JP2005189385A - Branch type optical waveguide, light source module, and optical information processing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a branch type optical waveguide which takes in rays of light from a plurality of light sources which are arranged opposed to a plurality optical waveguides and which multiplexes them and emits them and which can emits the multiplexed light in which rays of light from the plurality of the light sources are included at prescribed ratios and whose minuaturization is also possible, a light source module using the branch type optical waveguide and an optial information processing unit, such as a display. <P>SOLUTION: In three branch type optical waveguide 10, after a plurality of rays of light 6 which are taken in at ratios of light intensities of respective light sources 5 are adjusted so that intensity and/or light quantities of the respective rays of light become to be prescribed ratios by attenuating them using optical loss when they propagate the core part 1 of the waveguide 10 and they are multiplexed. For example, when a core part 1B for blue light and a core part 1R for red light attenuate respectively the intensity of propagating rays of light to 50%, 33%, an outgoing light (multiplexed light) 7 which includes rays of light of three primary colors by intensity ratios of green light:blue light:red light=1:1:1 can be obtained from light sources of three primary colors whose ratios of optical outputs are green light:blue light:red light=1:2:3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a branched optical waveguide composed of a joined body of a core and a clad, and suitable for a light source module, optical interconnection, optical communication, etc., for combining a plurality of incident lights, and a light source using the branched optical waveguide The present invention relates to a module and an optical information processing apparatus such as a display and a projector.

  Until now, information transmission over a relatively short distance, such as between boards in electronic equipment or between chips in a board, has been performed mainly by electrical signals, but in order to further improve the performance of integrated circuits. Therefore, it is necessary to increase the signal speed and the signal wiring density. However, in the electric signal wiring, it is difficult to increase the speed of the electric signal and increase the density of the electric signal wiring due to problems such as signal delay due to the time constant of the wiring and generation of noise.

  Optical wiring (optical interconnection) that solves these problems is drawing attention. Optical wiring can be applied to various locations such as between electronic devices, between boards in electronic devices, or between chips in a board. For example, chips are mounted for transmission of signals over a short distance such as between chips. It is possible to construct an optical transmission / communication system in which an optical waveguide is formed on a substrate that is used as a transmission path for signal-modulated laser light or the like.

  In addition, an optical waveguide is applied to a light source module such as a display. For example, a head-mounted display has been developed as a personal display that can be easily experienced anytime and anywhere just by wearing it like sunglasses (see US Pat. No. 5,467,104). You can enjoy video software, games, computer screens, movies, etc. on your own big screen.

  Red (R), green (G), and blue (B) light emitting diodes (LEDs) are used as the light source of this head mounted display, and these LED lights are combined to make it look like a point light source. There is a strong demand for LED modules that can be used in the future.

  In Patent Document 1 and Patent Document 2, which will be described later, a plurality of waveguide core portions are formed by using one end portion forming a light incident end face and connecting the other end portion to one waveguide core portion. A method of optically combining light from the light sources is disclosed. It is expected that this method is applied to the multiplexing of light from the three-color LED light sources of red (R), green (G), and blue (B) to realize miniaturization of the full-color white light source module.

  FIG. 10 shows a light source module that combines the light from the red light source 65R, the green light source 65G, and the blue light source 65B using the so-called three-branch optical waveguide 60 to obtain a spot-like white light source based on the above method. FIG. In the three-branch type optical waveguide 60, one end portions of the red light core portion 61R, the green light core portion 61G, and the blue light core portion 61B are respectively connected to the red light incident end surface 63R, the green light incident end surface 63G, and the blue light. The light incident end face 63B is formed, and the other end is coupled to the end of the multiplexing core 61C. The other end portion of the multiplexing core portion 61C forms a light emitting end face 64.

  On the light incident end faces 63R, 63G, and 63B, a red light source 65R, a green light source 65G, and a blue light source 65B are provided to face each other. The red light 66R, green light 66G, and blue light 66B incident on the light incident end face 63 from each light source 65 travel through the red light core portion 61R, the green light core portion 61G, and the blue light core portion 61B, respectively. The light is guided to the multiplexing core portion 61 </ b> C and multiplexed, and emitted from the light emitting end face 64 as spot-like white light 67.

  At this time, the core 61 (core portions 61R, 61G, 61B, and 61C) is made to have a refractive index larger than that of the clad 62 covering the core 61. As shown by the arrows in FIG. 10, the light travels through the core 61 toward the light emitting end face 64 while being substantially totally reflected at the boundary surface between the core 61 and the clad 62.

Japanese Unexamined Patent Publication No. 63-228788 (2nd page, FIG. 1) JP-A-1-165181 (page 2, FIG. 1)

  As described above, when a three-branch optical waveguide is used, light from light sources of three colors of red (R), green (G), and blue (B) can be combined. When trying to obtain a white light source in which the three primary color lights of G, B are balanced, the following problems arise.

  Of the three branched optical waveguide core portions 61R, 61G, and 61B, the central core portion 61G has a straight core portion, so that the loss of propagating light is small. In 61B, the light 68 leaking to the clad due to the bending of the core portion increases, and the loss of propagating light increases. Therefore, considering the propagation efficiency of the light captured at the incident end face being taken out at the exit end face, the propagation efficiency of the central core portion 61G is high, and the propagation efficiency of the upper and lower core portions 61R and 61B is low.

  If the intensity ratio is adjusted so that the three primary colors of red light 66R, green light 66G, and blue light 66B taken into the light incident end face 63 can form beautiful white, this difference in propagation efficiency is different. Therefore, in the outgoing light 67, the intensity of the green light 66G becomes too strong, the intensity of the red light 66R and the blue light 66B becomes too weak, the ratio of the three primary color lights changes, and beautiful white color cannot be formed.

