JP2009230055A - Diffraction grating device and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact diffraction grating device capable of performing optical alignment in design level of a semiconductive element, and to provide a display device. <P>SOLUTION: The diffraction grating device comprises: a semiconductor substrate 20 provided with a hollow section 22 on a surface; a wave guide passage 25 formed on the semiconductor substrate for propagating the light from a light source; a focus grating coupler 30 having a diffraction grating formed on the hollow section and variable in grating period for diffracting the light propagated from the wave guide passage, and changing the direction of diffraction light by changing the grating period; and a supporting section 40 connected with the semiconductor substrate at its one end and supporting the focus grating coupler. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a diffraction grating device and a display device, and more particularly to a diffraction grating device having a variable pitch and a display device using the diffraction grating device.

  In recent years, highly functional devices such as electronic devices, sensors, and actuators using MEMS (Micro Electro Mechanical Systems) technology have been rapidly developed. As an application of the MEMS technology to an optical apparatus such as a display device or a scanner, there is a technology of modulating incident light for each pixel by a MEMS device. In this case, the MEMS device serves as a switching device that performs ON / OFF control on the light wave.

  As a mechanism for modulating a light wave, a mirror type represented by a digital micro mirror device (hereinafter also referred to as DMD (Digital Micro Mirror Device)) and a diffraction grating light valve (hereinafter referred to as GLV (Grating Light Valve)). 2) of diffraction grating types represented by

  DMD, for example, allows a reflecting mirror having a size of about 15 μm to 25 μm to be tilted about 10 degrees back and forth, and makes the reflection direction of the optical axis variable. However, since DMD requires a mechanism to tilt the reflector, the structure of the hinge part that supports the mirror surface is complicated and the manufacturing cost is high, and problems to be solved in terms of manufacturing yield, durability, high-speed response, etc. There are also many.

  As GLV, one having a structure in which ribbon-like diffraction elements are arranged in a line on a silicon substrate is disclosed (Non-patent Document 1). These diffractive elements are alternately provided with fixed diffractive elements and diffractive elements that can be bent downward by being drawn in by an electrostatic force. When no bias is applied, all the diffractive elements are on the same plane and no diffracted light is generated. On the other hand, when a bias is applied, the movable diffractive element is bent downward, and an uneven surface is formed with the fixed diffractive element. Light is diffracted by the uneven surface to generate diffracted light.

  On the other hand, in order to increase the degree of optical freedom, a structure has been proposed in which it is not necessary to install a driving electrode below the diffraction grating by driving the diffraction grating in the horizontal direction of the substrate (Non-Patent Document 2). .

A MEMS device using such a diffraction grating is advantageous in that a large optical modulation is applied with a small mechanical displacement and a high-speed response is possible. Also, mechanical reliability is high. For this reason, they are applied to display devices, printer scanners, gain equalizers for optical communication, and the like.
D. Bloom, "The Grating Light Valve: Revolutionizing Display Technology," Projection Displays III Symposium, SPIE Proceedings Volume 3013, February 1997 K. Takahashi, H. Fujita, H. Toshiyoshi, K. Suzuki, H. Funaki, K. Itaya, "Tunable light grating integrated with high-voltage driver IC for image projection display," Proc. IEEE Micro Electro Mechanical Systems, pp 147-150, 2007, Kobe, Japan

  However, in a conventional display device using DMD, GLV, diffraction grating, or any one of them, it is necessary to arrange a light source at a spatially separated position with respect to an element that mechanically switches light waves. . For this reason, there has been a problem that the size of the occupied system is increased with respect to a liquid crystal display device or the like having a backlight on the back side.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a diffraction grating device and a display device that are small in size and capable of optical alignment at the design level of a semiconductor element.

  A diffraction grating device according to a first aspect of the present invention includes a semiconductor substrate having a cavity portion formed on a surface thereof, a waveguide formed on the semiconductor substrate and propagating light from a light source, and formed on the cavity portion. And a focus grating coupler that changes the direction of the diffracted light by changing the grating period, and one end connected to the semiconductor substrate. And a support portion for supporting the focus grating coupler.

