JP2005062444A - Optical waveguide and optical information processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide capable of efficiently condensing the light from a light source, and to provide an optical information device using this optical waveguide. <P>SOLUTION: The optical waveguide is characterized in that it consists of a 1st optical waveguide 7b having core layers 3b, 3c, and 3d narrowing in width from the side of incident light planes 5b, 5c, and 5d toward the side of outgoing light planes 6b, 6c, and 6d, and a 2nd optical wave guide 7a having a core layer 3a for obtaining outgoing radiation light of a predetermined size narrowing in width from the incident light plane 5a side toward the outgoing light plane 6a side; the outgoing light planes 6b, 6c, and 6d of a optical waveguide 7b are faced to the incident light plane 5a of the optical wveguide 7a; the optical waveguide 7a is located on the side of LED 9R, 9G, and 9B; the incident areas of the light from the LED 9R, 9G, and 9B are expanded in the directions of the thickness and width of the incident light plane 5a; and the outgoing light planes 6b, 6c, and 6d of the optical waveguide 7b exist within the same thickness area or a thinner area as the incident light plane 5a of the optical waveguide 7a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical information processing apparatus such as a light guide module, an optical waveguide, a display, and the like, which includes a joined body of a core layer and a clad layer, and is suitable for a light source module, optical interconnection, optical communication, and the like.

  Until now, information transmission over a relatively short distance, such as between boards in an electronic device or between chips in a board, has been carried out mainly by electrical signals, but in order to improve the performance of integrated circuits, And high-density signal wiring are required. 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 and noise generation due to the time constant of the wiring.

  Optical wiring (optical interconnect cushion) that solves these problems has attracted 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 used for transmission of signals over a short distance such as between chips. It is possible to construct an optical transmission and communication system in which an optical waveguide is formed on a substrate on which it is mounted, and a signal modulation laser beam or the like is used as a transmission path.

  On the other hand, it is also known to use an optical waveguide as a light source module of a display. For example, the development of a head mounted display that allows you to enjoy video software, games, computer screens, movies, etc. on your own day screen has been developed. There is a personal display that can be easily felt anywhere (see US Pat. No. 5,467,104).

  Red, green and blue light emitting diodes (LEDs) are used as the light source for this head mounted display, but the LED light is not coherent, has a wide radiation angle, and is condensed to combine the three colors. Is difficult. Therefore, a technique is known in which three types of LED light are combined through an optical waveguide to create uniform white light (Nikkei Electronics 2003.3.31, p127).

  An optical waveguide 58 as shown in FIG. 22 is also known (see Patent Document 1 described later).

  As shown in FIGS. 22A and 22B, the optical waveguide 58 is formed on an InP substrate 51 having a predetermined thickness made of a semiconductor substrate or a dielectric substrate, for example, on a lower portion made of InP having a thickness of 0.5 μm. A clad layer 52 is formed, and a core layer 53 made of InGaAs having a linear inclined surface 57 having a width of 50 μm on the incident surface 55 side and a width of 2 μm on the output surface 56 side is formed thereon. .

  Then, for example, an upper clad layer made of InP having a thickness of 1 μm is formed so as to cover the lower clad layer 52 and the core layer 53, and the optical waveguide 58 is configured.

  Then, as shown in FIG. 22 (c), for example, a laser 59 (any color) as a light source is disposed on the incident side of the optical waveguide 58 on the lower cladding layer 52, and light emitted from the laser 59 is emitted. When the beam is incident on the core layer 53 from the incident surface 55, the light beam is condensed so that the spread of the core layer 53 becomes narrow as the width of the core layer 53 changes, and then is emitted to the outside from the emission surface 56. .

JP-A-5-173036 (page 2, right column, line 17 to page 3, left column, line 8; FIGS. 1d and 1e)

  However, in the conventional example shown in FIG. 23, the optical waveguide 58 in which the core layer 3 has a trapezoidal shape in the width direction (horizontal direction) and the thickness direction (vertical direction) does not receive light incident in the width direction of the core layer 53. Although it is possible to collect light, it is difficult to increase the light collection efficiency in the thickness direction of the core layer 53. Further, when the spot diameter is required to be the same thickness as the core layer 53, a sufficient thickness as the core layer 53 cannot be obtained, and the optical coupling efficiency to the optical waveguide 58 is poor. . That is, in the conventional optical waveguide shape, it is extremely difficult to increase the optical coupling efficiency to the core layer 53 that is the waveguide and to control the area of the emission surface 56 that is the spot diameter of the emitted light to an arbitrary size. Have difficulty.