  FIG. 3 shows emission spectra of red, green, and blue light emitting diodes, which will be described later, and actual three primary color light sources have different characteristics. Therefore, high-quality white light cannot be obtained by simply combining the three primary color lights as in the conventional three-branch optical waveguide. In order to obtain good-quality white light, the three-branch type optical waveguide is required to have a function of combining while adjusting the intensity ratio of the three primary color lights. As in this example, in practice, the efficiency of extracting from each optical waveguide as the output light combined with the light emitted from each light source corresponds to the emission characteristics of each light source and the desired combined light properties, A branched optical waveguide that can be changed for every three optical waveguides is desirable.

  Another problem relates to miniaturization. FIG. 11 is a graph showing the relationship between the core length d and the light loss when the three primary color lights are combined using a three-branch optical waveguide. This graph was obtained by simulation under the same conditions as in Embodiment 1 of the present invention described later. From this graph, it can be seen that if the length d of the core is made too small, the loss increases rapidly. This is considered to be because if the core length d is made too short, a curved portion with a large curvature is generated in the core portion, and light easily leaks from here to the clad 62 as shown by the dotted line in FIG. . If the light 68 leaking to the clad 62 increases, not only is the light lost, but the leaked light 68 becomes stray light, disturbing the outgoing light 67 from the light source module, and the quality as a light source is lowered.

  For this reason, conventionally, the allowable range of loss due to leakage has been determined to be 2 dB, for example. For example, assuming that LEDs having a width of 400 μm are arranged without a gap and assuming that the pitch between the LEDs is 400 μm, from FIG. 11, in order to suppress the loss to the allowable range of 2 dB, the length d of the optical waveguide is set to It turns out that it is necessary to take 20 mm or more. Thus, the miniaturization of the light source module is limited by the allowable range of loss.

  Because of this difficulty, it is an LED module that can be used as a point light source that generates white light by combining RGB light, and is small, easy to mount, low in cost, such as a head mounted display. An LED module suitable for a light source has not been realized yet.

  The present invention has been made in view of such a situation, and an object thereof is a branched optical waveguide that takes in light from a plurality of light sources arranged opposite to a plurality of optical waveguides, and outputs the combined light. A branched optical waveguide that can emit combined light including light from the plurality of light sources at a predetermined ratio and can be downsized, a light source module using the branched optical waveguide, and an optical information processing apparatus such as a display Is to provide.

The present invention comprises a joined body of a core and a clad, wherein the core is divided into a plurality of core portions, and light from a light source disposed to face each of the light incident end faces of the plurality of core portions, In the branched optical waveguide, each taken into the core part facing the light source, combined, and output from the light output end face of the combined core part,
When the light from the light source is combined after being incident on each of the plurality of core portions, the light intensity and / or the amount of light of the combined light is a predetermined ratio between the plurality of core portions, The geometrical shapes of the plurality of core portions are respectively set, and the present invention relates to a branched optical waveguide.

  In the light source module, a plurality of light sources are arranged on the light incident end face of the branched optical waveguide, and light incident on the light incident end face from the plurality of light sources is combined and emitted from the light emitting end face. In addition, the present invention also relates to an optical information processing apparatus having the branched optical waveguide, an incident means for entering signal light into the optical waveguide, and a light receiving means for receiving light emitted from the optical waveguide.

  According to the branched optical waveguide of the present invention, the geometric shapes of the plurality of core portions, for example, the planar inclination angles and cross-sectional sizes of the plurality of core portions up to the combined core portion, etc. Thus, the light propagation efficiency in the plurality of core portions and the light capture efficiency from the plurality of light sources on the light incident end face are adjusted for each of the plurality of core portions. For this reason, the light from the plurality of light sources is not combined with the light intensity emitted from the plurality of light sources, but the light intensity and / or light amount of the combined light is predetermined. After being adjusted to a ratio, it is combined. For this reason, the light containing the light from the plurality of light sources in the ratio of the predetermined light intensity and / or the amount of light can be emitted as combined light without being influenced by the characteristics of the plurality of light sources. For example, it is possible to form beautiful white light in which the three primary color lights are contained in an appropriate ratio even from three primary color light sources of red light, green light, and blue light having different light intensities and / or light quantities.

  At this time, if a method of actively utilizing light leakage from the plurality of core portions to the clad is taken, the length of the branched optical waveguide, which has been conventionally limited to suppress light leakage, is further increased. It is also possible to shorten it.

  In addition, since the light source module of the present invention uses the branched optical waveguide for multiplexing light from the plurality of light sources, the light from the plurality of light sources has a predetermined light intensity and / or ratio of the amount of light. The contained light can be extracted from the light emitting end face. For example, it is possible to form a small white light source using three primary color light LEDs.

  Further, the optical information processing apparatus of the present invention is constituted by the branched optical waveguide, signal light incident means to the branched optical waveguide, and light receiving means for light emitted from the optical waveguide. The color information of the signal light can be correctly transmitted to the light receiving means, and the color light of the signal light is corrected by the branched optical waveguide, or the color information is processed. Law is also possible.

  In the branched optical waveguide of the present invention, the core portion disposed opposite to the light source having a small light output corresponding to the light output of the light source is combined with the light taken from the light incident end face. The propagation efficiency, which is the ratio of the light intensity to the light and / or the amount of light, should be set large. Thereby, the difference in the light output for each light source can be reduced. For example, red light, green light, and blue light having different light intensity and / or light amount by making the light intensity and / or light amount of the combined light equal among the plurality of core portions. Even from these three primary color light sources, it is possible to form beautiful white light that contains the three primary color lights equally.

  Further, as the light output, peak wavelength intensity may be used or area intensity in consideration of the full width at half maximum of the peak wavelength may be used depending on the usage situation.