  Further, the display device according to the second aspect of the present invention projects the diffraction grating device according to the first aspect, a drive unit that drives each of the focus grating couplers, and diffracted light from each of the focus grating couplers. And a projection unit.

  According to the present invention, it is possible to provide a diffraction grating device and a display device that are small in size and capable of optical alignment at the design level of a semiconductor element.

(First embodiment)
The diffraction grating device according to the first embodiment of the present invention is shown in FIG. The diffraction grating device 1 of the present embodiment is disposed above the light source 10, the semiconductor substrate 20 provided with a cavity (concave portion) 22 on the surface, the waveguide 25 formed in the semiconductor substrate 20, and the concave portion 22. A focus grating coupler (hereinafter also referred to as FGC (Focusing Grating Coupler)) 30, a support portion 40 that supports the FGC 30 in a state of being floated above the recess 22, and a wiring 50 provided on the semiconductor substrate 20. ing.

  The waveguide 25 is connected to the light source 10 and transmits a light wave from the light source 10 to the FGC 30. The waveguide 25 and the FGC 30 are optically connected. The FGC 30 includes a diffraction grating (grating) 32, a movable electrode 34, and a fixed electrode 36. By applying a voltage to the fixed electrode 36 from the outside through the wiring 50, an electrostatic force acts between the fixed electrode 36 and the movable electrode 34 of the FGC 30, and the spatial period (interval) of the diffraction grating 32 changes. That is, in this embodiment, the interval (period) of the diffraction grating 32 can be electrically varied by the movable electrode 34 and the fixed electrode 36. When the spatial period (interval) of the grating 32 satisfies a certain condition, coupling between the guided mode and the radiation mode occurs. Such a grating is called an FGC because it is used as an input / output coupler for exciting guided light and taking it out from the outside.

で表される。Δε_ｑはグレーティング３２を取り付けたことによる比誘電率分布の変化を表している。グレーティング３２がある場合、この構造内をｚ方向に伝搬定数β_０＝Ｎｋ（＞０）をもつ導波光が伝搬するとき、この波に付随してｚ方向伝搬定数

をもつ空間高調波が生じる。ここで、Ｎは導波層中を伝搬するモードの等価屈折率、Ｋは格子ベクトルとよばれるグレーティング面に垂直なベクトルで、Λはグレーティングの基本周期である。基板、導波層、上部クラッド層の屈折率を各々、ｎ_ｓ、ｎ_ｆ、ｎ_ｃとし、空間高調波のうち｜β_ｑ｜＝ｎ_ｃｋまたは｜β_ｑ｜＝ｎ_ｓｋを満たす次数ｑが存在する場合は、この高調波の空気側または基板側にそれぞれ、

で決まる伝搬角θ^(c) _q、θ^(s) _qの放射となる。このときＦＧＣを伝搬する波は放射により導波路外部に漏洩する。グレーティングはｚ方向には長いがｘ方向には薄いので、結合する波動間はｚ方向の位相整合（３）式のみが満たされればよく、伝搬ベクトルダイアグラムは図２（ｂ）に示すようになる。この結合で生じる放射ビームは（３）式を成立させる伝搬角θ^(c) _q、θ^(s) _qの実数値で決まる。（３）式において、ｎ_ｃ＜ｎ_ｓ＜Ｎ＜ｎ_ｆであることを考慮すれば、放射はｑ≦−１の次数に限られ、ある次数のみは基板側のみに放射する場合と、基板側と空気側の両方に放射する場合があることがわかる。図２（ａ）、（ｂ）は複数の次数で３本以上のビームが生じる例で多ビーム結合とよばれる。基本次数（ｑ＝−１）の放射が生じる場合について、Ｋ／ｋ、Ｎと式（３）で決まる放射ビーム数は図３で表される。ＦＧＣに導波光が入射した場合、上述のような出力結合が生じる。このグレーティングのパターンを変調することにより種々の波面変換を導波モード−放射モード結合と同時に実行することも可能になる。これを応用して、導波光を自由空間の点に集光するＦＧＣを実現することができる。 Hereinafter, the concept of FGC used in the present embodiment and focused in free space will be described. The following explanation is quoted from “Optical Integrated Circuit, Hiroshi Nishihara, Masamitsu Haruna, Toshiaki Sugawara, Ohmsha (1985)”. 2A and 2B show examples of guided mode-radiation mode coupling when guided light is incident on the FGC. It spreads along the waveguide surface (xz plane) of the two-dimensional waveguide optical path,

