JP2006343712A - Light source device, scanning display device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain high-speed modulation with respect to a light source device which is constituted by combining a vertical external cavity surface emitting laser (VECSEL) having an external resonance mirror, and a wavelength conversion element. <P>SOLUTION: The light source device 50 is provided with: the VECSEL 10 composed of an light emission part 20 and the external resonance mirror 7 which makes light beams emitted from the light emission part 20 to resonate; and the wavelength conversion element 8 which wavelength-converts light beams transmitted by the external resonance mirror 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light source device, a scanning display device, and a projector.

  In recent years, as the demand for miniaturization of projectors has increased, with the increase in output of semiconductor lasers and the appearance of blue semiconductor lasers, projectors or displays using laser light sources have been studied. Since the wavelength range of the light source is narrow, the color reproduction range can be greatly widened, and the size can be reduced and the number of components can be reduced. Yes.

As a light source of the display element, laser light sources of three colors of R (red), G (green), and B (blue) are necessary. For R and B, the source oscillation is present in the semiconductor laser, but for G, there is no source oscillation, and the second harmonic (SHG) generated by making the infrared laser incident on the nonlinear optical element is used. (For example, refer to Patent Document 1).
JP 2001-148536 A

  In the simplest display device, these lasers are two-dimensionally scanned to modulate the intensity of each beam to form an image. For example, in order to produce an image equivalent to HDTV, a beam modulation speed of at least GHz order is necessary, which is sufficiently possible with a semiconductor laser.

  In order to generate infrared laser light before wavelength conversion, there are parallel plate type lasers, VCSELs (surface emitting lasers having a resonator inside the element), and VECSELs (surface emitting lasers having a resonance mirror outside). VECSEL is often used from the viewpoint of beam quality and beam output. In the configuration in which VECSEL and SHG disclosed in Patent Document 1 are combined, a wavelength conversion element is placed inside the resonator in order to increase conversion efficiency. However, according to such a configuration, the wavelength conversion element needs to have a certain size, so that the resonator length becomes large, and the modulation speed of the converted light becomes slow (about several hundred kHz). .

  The present invention has been made to solve the above problems, and aims to realize high-speed modulation with respect to a light source device combining a surface emitting laser (VECSEL) having an external resonant mirror and a wavelength conversion element (SHG). Yes.

  In order to solve the above problems, a light source device of the present invention includes a surface emitting laser including a light emitting unit, an external resonant mirror that resonates light emitted from the light emitting unit, and light transmitted through the external resonant mirror. And a wavelength conversion element that converts the wavelength of the light.

  According to such a light source device, since the wavelength of light emitted from the surface emitting laser can be converted by the wavelength conversion element, desired color light can be obtained regardless of the type of the surface emitting laser. It becomes like this. In addition, since the wavelength conversion element is disposed outside the resonant mirror when viewed from the light emitting unit, the wavelength conversion element is disposed between the light emitting unit and the resonant mirror as in the conventional VECSEL. Thus, the resonance length can be reduced at least by the length of the wavelength conversion element, and the modulation speed can be increased.

  In the light source device of the present invention, the light source unit including the surface emitting laser, the resonant mirror, and the wavelength conversion element may be arranged in an array. The array of the light source unit can reduce the modulation speed required for one surface emitting laser, but the light source device of the present invention can be easily arrayed as compared with the conventional configuration. That is, for example, a method is adopted in which arrayed resonant mirrors are made, the distance between the two is controlled via a gap material in the arrayed light emitting section, and then the wavelength conversion elements are arrayed individually. be able to. Conventionally, since it is necessary to align the resonant mirror while maintaining the alignment of the wavelength conversion element, it has been difficult to manufacture. However, the present invention can omit such labor.

  In the light source device of the present invention, the wavelength conversion element is composed of a single structure, and the light source unit composed of the surface emitting laser and the resonant mirror is arranged in an array, and the single structure is Light from a plurality of light source units arranged in the array may be incident in common. In this case, the alignment of the wavelength conversion element is further simplified, and the manufacturing efficiency is further improved.