  In addition, the geometric shape of the plurality of core portions is a planar inclination angle of the core portion up to the combined core portion (for example, the curvature of the curved portion), and the light source having a small light output is used. It is preferable that the inclination angle is set to be smaller as the core portions are arranged to face each other. When the inclination angle is reduced, light propagating through the core part can be prevented from leaking to the cladding, and propagation loss in the core part can be reduced. Conversely, when light leakage from the core portion to the clad is actively used to adjust the light intensity and / or light amount, the inclination angle (for example, the curvature of the curved portion) is increased appropriately. It is good to do.

  Moreover, the cross-section may be set larger as the core portion is arranged to face the light source having a smaller light output. As a method for enlarging the cross section, it is easy in manufacturing to increase the width of the cross section, but the height may be changed. By enlarging the cross section, it is possible to increase the efficiency with which light from the light source is taken into the core portion from the light incident end face.

  In addition, the light incident end surface has an inclined reflection surface, and the light from the light source disposed on the bottom surface side of the core portion is reflected by the inclined reflection surface and then travels toward the light emitting end surface. It may be configured. If it does in this way, there exists a merit which a new freedom degree produces in the mounting position and mounting method of a light source, such as sticking light sources, such as LED, to the surface direction lower part of an optical waveguide. In addition, the efficiency with which the light from the light source is taken into the core portion from the light incident end face can be changed by changing the inclination of the inclined reflecting surface.

  The branched optical waveguide is preferably made of a polymer material, particularly a photocurable resin. This is because by using an organic material as the material of the optical waveguide, the optical waveguide manufacturing process can be simplified as compared with the case of using a conventional silica-based optical waveguide. For example, when a photo-curing resin is used, a film can be formed by spin coating or the like, and then core processing can be easily performed and patterned by exposure and development by photolithography. Thus, it becomes possible to produce an optical waveguide with an inexpensive equipment investment and a low manufacturing cost, which is advantageous as a cladding material.

  Examples of such a photocurable resin include polymer organic materials such as oxetane resins described in JP-A No. 2000-356720. Such a polymer organic material preferably transmits 90% or more of visible light having a wavelength of 390 nm or more and 850 nm or less. In addition to the photocurable resin, an inorganic material may be used for the core material or the clad material.

  As described above, as the optical waveguide material, an oxetane resin composed of an oxetane compound having the following oxetane ring or a polysilane composed of an oxirane compound having the following oxirane ring can be used. A composition containing a cationic polymerization initiator capable of initiating polymerization by reaction is preferably used.

  Then, the present invention provides a display configured so that a signal beam that is efficiently condensed into a predetermined light flux by an optical waveguide and emitted, or signal light emitted after being efficiently incident on the optical waveguide is scanned and projected by a scanning unit. The signal light can be effectively used for optical information processing such as optical communication configured to make the signal light incident on a light receiving element (such as an optical wiring or a photodetector) of the next stage circuit.

  In the light source module of the present invention, when a display or the like is used, a light emitting diode is preferably used as the light source. In addition, when an optical wiring is intended, a laser diode is preferably used. Further, when a light source that emits red light, green light, and blue light is used, a white light source (RGB light) used for full-color display or the like can be obtained.

  The optical information processing apparatus according to the present invention may be configured as a display on which the emitted light is scanned by a scanning unit and projected.

  Next, a preferred embodiment of the present invention will be described specifically and in detail with reference to the drawings, using a three-branch optical waveguide as an example of the branch optical waveguide.

Embodiment 1
FIG. 1A is a plan view of a three-branch optical waveguide 10 and a light source module using the same according to Embodiment 1 of the present invention. In the three-branch optical waveguide 10, as in the conventional three-branch optical waveguide 60 described above, one end of the red light core portion 1R, the green light core portion 1G, and the blue light core portion 1B is The red light incident end surface 3R, the green light incident end surface 3G, and the blue light incident end surface 3B are formed, respectively, and the other end is coupled to one multiplexing core portion 1C. An end portion of the multiplexing core portion 1 </ b> C forms a light emission end face 4. FIG. 1B is an exploded view of the core for easily explaining the shapes of the red light core portion 1R, the green light core portion 1G, and the blue light core portion 1B. While the green light core portion 1G has a linear shape, the red light core portion 1R and the blue light core portion 1B have an S-shape.

  On the light incident end faces 3R, 3G, and 3B, a red light source 5R, a green light source 5G, and a blue light source 5B are installed to face each other. The red light 6R, the green light 6G, and the blue light 6B incident on the light incident end surface 3 from each light source 5 travel through the red light core portion 1R, the green light core portion 1G, and the blue light core portion 1B, respectively. The light is guided to the multiplexing core portion 1 </ b> C and combined, and emitted from the light emitting end face 4 as spot-like white light 7.

  The light source 5 is not particularly limited, but it is preferable to use a light emitting diode. Here, considering the arrangement of the light emitting diodes on the light incident end face side, the pitch of each light incident end face is assumed to be 125 μm. The width of each core part is assumed to be constant at 50 μm.

  The optical waveguide including the core 1 (core portions 1R, 1G, 1B, and 1C) and the clad 2 that covers the core 1 can be formed of a polymer-based resin. For example, it is preferable to use the above-mentioned oxetane resin (manufactured by Sony Chemical Co.). Further, polysilane (trade name Gracia; manufactured by Nippon Paint Co., Ltd.) may be used. There are polymer materials having a refractive index suitable for the core 1 and the clad 2, and they can be obtained from the above manufacturers.

At this time, the core 1 is made to have a larger refractive index than the clad 2. For example, when the core 1 and the clad 2 are formed using an oxetane resin, the refractive index n ₁ of the core 1 is 1.543 and the refractive indices n _{2 of the} clads 2 and 3 are 1.516. Specific refractive index difference = (n ₁ −n ₂ ) / n ₁
The relative refractive index difference defined by is 1.7%.

  If the refractive index of the core 1 is larger than the refractive index of the cladding 2, the light once incident on the core 1 is difficult to leak into the cladding 2, and the light incident on the interface between the core 1 and the cladding 2 at a shallow angle is totally reflected. However, the light travels through the core 1 toward the light emitting end face 4.