It is represented by Δε _q represents a change in relative permittivity distribution due to the attachment of the grating 32. When there is a grating 32, when guided light having a propagation constant β ₀ = Nk (> 0) propagates in this structure in the z direction, the z direction propagation constant accompanies this wave.

Spatial harmonics with Here, N is an equivalent refractive index of a mode propagating in the waveguide layer, K is a vector perpendicular to the grating plane called a grating vector, and Λ is a fundamental period of the grating. Each substrate, waveguide layer, the refractive index of the upper cladding _layer, and _{n s, n f, n c} , of which the spatial harmonics | β _q | = _{n c} k or | beta _q | meet = _{n s} k orders If q is present, the air side or the substrate side of this harmonic,

The radiation of the propagation angles θ ^(c) _q and θ ^(s) _q determined by At this time, the wave propagating through the FGC leaks outside the waveguide due to radiation. Since the grating is long in the z direction but thin in the x direction, it is only necessary to satisfy the phase matching (3) equation in the z direction between the coupled waves, and the propagation vector diagram is as shown in FIG. . The radiation beam generated by this coupling is determined by the real values of the propagation angles θ ^(c) _q and θ ^(s) _q that establish equation (3). In the formula (3), considering that n _c <n _s <N <n _f , radiation is limited to the order of q ≦ −1, and only a certain order is emitted only to the substrate side, It can be seen that radiation may occur on both the air and air sides. 2A and 2B are examples in which three or more beams are generated in a plurality of orders, and are called multi-beam coupling. In the case where radiation of the basic order (q = −1) occurs, the number of radiation beams determined by K / k, N and Equation (3) is expressed in FIG. When guided light enters the FGC, output coupling as described above occurs. By modulating the grating pattern, various wavefront transformations can be performed simultaneously with the waveguide mode-radiation mode coupling. By applying this, it is possible to realize an FGC that condenses guided light at a point in free space.

  Next, in the diffraction grating device of this embodiment, a configuration in which the light source 10 and the semiconductor substrate 20 provided with the optical waveguide 25 are optically coupled is schematically shown in FIG. Here, the light source 10 is exemplified by a general stripe type semiconductor laser chip. The stripe type semiconductor laser chip 10 covers both sides of an active layer 10b exhibiting photorefractive characteristics with cladding layers 10a and 10c having a lower refractive index than the active layer 10b. When a red semiconductor laser is considered, a material such as AlGaAs can be used for the active layer. Optical coupling between the semiconductor laser 10 and the semiconductor substrate 20 having the optical waveguide 25 is coupled at each end face. The optical waveguide itself is also covered with a low refractive material layer (not shown) on both sides of the waveguide layer (not shown), and the waveguide layer has a high refractive index distribution. A light wave can be propagated by coupling the active layer 10b of the light source 10 and the waveguide 25 so as not to cause axial misalignment. In order to avoid attenuation of light wave energy at the interface, an optical thin film such as an AR coat may be applied.

  1 and 4, the semiconductor laser chip 10 is described as being disposed at a different position from the semiconductor substrate 20. However, as shown in FIG. 5A, the semiconductor substrate 20 is provided with a recess 20 a in advance. The semiconductor laser chip 10 may be incorporated in the recess 20a. Further, as shown in FIG. 5B, the light source can be disposed on the surface of the semiconductor substrate 20 by using a surface emitting semiconductor laser 10 </ b> A as the light source. In this case, a vertical waveguide is provided with respect to the waveguide layer of the optical waveguide 25 in order to prevent attenuation of light energy in a region bonded to the semiconductor substrate 20 below the light emitting layer of the surface emitting semiconductor laser 10A. There is a need. If the surface emitting laser 10A is used as a light source, it is possible to irradiate light waves in an array, and there is an advantage that more light rays can be handled in a low volume. By adopting such a configuration, it becomes possible to install a light source that has been conventionally positioned in the height direction (z-axis direction) of the three-dimensional space in the same plane as the substrate, and space saving can be achieved. Can do. The light source 10 may be optically connected to the semiconductor substrate 20 through a photocoupler.