  Next, in order to solve the above-described problem, the scanning display device of the present invention scans the combined light with a red light source, a green light source, a blue light source, a light combining unit that combines light from each color light source. And at least one light source of the light source comprises the light source device. With such a scanning display device, it is possible to realize full color display with high image quality and high quality.

  Further, the scanning display device of the present invention includes, as different aspects, a red semiconductor laser light source, a blue semiconductor laser light source, a green light source composed of the light source device, a light combining unit that combines light from each light source, and a combining A scanning unit that scans the emitted light and displays an image. Also in this case, it is possible to realize a high-quality, high-quality full color display.

  Next, in order to solve the above problems, a projector according to the present invention projects the light source device, a light modulation device that modulates light emitted from the light source device, and light modulated by the light modulation device. And a projection device. With such a projector, it is possible to realize a high-quality and high-quality display.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, in order to make each layer and each member the size which can be recognized on drawing, the scale is varied for every layer and each member.

[First Embodiment]
FIG. 1 is a cross-sectional view schematically showing a light source device 50 according to a first embodiment to which the present invention is applied. The light source device 50 includes a light emitting unit 20 and an external resonant mirror 7. It is comprised using. The light emitting unit 20 that is the main light emitting element of the light source device 50 is a light emitting element that emits infrared laser light. As shown in FIG. 1, the first electrode 1, the semiconductor substrate 2, and the n- DBR mirror 3 are used. An active layer 4, a p-DBR mirror 9, a contact layer 5, and a second electrode 6. The semiconductor substrate 2 is a GaAs substrate here.

  The first electrode 1 is formed on the back surface side (a side different from the light emitting side) of the semiconductor substrate 2 and injects current into the active layer 4 in a pair with the second electrode 6. As the first electrode 1, for example, an electrode made of a laminated film of an alloy of Au and Ge and Au can be adopted.

  The n-DBR mirror 3 constitutes a resonator with the external resonant mirror 7 arranged outside the surface emitting laser 10. As this n-DBR mirror 3, for example, a mirror composed of 40 pairs of distributed reflection type multilayer mirrors in which n-type Al0.9Ga0.1As layers and n-type Al0.15Ga0.85As layers are alternately laminated may be adopted. it can.

  The active layer 4 includes a GaAs well layer and an Al0.3Ga0.7As barrier layer, and includes a quantum well structure in which the well layer is composed of three layers. In the active layer 4, when a forward voltage is applied to the Pin diode at the first electrode 1 and the second electrode 6, recombination of electrons and holes occurs, and light emission due to such recombination occurs.

  As the p-DBR mirror 9, for example, a p-type Al0.9Ga0.1As layer and a p-type Al0.15Ga0.85As layer can be adopted that is composed of five pairs of distributed reflection type multilayer mirrors.

  Here, the p-DBR mirror 9 is made p-type by doping C, for example, and the n-DBR mirror 3 is made n-type by doping Si, for example. Therefore, a pin diode is formed by the p-DBR mirror 9, the active layer 4 not doped with impurities, and the n-DBR mirror 3. The contact layer 5 can be formed by a p-GaAs layer, for example.

  The second electrode 6 is made of, for example, a laminated film of an alloy of Au and Zn and Au, has a predetermined opening pattern, and the opening 6a constitutes a light transmission portion.

  On the other hand, an external resonant mirror 7 is disposed outside the light emitting unit 20 (on the light emitting surface side). The external resonance mirror 7 may be any reflective film that can resonate with the p-DBR mirror 9 regardless of electrical characteristics. For example, a metal mirror having a low transmittance can be employed.

  Further, the wavelength conversion element 8 is disposed on the outside (light emission surface side) of the external resonant mirror 7 when viewed from the light emitting unit 20. The wavelength conversion element 8 is an element that converts the wavelength of the laser light emitted from the light emitting unit 20 and transmitted through the external resonant mirror 7, that is, the wavelength of the infrared laser light is converted to about half, and the green laser light is converted. Is creating.