  As described above, in the central optical waveguide core portion 1G, since the core portion is linear, most of the propagating light is totally reflected and the loss of light is small. However, in the core portion having the S-shaped curved shape such as the core portion 1B and the core portion 1R, when the curvature of the curved portion increases, the light incident at a deep angle on the boundary surface between the core 1 and the clad 2 The ratio of light that leaks to the clad 2 without being reflected by the surface and becomes a loss increases.

  FIG. 2 is a graph showing a result of calculating the relationship between optical loss and waveguide length when light propagates through an S-shaped optical waveguide having a curvature. The calculation was performed when the position of the light incident end face and the light exit end face was changed by 125 μm in the direction perpendicular to the light traveling direction in accordance with the three-branch optical waveguide 10. From FIG. 2, the loss tends to increase as the length of the waveguide decreases and the curvature increases.

  That is, when the length of the waveguide is 6.5 mm, the loss is about 2 dB, and when the length is shorter than this, the loss increases rapidly. Conventionally, such a large loss condition has not been noticed as being unacceptable. One of the features of the present embodiment is that the condition that increases the loss is positively used as a means for controlling the amount of light. The light leaking to the clad 2 may be dealt with separately by a method such as providing a light absorbing means in the clad 2 so as not to interfere with the emitted light 7.

  According to FIG. 2 and Table 1, when the length of the optical waveguide is 6 mm, there is a loss of about 2.4 dB (58% light is transmitted), and when the length of the optical waveguide is 5 mm, it is about 5 It can be seen that there is a loss of 1 dB (31% light is transmitted).

  FIG. 3 shows emission spectra of red, green, and blue light emitting diodes. The emission peak wavelengths are 644 nm for the red light emitting diode, 522 nm for the green light emitting diode, and 461 nm for the blue light emitting diode. By combining these three colors by the three-branch optical waveguide 10 and additively mixing them, visible light of any color can be reproduced.

  As the light emitting diode (LED), for example, a GaN green light emitting LED and blue light emitting LED can be used as the green light source 5G and the blue light source 5B. As the red light source 5R, an AlGaInP-based red light emitting LED can be used. A laser can also be used as the light source.

  Comparing the spectral intensity in FIG. 3 with the intensity at the peak wavelength, it can be seen that there is a relationship of green light: blue light: red light = 1: 2: 3. The current value at this time is constant at 15 mA.

  By using the branched optical waveguide 10 of the present embodiment for the light sources having different emission intensity ratios as described above, the emitted light 7 emitted from the light emitting end face 4 becomes green light, blue light, and red light. Can be included at a predetermined ratio. For example, in order to take out the emitted light 7 containing these three primary color lights at substantially the same intensity (ratio of green light: blue light: red light = 100: 116: 93), the following is performed.

  First, the green light source 5G having the lowest emission intensity is arranged at a position facing the central core portion 1G that is linear and has the smallest loss. The remaining two light sources, the blue light source 5B and the red light source 5R, are arranged at positions where the core portions oppose the upper and lower core portions having a curved shape. The intensity at the wave core is made the same as that of green light.

  That is, since blue light has twice the intensity of green light, it may be attenuated to about 50%. Therefore, in order to obtain the same intensity as that of the green light, it is only necessary to have a loss of about 2.4 dB. From the results of FIG. 2 and Table 1, the length of the S-shaped blue light core portion 1B is determined. 6 mm. Similarly, since red light has three times the intensity of green light, it may be attenuated to about 33%. Accordingly, in order to obtain the same intensity as that of green light, it is sufficient to have a loss of about 5 dB. Therefore, the length of the S-shaped red light core portion 1R is set to 5 mm.

  In this way, of the light taken into the cores from the light sources 5G, 5B and 5R, almost 100% of the green light is emitted from the light emitting end face 4, and 58% of the blue light is emitted from the light emitting end face 4. As a result, 31% of the red light is emitted from the light emitting end face 4. Since the ratio of the light output of each light source is green light: blue light: red light = 1: 2: 3, almost the same intensity from the light emitting end face 4 (green light: blue light: red light = 100: 116: 93) It can be seen that light including green light, blue light and red light can be extracted.

  FIG. 4 shows two methods for taking the light 6 from the light source 5 into the core 1 in the present embodiment. FIG. 4A shows a case where the light source 5 is disposed on the side portion of the optical waveguide. In FIG. 4B, the light incident end face 3a of the optical waveguide is formed in an inclined reflecting surface, and the incident light from the light source 5a arranged on the bottom surface side of the optical waveguide is reflected by the light incident end face 3a having the inclined reflecting surface. In this case, the light emitting end face 4 is directed toward the light emitting end face 4 after being formed. If it does in this way, there exists a merit which a new freedom degree produces in the mounting position and mounting method of a light source, such as sticking light sources, such as LED, to the surface direction lower part of an optical waveguide. At this time, the loss on the inclined reflecting surface was 3 dB (reflectance: 50%).

  FIG. 5 shows another example 10b of the three-branch type optical waveguide according to this embodiment. In the three-branch type optical waveguide 10b, the length of the red light core 1R is further shortened, the curvature is increased, the loss is increased, and the green light or It is adjusted to have the same intensity as blue light.

  As in the above-described example, in the three-branch optical waveguide 10 of the present embodiment, the planar portions of the core portions 1G, 1B, and 1R up to the combined core portion 1C corresponding to the light intensity of each light source 5 are obtained. Since the inclination angle (here, the curvature of the curved portion) is set and the propagation loss of light in each core portion 1 is adjusted, the light from each light source 5 has a predetermined light intensity and / or ratio of the amount of light. Can be obtained from the light exit end 4.