  Next, the electrostatic drive system of the FGC 30 will be described with reference to FIG. A movable electrode 34 for driving is provided on the FGC 30 which is separated from the surroundings and connected by the support portion 40. The movable electrode 34 has a comb shape. On the other hand, a comb-shaped fixed electrode 36 is provided on the substrate 20 so as to face the comb-shaped movable electrode 34 provided on the FGC 30. Electrically separated electric wirings 50a and 50b are drawn out from the electrodes 36 and 34, respectively. Here, by applying the power supply voltage 60 between the electrodes 36 and 34 via the electric wirings 50a and 50b, the FGC 30 is attracted to the fixed electrode 36 side by electrostatic force. Since the FGC 30 is supported by the support portion 40 serving as a spring, the grating period of the diffraction grating 32 provided in the FGC 30 is changed by being attracted as described above. As the lattice period Λ shown in the equation (1) changes, the spatial propagation constant also changes, and the vector in the normal direction also changes. That is, the direction of the diffracted light propagating in space can be shifted by changing the period to an arbitrary grating period by electrostatic attraction. As described above, according to the present embodiment, the directivity of the diffracted light is switched to an arbitrary period or angle between the FGC in the initial state where no electrostatic force is generated and the FGC whose lattice period is changed by the electrostatic attractive force. It becomes possible to do.

  FIG. 7 shows a diffraction grating device in which the grating period variable FGC 30 shown in FIG. 6 is two-dimensionally arranged. The operation mechanism of this device is as described above, and it can function as a display device by making an array. Each FGC 30 is controlled by the control circuit 70, and the diffraction angle of the diffracted light can be varied by electrostatically driving the FGC 30 at an arbitrary position by the control circuit 70 at an arbitrary timing. For example, it is possible to display the VGA class by setting the number of FGC 30 arrays to 640 × 480 elements, arranging them uniformly, and switching them. That is, by changing the grating period, the light wave 100 extracted in the direction to be displayed is switched to ON light, and the discarded light wave is switched to OFF light. Here, as the ON light / OFF light, either the light before changing the lattice period electrostatically or the light having changed may be used.

  FIGS. 8A and 8B are diagrams showing the operation of a specific example of the FGC 30. FIG. According to FIG. 8A, the FGC 30 is connected to the substrate by four anchors 90 supported by springs (not shown). In addition, a waveguide for introducing a light wave is connected to one end of the FGC 30. The diffraction gratings 32 constituting the FGC 30 are connected to each other by thin springs 92. On the other hand, the other end of the FGC 30 is provided with a comb-like movable electrode 34 and is disposed opposite to a fixed comb-like fixed electrode 36 formed on the substrate. By applying a bias voltage between the comb-shaped movable electrode 34 and the comb-shaped fixed electrode 36, the comb-shaped movable electrode 34 is attracted toward the comb-shaped fixed electrode 36 by electrostatic force. . Here, since the diffraction gratings 32 are connected to each other by a thin spring, the entire grating expands and contracts like a bellows (FIG. 8B). The fluctuation of the period of the diffraction grating 32 can be controlled by the amount of voltage to be applied. As shown in FIGS. 2 and 3, by changing the grating period, the radiation angle of the diffracted light can be made variable.