  Here, an operation mode of the light source device 50 will be described. The following driving method of the light source device 50 is an example, and various modifications can be made without departing from the gist of the present invention. First, when a forward voltage is applied to the pin diode between the first electrode 1 and the second electrode 6, recombination of electrons and holes occurs in the active layer 4, and light emission due to such recombination occurs.

  The light generated in the active layer 4 undergoes stimulated emission when reciprocating between the n-DBR mirror 9 and the external resonant mirror 7, and the intensity of the light is amplified. When the optical gain exceeds the optical loss, laser oscillation occurs, and infrared laser light is emitted from the external resonant mirror 7 toward the wavelength conversion element 8.

  The emitted infrared laser light is transmitted (one pass) through the wavelength conversion element 8 so that its wavelength is converted. Here, the wavelength of the infrared laser light is reduced to be converted into green laser light, and is irradiated onto a predetermined irradiation object as light from the light source device 50.

  Since the light source device 50 as described above can convert the wavelength of the laser light emitted from the surface emitting laser 10 by the wavelength conversion element 8, it can acquire desired color light. . Further, since the wavelength conversion element 8 is disposed outside the external resonant mirror 7 when viewed from the light emitting unit 20, a wavelength conversion element is disposed between the light emitting unit and the resonant mirror as in the conventional VECSEL. Compared to the case, the resonance length can be reduced by at least the length of the wavelength conversion element, and the modulation speed can be increased.

[Second Embodiment]
Next, different embodiments of the light source device of the present invention will be described.
FIG. 2 is a schematic cross-sectional view showing the configuration of the light source device 51 according to the second embodiment, in which the surface emitting lasers 10 shown in FIG. 1 are arrayed on a substrate 11.

  Specifically, the light emitting units 20 are arranged in an array on the first substrate 11, while the external resonant mirror 7 is arranged in an array on the second substrate 12. At least the substrate 12 is made of a translucent material. The distance between the substrates of the first substrate 11 and the second substrate 12 is controlled via a gap material, and alignment in the plane direction is also performed. The wavelength conversion elements 8 are arranged in an array on the substrate 12 in a one-to-one correspondence with the individual surface emitting lasers 10.

  According to such a light source device 51, for example, the external resonant mirror 7 arrayed on the substrate 12 is made, and the distance between the two is set via the gap material to the light emitting unit 20 arrayed on the substrate 11. After the control, a method of individually aligning the wavelength conversion elements 8 can be employed. Conventionally, since it is necessary to align the external resonant mirror 7 while maintaining the alignment of the wavelength conversion element 8, it has been difficult to manufacture, but in the present embodiment, such labor can be omitted.

[Third Embodiment]
Next, different embodiments of the light source device of the present invention will be described.
FIG. 3 is a schematic cross-sectional view showing the configuration of the light source device 52 according to the third embodiment, in which the surface emitting lasers 10 shown in FIG. 1 are arranged on the substrate 11 in an array.

  Specifically, the light emitting units 20 are arranged in an array on the first substrate 11, while the external resonant mirror 7 is arranged in an array on the second substrate 12. At least the substrate 12 is made of a translucent material. The distance between the substrates of the first substrate 11 and the second substrate 12 is controlled via a gap material, and alignment in the plane direction is also performed. A bulk wavelength conversion element 80 is disposed on the substrate 12. That is, the wavelength conversion element 80 has a configuration common to the individual surface emitting lasers 10 and is not patterned.

  According to such a light source device 52, the wavelength conversion element 80 is formed of a single structure, while the light emitting unit and the external resonance mirror 7 are arranged in an array. On the other hand, each light from the plurality of surface emitting lasers 10 arranged in an array is incident in common. In this case, the alignment of the wavelength conversion element 80 is further simplified, and the manufacturing efficiency is further improved.