  The light source module of the present embodiment is a light source module that can extract light including red light, green light, and blue light at a predetermined ratio with a point light source. It is useful as a white light source when applied to a micro display or the like.

Embodiment 2
FIG. 6 is a plan view of a three-branch type optical waveguide 20 and a light source module using the same according to the second embodiment of the present invention. In the three-branch optical waveguide 20, as in the conventional three-branch optical waveguide 60, one end of each of the red light core portion 11R, the green light core portion 11G, and the blue light core portion 11B is red. A light incident end surface 13R, a green light incident end surface 13G, and a blue light incident end surface 13B are formed, and the other end is coupled to one multiplexing core portion 11C. The other end portion of the multiplexing core portion 11C forms a light emission end face 14.

  On the light incident end faces 13R, 13G, and 13B, a red light source 15R, a green light source 15G, and a blue light source 15B are installed to face each other. The red light 16R, green light 16G, and blue light 16B incident on the light incident end face 13 from each light source 15 travel through the red light core portion 11R, the green light core portion 11G, and the blue light core portion 11B, respectively. The light is guided to the multiplexing core portion 11 </ b> C, combined, and emitted from the light emitting end face 14 as spot-like white light 17.

  The optical waveguide composed of the core 11 (core portions 11R, 11G, 11B, and 11C) and the clad 12 that covers the core 11 can be formed of a polymer-based resin as in the first embodiment. For example, the above-mentioned oxetane resin (manufactured by Sony Chemical) or polysilane (trade name Gracia; manufactured by Nippon Paint Co., Ltd.). Further, as in the first embodiment, the light source 15 is not particularly limited, but it is preferable to use a light emitting diode. Here, it is assumed that three types of light-emitting diodes having the same emission intensity ratio of green light: blue light: red light = 1: 2: 3 are used as in the first embodiment.

  By using the branched optical waveguide 20 of the present embodiment for the light sources having different emission intensity ratios as described above, the emitted light 17 emitted from the light emission end face 14 is similar to that of the first embodiment. It is possible to include green light, blue light, and red light at a predetermined ratio.

  The difference from the first embodiment is that, similarly to the conventional example, the red light core portion 11R and the blue light core portion 11B are S-shaped optical waveguides having the same length, and hence the same curvature. This is to make the width of the core part different. For example, a method of taking out the emitted light 17 in which the three primary color lights are included at a ratio of green light: blue light: red light = 1: 1: 1 will be described below.

  Similar to the first embodiment, the loss in the red light core portion 11R and the blue light core portion 11B can be positively utilized in the present embodiment, but here, in order to simplify the description, It is assumed that not only the green light core portion 11G but also the light propagation loss in the S-shaped red light core portion 11R and the blue light core portion 11B is suppressed to a negligible level. That is, according to Table 1, for example, the loss when the length is 13 mm is 20%. Therefore, the length of the core portion is further increased here, and the red light core portion 11R and the blue light core portion 11B. It is assumed that the loss is 10% or less and is negligible. Moreover, the height of each core part shall be the same. In such a case, in this embodiment, the ratio of the intensity of the light source, green light: blue light: red light = 1: 2: 3, the width of the core portion, the inverse ratio thereof, the green light core Part 11G: Blue light core part 11B: Red light core part 11R = 6: 3: 2.

  Thereby, the ratio of the area of the light incident end face 13 becomes green light incident end face 13G: blue light incident end face 13B: red light incident end face 13R = 6: 3: 2, and the light from each light source 15 has its light incident end face. The efficiency taken into the core 11 at 13 is also proportional to this.

  The amount of light actually taken into the core 11 from the light incident end face 13 is determined by the product of the intensity of the light source 15 and the above-mentioned taking efficiency. Therefore, when set as described above, the amount of light taken into the core 11 is equal for the three primary color lights. Become. If the subsequent loss in the core portion 11 can be ignored, the same amount of green light, blue light, and red light is also included in the light 17 emitted from the light emitting end face 14.

  As in the above-described example, in the three-branch optical waveguide 20 of the present embodiment, the size of the cross section of the core portion 11, usually the width of the core portion 11, is set corresponding to the light intensity of each light source 15. Therefore, the emitted light 17 in which the light from each light source 15 is included at a predetermined light intensity and / or light quantity ratio can be obtained from the light emitting end 14.

  The light source module of the present embodiment is a light source module that can extract light including red light, green light, and blue light at a predetermined ratio with a point light source. It is useful as a white light source when applied to a micro display or the like.

Embodiment 3
FIG. 7 is a plan view of a three-branch optical waveguide 30 and a light source module using the same according to the third embodiment of the present invention. In the three-branch optical waveguide 30, as in the conventional three-branch optical waveguide 60, one end of each of the red light core portion 21R, the green light core portion 21G, and the blue light core portion 21B is red. A light incident end surface 23R, a green light incident end surface 23G, and a blue light incident end surface 23B are formed, and the other end is coupled to the end of one multiplexing core portion 21C. The other end portion of the multiplexing core portion 21 </ b> C forms a light emission end face 24.

  On the light incident end faces 23R, 23G, and 23B, a red light source 25R, a green light source 25G, and a blue light source 25B are installed to face each other. The red light 26R, the green light 26G, and the blue light 26B incident on the light incident end face 23 from each light source 25 travel through the red light core portion 21R, the green light core portion 21G, and the blue light core portion 21B, respectively. The light is guided to the combining core portion 21 </ b> C, combined, and emitted from the light emitting end face 24 as spot-like white light 27.

  The optical waveguide composed of the core 21 (core portions 21R, 21G, 21B, and 21C) and the clad 22 covering the core 21 can be formed of a polymer-based resin as in the first embodiment. For example, the above-mentioned oxetane resin (manufactured by Sony Chemical) or polysilane (trade name Gracia; manufactured by Nippon Paint Co., Ltd.). As in the first embodiment, the light source 25 is not particularly limited, but a light emitting diode is preferably used. Here, it is assumed that three types of light-emitting diodes having the same emission intensity ratio of green light: blue light: red light = 1: 2: 3 are used as in the first embodiment.