Next, a method for manufacturing the diffraction grating device according to the present embodiment is shown in FIGS. When a silicon substrate is used as the semiconductor substrate 20 on which the optical waveguide 25 is formed (FIG. 9A), the refractive index is relatively high (n _s = 3.42 (for light with a wavelength of λ = 1 μm)). Therefore, it is desirable to form the buffer layer 25a before forming the waveguide layer of the optical waveguide 25. An example of a material suitable for the buffer layer 25a is SiO ₂ (n _b = about 1.5). A buffer layer 25a is formed on a semiconductor substrate 20 such as silicon by sputtering or CVD (FIG. 9B). Subsequently, a waveguide layer 25b is formed on the buffer layer 25a (FIG. 9B). A material having a slightly higher refractive index than that of the buffer layer 25a is used for the waveguide layer 25b. For example, since Si ₃ N ₄ has a refractive index n _f of about 2, it is a useful material in the above-described configuration. Similarly, the waveguide layer 25b made of Si ₃ N ₄ is formed by sputtering or CVD. In addition to Si ₃ N ₄ , organic materials such as PMMA, polymers, and photoresists may be used. Here, it is necessary to make these buffer layer 25a and waveguide layer 25b into a desired shape.

  Next, the FGC 30 is formed on a part of the waveguide layer 25b (FIG. 9C). The FGC 30 is formed of a patterned photoresist, or is formed by partially etching the waveguide layer material using this photoresist as a mask. Subsequently, as shown in FIG. 9D, an opening 26 is formed in the waveguide layer 25b buffer layer 25a so as to separate the region where the FGC 30 is formed from other regions, and a semiconductor substrate is formed at the bottom of the opening 26. Twenty surfaces are exposed. Thereafter, the cavity 22 is provided in the semiconductor substrate 20 by wet etching or the like (FIG. 9E). In the figure, the cavitation process is anisotropically performed, but the process is not particularly limited, and may be performed isotropically by a dry process. Thus, after producing the optical waveguide, it is coupled with the semiconductor laser chip 10 to complete the diffraction grating device 1.

  As described above, when a highly refractive material such as silicon is used for the substrate, it is desired to form a buffer layer. However, an SOI substrate can be used as a substrate, and a buried oxide film (hereinafter also referred to as BOX) can be used as a buffer layer. A configuration example of an optical waveguide formed using an SOI substrate as a semiconductor substrate is shown in FIG. A groove is formed in the SOI layer 21c of the SOI substrate 21 having the support substrate 21a, the buried oxide film 21b, and the SOI layer 21c, and the groove is buried with a waveguide layer material, thereby forming the waveguide layer 25b. A manufacturing method using an SOI substrate is shown in FIGS. 11 (a), FIG. 11 (c), FIG. 12 (a), and FIG. 12 (c) are cross-sectional views taken along the cutting line AA ′ shown in FIG. 10, and FIG. 11 (b) and FIG. 11 (d), FIG. 12 (b), and FIG. 12 (d) are cross-sectional views taken along the cutting line BB ′ shown in FIG.

  First, an SOI substrate 21 having a support substrate 21a, a buried oxide film 21a, and an SOI layer 21c is prepared. Subsequently, an opening 23 serving as a waveguide region is formed in the SOI layer 21c by a lithography technique (FIGS. 11A and 11B). A buried oxide film 21 b is exposed at the bottom of the opening 23. That is, the buried oxide film 21b is used as an etch stop layer. Subsequently, a film 24 made of, for example, SiN having a refractive index higher than that of the buried oxide film is buried in the opening 23 by using a CVD method or the like (FIGS. 11C and 11D). Thereafter, an FGC 30 is formed on a part of the SiN film 24 by slightly etching a patterned photoresist resist or waveguide layer material. Next, the groove | channel 26 which isolate | separates the area | region in which FGC30 was formed from another area | region is formed (FIG. 12 (a), (b)). At the bottom of the groove 26, the upper surface of the support substrate 21a is exposed. Thereafter, the cavity 22 is provided in the support substrate 21a using wet etching or the like (FIGS. 12C and 12D).

