. did. After bonding, only the lower GaAs was removed so that the upper GaAs remained. Next, a member obtained by joining the third and fourth GaN-attached GaAs substrates from the top in the above-described procedure was joined to the first and second layer members. FIG. 5A is a front view of the photonic crystal formed as described above, and FIG. 5B is a cross-sectional view taken along the line VB-VB in FIG. The odd-numbered layer lines L and the even-numbered layer lines L are arranged orthogonally. The laser light emitted from the light emitting portion of the surface emitting laser array is guided to the emission port through the light guide path A formed by the missing portion of the line L.

  As described above, a three-dimensional lattice-like photonic crystal having a necessary thickness was produced. Thereafter, the surface emitting laser array and the produced three-dimensional lattice-like photonic crystal were positioned so that the light emitting portion of the surface emitting laser array was aligned with the light guide portion of the photonic crystal, and joined by the above-described method. When the fabricated surface emitting laser array with a photonic crystal was oscillated, light was emitted from one emitting portion of the photonic crystal. The output power of the emitted light was about 480 mW.

  In the second embodiment, the same effect as in the first embodiment can be obtained.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the structure of the light-emitting device by Embodiment 1 of this invention. It is a figure which shows the structure of the light-emitting device by Embodiment 2 of this invention. It is a figure which shows the structure of the photonic crystal shown in FIG. It is a figure which shows the preparation methods of the photonic crystal shown in FIG. It is another figure which shows the preparation methods of the photonic crystal shown in FIG. It is a figure which shows the structure of the conventional light-emitting device. It is a figure which shows the structure of the other conventional light-emitting device.

Explanation of symbols

  1,41 surface emitting array, 2 substrate, 3 surface emitting unit, 4 diffractive optical element array, 5 translucent substrate, 6 diffractive optical element, 7, 33, 34, 44 optical fiber, 10 photonic crystal, 11, 12 Columnar member, L line, S space, A light guide path, 31 semiconductor laser, 32 collimator lens, 42 collimator lens array, 43 optical fiber array.

Claims (7)

A surface emitting array including a plurality of surface emitting portions;
An optical element for condensing the light emitted from the plurality of surface light emitting units at one point;
A light emitting device comprising: an optical fiber having one end receiving light collected by the optical element and emitting the light from the other end.   Each of the optical elements is provided corresponding to the plurality of surface light emitting units, and each includes a plurality of diffractive optical elements that allow the light emitted from the corresponding surface light emitting units to enter one end of the optical fiber. The light-emitting device according to claim 1, which is an array.   The diffractive optical element is formed of a material including at least one selected from glass, resin, SiC, GaN, AlN, LiNbO, LiTaO, diamond, ZnO, sapphire, DLC, and a photopolymer. The light-emitting device of description.   The light emitting device according to claim 1, wherein the optical element is a photonic crystal.   The light emitting device according to claim 4, wherein the photonic crystal is formed of a material including at least one selected from Si, InP, GaAs, GaN, AlN, and SiC.   The light emitting device according to claim 1, wherein the surface emitting array is formed by laminating at least a nitride semiconductor layer on a conductive gallium nitride substrate.   The light emitting device according to any one of claims 1 to 6, wherein each surface emitting unit is a surface emitting laser.

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