  By using the branched optical waveguide 30 of the present embodiment for the light sources having different emission intensity ratios as described above, the emitted light 27 emitted from the light emitting end face 24 is obtained as in the first embodiment. It is possible to include green light, blue light, and red light at a predetermined ratio.

  A feature of the present embodiment is that a core portion shorter than the red light core portion 1R and the blue light core portion 1B used in the first embodiment is used as the red light core portion 21R and the blue light core portion 21B. Therefore, the aim is to further reduce the size of the branched optical waveguide and the light source module. When such a short core portion is used, the loss in the S-shaped optical waveguide is further increased, and red light and blue light included in the outgoing light 27 emitted from the light outgoing end 24 are less than green light as it is. End up. In order to make up for this shortage, in the present embodiment, the cross sections of the red light core portion 21R and the blue light core portion 21B are made larger than the cross section of the green light core portion 21G. In order to extract the emitted light 27 in which the three primary color lights are contained in a ratio of green light: blue light: red light = 1: 1: 1, for example, the following is performed.

  First, corresponding to the intensity ratio of the light source, blue light: red light = 2: 3, the widths of the blue light core portion 21B and the red light core portion 21R core portion are set to their inverse ratios, the blue light core portion. 21B: The red light core 21R is set to 3: 2. In this way, the same amount of blue light and red light from each light source is taken into the blue light core portion 21B and the red light core portion 21R, respectively, so that the blue light core portion 21B and the red light core portion are captured. An optical loss equal to that of the portion 21R is allowed and can be the same length.

  Next, the widths of the green light core portion 21G and the red light core portion 21R are set so that the red light core portion 21R is larger. In this way, the ratio of the amount of red light and green light taken into the core portion 21 is larger than that of the same width, so that a larger loss is allowed in the red light core portion 21R. Become. For example, when the green light core 21G: red light core 21R = 1: 2 is set, the ratio of the amount of red light and green light taken into the core 21 takes into account the difference in intensity of the light source. , Red light / green light = (3 × 2) / (1 × 1) = 6/1, and red light / green light = (3 × 1) / (in the case of the same width (for example, the first embodiment). Since 1 × 1) = 3/1, a loss twice as large is allowed. In this case, if the red light core portion 21R is set to a length that attenuates red light to 1/6 and transmits about 17%, the amount of red light in the combined core portion is made equal to the amount of green light. be able to. According to Table 1, since the length corresponding to the transmittance of 31% was 5 mm, in this embodiment, the red light core portion 21 </ b> R can be made much shorter than 5 mm. The same applies to the blue light core portion 21B. As in this example, when the width of the core portion of the S-shaped optical waveguide is widened to increase the amount of captured light, a shorter optical waveguide corresponding to a large loss can be used. It can be downsized.

  Other features are the same as those of the first and second embodiments. In the three-branch optical waveguide 30 of the present embodiment, the light from each light source 25 is included at a predetermined light intensity and / or light quantity ratio. The incident light 27 can be obtained from the light emitting end 24. The light source module of the present embodiment is a light source module that can extract light including three colors of red light, green light, and blue light at a predetermined ratio with a point light source, and is applied to a micro display or the like. It is useful as a white light source or the like.

Embodiment 4
FIG. 8 is a plan view of a three-branch optical waveguide 40 and a light source module using the same according to Embodiment 4 of the present invention. In the three-branch optical waveguide 40, the green light core portion 31G and the multiplexing core portion 31C form a linear core portion, and the linear red light core portion 31R and the blue light core portion 31B are formed thereon. And so that they cross each other from an oblique direction.

  On the red light incident end surface 33R, the green light incident end surface 33G, and the blue light incident end surface 33B, a red light source 35R, a green light source 35G, and a blue light source 35B are installed to face each other. The green light 36G incident on the green light core 31G from the green light source 35G and the red light 36R and blue light 36B incident on the red light core 31R and the blue light core 31B from the red light source 35R and the blue light source 35B, respectively. The light is combined by the combining core portion 31 </ b> C and emitted from the light emitting end face 34 as spot-like white light 37.

  The optical waveguide including the core 31 (core portions 31R, 31G, 31B, and 31C) and the clad 32 that covers the core 31 can be formed of a polymer-based resin as in the first embodiment. For example, the above-mentioned oxetane resin (manufactured by Sony Chemical) or polysilane (trade name Gracia; manufactured by Nippon Paint Co., Ltd.). Further, as in the first embodiment, the light source 35 is not particularly limited, but it is preferable to use a light emitting diode. Here, it is assumed that three types of light-emitting diodes having the same emission intensity ratio of green light: blue light: red light = 1: 2: 3 are used as in the first embodiment.

  By using the branched optical waveguide 40 of the present embodiment for the light sources having different emission intensity ratios as described above, the emitted light 37 emitted from the light emission end face 34 is similar to that of the first embodiment. It is possible to include green light, blue light, and red light at a predetermined ratio.

The difference from the first embodiment is that, in the three-branch type optical waveguide 10, the propagation loss of light in each core part 1 is adjusted by the curvature of the curved part of the core part 1, whereas the three-branch type optical waveguide is used. In the waveguide 40, planar inclination angles of the red light core portion 31R and the blue light core portion 31B (here, the angles θ _R and θ _B formed by the core portion 31R and the core portion 31B and the combined core portion 31C). ), The propagation loss of light in each of the core portions 31R and 31B is adjusted. When the inclination angle θ _R or θ _B is increased, the red light or the blue light is incident on the boundary surface between the core and the clad of the multiplexing core portion 31C at a large incident angle, and the rate of leakage to the clad increases. As a result, the attenuation rate increases.