  Even when an SOI substrate is used, an FGC and a diffraction grating device having a structure in which the FGC is separated from the substrate can be formed by forming a buffer layer and a waveguide layer on the SOI layer. This will be described with reference to FIGS. 13 (a) to 14 (d). 13 (a), 13 (c), 14 (a), and 14 (c) are cross-sectional views in the first direction (for example, a cross-sectional view cut along the cutting line AA ′ shown in FIG. 10). 13 (b), 13 (d), 14 (b), and 14 (d) are cross-sectional views in the second direction orthogonal to the first direction (for example, the cutting line B shown in FIG. 10). It is sectional drawing cut | disconnected by -B '.

  First, an SOI substrate 21 having a support substrate 21a, a buried oxide film 21a, and an SOI layer 21c is prepared (FIGS. 13A and 13B). Subsequently, a buffer layer 25a and a waveguide layer 25b are formed on the SOI layer 21c. Thereafter, the FGC 30 is formed on the waveguide layer 25b (FIGS. 13C and 13D). Next, the groove | channel 26 which isolate | separates the area | region in which FGC30 was formed from another area | region is formed (FIG. 14 (a), (b)). At the bottom of the groove 26, the upper surface of the support substrate 21a is exposed. Thereafter, the cavity 22 is provided in the support substrate 21a by using wet etching or the like (FIGS. 14C and 14D).

  As described above, according to the present embodiment, it is possible to provide a diffraction grating device that is compact and capable of optical alignment at the design level of the semiconductor element.

(Second Embodiment)
Next, a display device according to a second embodiment of the present invention is shown in FIG. As shown in FIG. 7, the display device of the present embodiment is diffracted by the FGC 30 and the diffraction grating device 1 having the grating cycle variable FGC 30 of the first embodiment arranged two-dimensionally on the semiconductor substrate 20. And a projection unit 150 such as a screen provided at the radiation destination of the light wave 160. In FIG. 15, the light source is not shown, but is included in the diffraction grating device 1. By setting it as such a structure, the light wave radiated | emitted from the board | substrate 20 can be visualized. The projected light spot 170 is two-dimensionalized, and each forms a pixel as a display device. Here, for the light wave (display pixel) 170 to be projected onto the screen 150, the radiation angle of the light beam is directed to the screen 150. On the other hand, non-displayed pixels are excluded by emitting to an angle outside the screen. As described above, switching of the diffracted light is performed by changing the grating period of the FGC 30 so as to correspond to the display / non-display pixels on the screen 150. The numerical value of the FGC 30 array formed on the substrate 20 is defined by the resolution of the image to be displayed. In the above, the same number of FGC arrays corresponding to pixels forming a two-dimensional image are prepared two-dimensionally.

  On the other hand, line scanning may be applied to make a one-dimensional light beam two-dimensional. FIG. 14 is a schematic diagram illustrating this. Radiated light from the FGC 30 arranged one-dimensionally on the substrate is projected onto the galvanometer mirror 140. As shown in the drawing, the light beam from the FGC 30 arranged one-dimensionally is projected on the galvano mirror 140 in the one-dimensional direction in the height direction. The diffracted light reflected from the galvanometer mirror 140 is projected onto the screen 150. Here, the diffracted light is scanned two-dimensionally on the screen 150 by horizontally scanning the galvanometer mirror 140. The driving frequency of the galvanometer mirror 140 is 60 Hz, for example. The display / non-display method of each pixel on the screen 150 is the same as that of the display device according to the second embodiment described with reference to FIG. As described above, in the light modulation element substrate in which the FGC 30 is arranged one-dimensionally or two-dimensionally, the light wave radiated from the FGC 30 can be projected on the screen to act as a display device.

  As described above, according to the present embodiment, it is possible to provide a display device that is compact and capable of optical alignment at the design level of the semiconductor element.

  Such a diffraction grating device and a display device can greatly reduce the space occupied in the two-dimensional or three-dimensional spatial direction, and can reduce the size of the system.

As a light source of light waves to be introduced into the FGC, a laser diode (LD) using a compound semiconductor or a vertical cavity surface emitting semiconductor laser (VCSEL) is used, and R (red), G (green), and B (blue). Color display is possible by using a light source having specific emission characteristics.