[Fourth Embodiment]
Next, an embodiment of a display device using the light source device 50 will be described.
FIG. 4 is a block diagram showing a schematic configuration of the full-color scanning display device 100. The scanning display device 100 includes a light source including a red light source 102, a green light source 110, and a blue light source 103, a reflection plate 103 that reflects red light, a reflection plate 104 that reflects blue light, and transmits green light. A dichroic mirror 105 that reflects red light; a dichroic mirror 106 that transmits green light and reflects blue light; a scanning mirror 107 that scans light from a light source; and a display board 108 that displays light from the scanning mirror 107 as an image. It has.
The green light source 110 is composed of the light source device 50 shown in FIG.

  The red light emitted from the red light source 102 is reflected by the reflecting plate 103 and the dichroic mirror 105, further passes through the dichroic mirror 106, and is guided to the scanning mirror 107. The blue light emitted from the blue light source 101 is reflected by the reflecting plate 104 and the dichroic mirror 106 and guided to the scanning mirror 107. Further, the green light emitted from the green light source 110 passes through the dichroic mirror 105 and the dichroic mirror 106 and is guided to the scanning mirror 107. The scanning mirror 107 performs scanning according to the image projected on the display board 108.

[Fifth Embodiment]
Next, an embodiment of a projector using the light source device 50 will be described.
FIG. 5 is a diagram showing a schematic configuration of the projector 70, which is an example of a three-plate system. The projector 70 includes an array light source 10r in which semiconductor lasers that emit red (R) color light are two-dimensionally arranged in an array, and an array that emits green (G) color light that includes the light source device 50 shown in FIG. Three light sources 10g and array light sources 10b in which semiconductor lasers emitting blue (B) color light are two-dimensionally arranged in an array are used as light sources.

  The light emitted from each of the array light sources 10r, 10g, and 10b is applied to the liquid crystal light valve 75. That is, a liquid crystal light valve 75 that modulates each color light of R, G, and B is provided on the emission side of each of the array light sources 10r, 10g, and 10b. Then, the three color lights modulated by the respective liquid crystal light valves 75 are configured to enter a cross dichroic prism (color combining means) 77. The prism 77 is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. These dielectric multilayer films combine the three color lights Lr, Lg, and Lb to form light representing a color image. The color-synthesized light is projected onto the screen 79 by the projection lens 76 (projection device), and an enlarged image is displayed.

The cross-sectional schematic diagram which shows schematic structure about 1st Embodiment of the light source device of this invention. The cross-sectional schematic diagram which shows schematic structure about 2nd Embodiment of the light source device of this invention. The cross-sectional schematic diagram which shows schematic structure about 3rd Embodiment of the light source device of this invention. 1 is a block diagram illustrating an example of a scanning display device. The block diagram which shows an example of a projector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 7 ... External resonance mirror (resonance mirror), 8 ... Wavelength conversion element, 10 ... Surface emitting laser, 20 ... Light emission part, 50 ... Light source device

Claims (6)

  A surface-emitting laser including a light emitting unit, an external resonant mirror that resonates light emitted from the light emitting unit, and a wavelength conversion element that converts the wavelength of the light transmitted through the external resonant mirror. A light source device characterized by the above.   The light source device according to claim 1, wherein a light source unit including the surface emitting laser and the wavelength conversion element is arranged in an array.   While the wavelength conversion element is formed of a single structure, the surface emitting lasers are arranged in an array, and light from a plurality of surface emitting lasers arranged in the array on the single structure is received. The light source device according to claim 1, wherein the light source devices are commonly incident.   A scanning display device comprising: a red light source, a green light source, a blue light source, a light combining unit that combines light from each color light source, and a scanning unit that scans the combined light and displays an image. A scanning display device, wherein the light source of at least one color of the light source comprises the light source device according to any one of claims 1 to 3.   A red semiconductor laser light source, a blue semiconductor laser light source, a green light source comprising the light source device according to any one of claims 1 to 3, a light combining unit for combining light from each light source, and a combined light And a scanning unit that scans and displays an image.   A light source device according to any one of claims 1 to 3, a light modulation device that modulates light emitted from the light source device, and a projection device that projects light modulated by the light modulation device. A projector characterized by that.

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