  As in the above-described example, in the three-branch optical waveguide 40 of the present embodiment, the planar inclinations of the core portions 31G and 31R up to the multiplexing core portion 31C corresponding to the light intensity of each light source 35. The angle (here, the angle between the core portions 31R and 31B and the core portion 31C) is set, and the propagation loss of light in each of the core portions 31R and 31B is adjusted, so that the light from each light source 35 is predetermined. The emitted light 37 included in the light intensity and / or light quantity ratio can be obtained from the light emitting end 34.

  The light source module of the present embodiment is a light source module that can extract light including three colors of red light, green light, and blue light at a predetermined ratio with a point light source, and is applied to a micro display or the like. It is useful as a white light source or the like.

Embodiment 5
The light source modules of the above-described embodiments are suitable as so-called point light sources, and the emitted light is suitable as signal light to the next stage with a reduced beam diameter. The present embodiment is an example in which such an optical waveguide as a point light source is applied to an optical information processing apparatus such as a display.

  For example, a red light source 41R, a green light source 41G, and a blue light source 41B each made of an LED are arranged to face the light incident surface 3 of the branched optical waveguide 10 shown in FIG. If necessary, a convex lens part is provided. The red signal light 42R (R), the green signal light 42G (G) and the blue signal light 42B (B) emitted from the light sources 41R, 41G and 41B of the respective colors are combined, and the desired beam diameter is the same as described above. Is condensed and emitted.

  Then, by controlling the intensity and color balance of the signal light of each color, the emitted light (R, G, and B) 43 is projected onto the next stage, for example, a screen as signal light having the target color information, and full color. A display capable of reproducing the image can be obtained. Here, since the branched optical waveguide 10 according to Embodiment 1 of the present invention is used, the color information of the signal light 42 can be correctly transmitted to the next stage. In addition, the propagation loss of each of the optical waveguides 1R, 1G, and 1B in the branched optical waveguide 10 is set to a desired size, and the color balance of the signal light is corrected and color information is processed. Can also be used.

  FIG. 9 shows an example in which such a display is applied to a head-mounted display (HMD) 50. The optical waveguide 10 having the structure shown in FIG. After the outgoing light 43 having a reduced beam diameter from each optical waveguide 10 is passed through a scanned image plane 44, the human eyeball 46 optically conjugate with the scanning plate A focal point (spot) is formed on the retina 47 by an optical lens 45 or the like. This image formation point is formed on the retina 47 for one line, and this is scanned on the retina in a direction perpendicular to the line by the scanning plate 44 so that a realistic image can be experienced personally. Can do.

  In such a display, the light emitted from the LEDs 41R, 41G, and 41B, which are light sources, generally has no coherency, has a wide radiation angle, and it is difficult to combine the three colors. As described above, since the light from the LED is introduced into the core of the optical waveguide 10 and can be condensed to a desired beam diameter by the convex lens portion at the end thereof, the light combined in the optical waveguide 10 functions as a point light source. However, this is very advantageous for display applications.

  The head mounted display 50 can be provided with a compact video device by being incorporated in a projector, a camera, a computer, a game machine or the like while being mounted like sunglasses.

  As described above, according to the embodiment of the present invention, a plurality of optical waveguides having different geometric shapes of the respective optical waveguides up to the multiplexing core portion are formed in the multiplexing core portion. A branched optical waveguide characterized by a structure that optically merges into one is used. The reason is that since the geometric shapes, for example, the curvatures of the respective optical waveguides are different, the losses of the respective optical waveguides are also different, so that the balance of the light sources having different characteristics can be adjusted.

  Therefore, the light emitting elements (LEDs, etc.) of the three primary colors of red light (R), green light (G), and blue light (B) having different emission characteristics are converted into three optical waveguides having different geometric shapes such as curvature. By appropriately arranging, light including the three primary color lights with the same light intensity in a well-balanced manner can be taken out from the combined light exit end faces. The optical waveguide of the present invention can constitute a light source module that combines light sources of the three primary colors of red, green, and blue and can take out the combined light with a point light source of any size. This light source module can be applied to a micro display, a projector, an optical communication module, an optical interconnection, etc. as a three-color light source.

  As mentioned above, although this invention was demonstrated based on embodiment, it cannot be overemphasized that this invention is not limited to these examples at all, and can be suitably changed in the range which does not deviate from the main point of invention.

  The branched optical waveguide according to the present invention can be applied to a micro display light source, a projector light source, an optical interconnection, an optical communication module, and the like.

  For example, a display configured to multiplex and emit light from a plurality of signal sources at a ratio of a predetermined light intensity in a branched optical waveguide, and scan and project the emitted signal light with a scanning unit, The signal light can be effectively used for optical information processing such as optical communication configured to enter the light receiving element (optical wiring, photodetector, etc.) of the next stage circuit.

  The light beam emitted from the optical waveguide of the present invention can emit light from a minute core due to the tip shape of the optical waveguide. Therefore, the present invention can provide a light source module useful as a point light source of a micro display.