  On the other hand, by emitting light from silicon nanocrystals or laminating a luminescent compound on a silicon substrate, a light source can be formed in a semiconductor substrate having FGC, and a more compact system can be provided.

The perspective view which shows the diffraction grating apparatus by 1st Embodiment of this invention. The figure explaining the concept of FGC. The figure which shows the relationship between K / k and N, and the number of radiation beams about the case where radiation of a basic order arises. The figure explaining the coupling | bonding of a light source and a semiconductor substrate. The perspective view which shows the example of the coupling | bonding of the semiconductor laser as a light source, and a semiconductor substrate. The perspective view explaining the drive method of the diffraction grating device by a 1st embodiment. The perspective view which shows the diffraction grating apparatus by the modification of 1st Embodiment with which FGC was arranged two-dimensionally. The figure explaining operation | movement of the diffraction grating apparatus by 1st Embodiment. Sectional drawing explaining the 1st manufacturing method of the diffraction grating apparatus by 1st Embodiment. The perspective view explaining the 2nd manufacturing method of the diffraction grating device by a 1st embodiment. Sectional drawing explaining the 2nd manufacturing method of the diffraction grating apparatus by 1st Embodiment. Sectional drawing explaining the 2nd manufacturing method of the diffraction grating apparatus by 1st Embodiment. Sectional drawing explaining the 3rd manufacturing method of the diffraction grating apparatus by 1st Embodiment. Sectional drawing explaining the 3rd manufacturing method of the diffraction grating apparatus by 1st Embodiment. The schematic diagram which shows the display apparatus by 2nd Embodiment of this invention. The schematic diagram which shows the display apparatus by the modification of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diffraction grating apparatus 10 Light source 10A Surface emitting semiconductor laser chip 10a Clad layer 10b Active layer 10c Clad layer 20 Semiconductor substrate 20a Recess 21 SOI substrate 21a Support substrate 21b Embedded oxide film 21c SOI layer 22 Cavity (recess)
24 Waveguide layer 25 Waveguide 25a Buffer layer 25b Waveguide layer 30 FGC
32 Diffraction grating 34 Movable electrode 36 Fixed electrode 40 Support part 50 Electric wiring 60 Power supply voltage 70 Control circuit 90 Anchor 92 Spring 140 Galvano mirror 150 Screen 160 Light wave 170 Projection light

Claims (8)

A semiconductor substrate having a cavity formed on the surface;
A waveguide formed on the semiconductor substrate and propagating light from a light source;
A focus grating coupler that is formed on the cavity and has a diffraction grating having a variable grating period for diffracting light propagating from the waveguide, and changing a direction of diffracted light by changing the grating period;
A support part having one end connected to the semiconductor substrate and supporting the focus grating coupler;
A diffraction grating device comprising:   The diffraction grating device according to claim 1, wherein the light source is optically connected to a waveguide of the semiconductor substrate.   The focus grating coupler includes a first electrode and a second electrode fixed to the semiconductor substrate, and the lattice period is changed by an electrostatic force generated between the first electrode and the second electrode. The diffraction grating device according to claim 1 or 2, wherein   The diffraction grating device according to claim 1, further comprising a control circuit mounted on the semiconductor substrate and configured to change a grating period of the diffraction grating.   5. The focus grating coupler is capable of emitting a light wave propagated from the waveguide at an arbitrary timing and an arbitrary angle by changing the grating period. The diffraction grating device according to any one of the above.   6. The diffraction grating device according to claim 1, wherein a plurality of the focus grating couplers are arranged one-dimensionally or two-dimensionally on the semiconductor substrate.   7. The diffraction grating device according to claim 6, comprising: a driving unit that drives each of the focus grating couplers; and a projection unit that projects diffracted light from each of the focus grating couplers. Display device.   The diffraction grating device further includes a galvanometer mirror in which a plurality of the focus grating couplers are arranged in a one-dimensional manner on the semiconductor substrate and reflects diffracted light from each of the focus grating couplers to the projection unit. The display device according to claim 7.

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