It is the top view (a) of an optical waveguide and a light source module based on Embodiment 1 of this invention, and explanatory drawing (b) which decomposed | disassembled and showed the core. It is a graph which shows the dependence of the optical loss with respect to the length of a waveguide at the time of transmitting an optical waveguide which has an S-shaped curvature similarly. It is the emission spectrum of a red, green, and blue light emitting diode. It is sectional drawing explaining two methods to send light from a light source to a core part similarly. It is a top view of another optical waveguide and a light source module. It is a top view of an optical waveguide and a light source module based on Embodiment 2 of the present invention. It is a top view of the other example of an optical waveguide and a light source module based on Embodiment 3 of this invention. It is a top view of an optical waveguide and a light source module based on Embodiment 3 of this invention. It is explanatory drawing of the head mounted display based on Embodiment 4 of this invention. It is a top view which shows the light source module which combines the light from the three-color light source of R, G, B using a 3 branch type | mold optical waveguide, and obtains a spot-shaped white light source. It is a graph which shows the relationship between the core length d and the loss of light in the case of combining red light, green light and blue light using a three-branch optical waveguide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Core part, 1R ... Core part for red light, 1G ... Core part for green light, 1B ... Core part for blue light,
2 ... clad, 3 ... light incident end face, 3a ... light incident end face having an inclined reflecting surface,
3R: Red light incident end face, 3G: Green light incident end face, 3B: Blue light incident end face,
4 ... Light emitting end face, 5 ... Light source, 5R ... Red light source, 5G ... Green light source, 5B ... Blue light source,
6 ... incident light, 6R ... red light, 6G ... green light, 6B ... blue light, 7 ... outgoing light (white light),
DESCRIPTION OF SYMBOLS 10 ... Three branch type | mold optical waveguide, 11 ... Core part, 11R ... Core part for red light,
11G ... Core for green light, 11B ... Core for blue light, 12 ... Clad,
13 ... light incident end surface, 13a ... light incident end surface having an inclined reflecting surface, 13R ... red light incident end surface,
13G: Green light incident end face, 13B: Blue light incident end face, 14: Light exit end face,
15 ... light source, 15R ... red light source, 15G ... green light source, 15B ... blue light source,
16 ... incident light, 16R ... red light, 16G ... green light, 16B ... blue light,
17 ... outgoing light (white light), 20 ... three-branch type optical waveguide, 21 ... core portion,
21R ... Red light core, 21G ... Green light core, 21B ... Blue light core,
22 ... cladding, 23 ... light incident end face, 23a ... light incident end face having an inclined reflecting surface,
23R: Red light incident end surface, 23G: Green light incident end surface, 23B: Blue light incident end surface,
24 ... light emitting end face, 25 ... light source, 25R ... red light source, 25G ... green light source,
25B ... Blue light source, 26 ... incident light, 26R ... red light, 26G ... green light,
26B ... blue light, 27 ... emitted light (white light), 30 ... three-branch type optical waveguide,
31 ... Core part, 31R ... Red light core part, 31G ... Green light core part,
31B ... Blue light core part, 32 ... Clad, 33 ... Light incident end face,
33a: Light incident end surface having an inclined reflection surface, 33R: Red light incident end surface,
33G: Green light incident end surface, 33B: Blue light incident end surface, 34: Light emitting end surface,
35 ... Light source, 35R ... Red light source, 35G ... Green light source, 35B ... Blue light source,
36 ... Incident light, 36R ... Red light, 36G ... Green light, 36B ... Blue light,
37 ... outgoing light (white light), 40 ... three-branch type optical waveguide, 41R ... red light source,
41G ... green light source, 41B ... blue light source, 42R ... red signal light, 42G ... green signal light,
42B ... blue signal light, 43 ... emitted light, 44 ... scanned image plane,
45 ... Optical lens, 46 ... Human eyeball, 47 ... Retina,
50 ... Head mounted display (HMD), 60 ... Three-branch type optical waveguide,
61 ... Core part, 61R ... Red light core part, 61G ... Green light core part,
61B: Blue light core part, 61C: Combined core part, 62: Cladding,
63R: Red light incident end surface, 63G: Green light incident end surface, 63B: Blue light incident end surface,
64: Light emitting end face, 65R: Color light source, 65G: Green light source, 65B: Blue light source,
66R ... red light, 66G ... green light, 66B ... blue light, 67 ... white light,
68 ... Light leaking into the cladding

Claims (14)

It consists of a joined body of a core and a clad, and the core is divided into a plurality of core portions, and light from a light source arranged facing each of the light incident end faces of the plurality of core portions faces the light source. In the branched optical waveguide, each taken into the core part, combined and emitted from the light exit end face of the combined core part,
When the light from the light source is combined after being incident on each of the plurality of core portions, the light intensity and / or the amount of light of the combined light is a predetermined ratio between the plurality of core portions, A branched optical waveguide, wherein the geometric shapes of the plurality of core portions are respectively set.   Corresponding to the light output of the light source, the light intensity and / or the amount of light of the light taken from the light incident end face and the combined light, as the core portion is arranged to face the light source having a small light output. The branched optical waveguide according to claim 1, wherein a propagation efficiency which is a ratio of is set to be large.   The branched optical waveguide according to claim 2, wherein the light intensity and / or light amount of the combined light is equal between the plurality of core portions.   The branched optical waveguide according to claim 1, wherein a peak wavelength intensity is used as the optical output.   The branched optical waveguide according to claim 1, wherein an area intensity considering a half width of a peak wavelength is used as the optical output.   The branched optical waveguide according to claim 2, wherein a geometric shape of the plurality of core parts is a planar inclination angle of the core parts up to the combined core part.   The branched optical waveguide according to claim 6, wherein the inclination angle is smaller as the core portion is arranged to face the light source having a smaller light output.   The branched optical waveguide according to claim 1, wherein the core portion disposed to face the light source having a small light output has a larger cross section.   The branched optical waveguide according to claim 1, wherein the branched optical waveguide is formed of a polymer material.   A plurality of light sources are arranged on the light incident end face of the branched optical waveguide according to claim 1, and light incident on the light incident end face from the plurality of light sources is combined to emit the light. A light source module emitted from the end face.   The light source module according to claim 10, wherein a light emitting diode or a laser diode is used as the light source.   The light source module according to claim 10, wherein a light source that emits blue light, green light, and red light is used as the light source.   An optical information processing apparatus comprising: the branched optical waveguide according to any one of claims 1 to 9; an incident means for entering signal light into the optical waveguide; and a light receiving means for receiving light emitted from the optical waveguide. .   The optical information processing apparatus according to claim 13, wherein the optical information processing apparatus is configured as a display on which the emitted light is projected by being scanned by a scanning unit.

Images