  The present invention has been made in view of the above situation, and an object thereof is an optical waveguide capable of efficiently condensing light from a light source, and an optical information processing apparatus using the optical waveguide. Is to provide.

That is, the present invention provides an optical waveguide comprising a joined body of a core layer and a cladding layer.
A first optical waveguide having a core layer whose width is at least narrowed from the light incident surface side to the light emitting surface side; And a second optical waveguide having a core layer for obtaining the emitted light of
The light emitting surface of the first optical waveguide and the light incident surface of the second optical waveguide are opposed to each other,
The first optical waveguide is disposed on a light source side, and an incident area of light from the light source is enlarged in a width direction and / or a thickness direction of the light incident surface of the second optical waveguide;
The light emitting surface of the first optical waveguide is in the same thickness region as the light incident surface of the second optical waveguide or in a thickness region smaller than this. .

  The present invention also relates to an optical information processing apparatus including the above-described optical waveguide, a light source that inputs signal light to the optical waveguide, and a light receiving unit that receives light emitted from the optical waveguide.

  An optical waveguide according to the present invention has a first optical waveguide having a core layer whose width is at least narrowed from the light incident surface side to the light emitting surface side, and at least a width is narrowed from the light incident surface side to the light emitting surface side. And a second optical waveguide having a core layer for obtaining outgoing light of a predetermined size, and an incident area of light from a light source in the first optical waveguide is the light incident surface of the second optical waveguide. Is expanded in the width direction and / or the thickness direction (preferably both in the width direction and the thickness direction), so that light from the light source is incident on the light incident surface of the first optical waveguide with sufficient efficiency. be able to. In addition, since the light emitting surface of the first optical waveguide is present in the same thickness region as the light incident surface of the second optical waveguide or in a thickness region smaller than the same, the light emitting surface of the first optical waveguide is Condensed light that has entered and collected from the light incident surface into the core layer layer can be sufficiently incident on the light incident surface of the core layer layer of the second optical waveguide.

  As described above, since the incident area of the first optical waveguide is large, tolerance at the time of alignment with the light source is large, and simple passive alignment is possible. Further, by arranging a plurality of light sources along the end face of the first optical waveguide, signals from the plurality of light sources can be efficiently collected.

  In addition, by providing a light source that makes signal light incident on the optical waveguide and a light receiving means that receives the emitted light from the optical waveguide, the above-mentioned optical waveguide has a large amount of light and can emit emitted light having a desired spot size. The optical information processing apparatus can be configured by using it.

  In the present invention, in order to make the outgoing light emitted from the light emitting surface of the core layer of the first optical waveguide sufficiently incident on the light incident surface of the core layer of the second optical waveguide, It is desirable that the light emitting surface of the core layer of one optical waveguide and the light incident surface of the core layer of the second optical waveguide are arranged so as to intersect each other.

  In addition, in order to sufficiently allow light from the light source to enter the core layer of the first optical waveguide, the core layer of the first optical waveguide has a plurality of layers, and the width of the light incident surface of the second optical waveguide. It is desirable to increase the area of the incident surface by laminating in the direction, and in order to make the outgoing light from the first optical waveguide sufficiently incident on the core layer of the second optical waveguide, the first optical waveguide It is desirable that the light emitting surface is divided into a plurality of portions in the width direction of the light incident surface of the second optical waveguide.

  In order to allow light from the light source to enter sufficiently, it is desirable that the light incident surface of the core layer of the first optical waveguide is expanded in the width direction of the light incident surface of the second optical waveguide. .

  Further, in order to effectively reflect the incident light incident on the first optical waveguide and the second optical waveguide to the inside of the core layer on a linear inclined surface, and to collect the reflected light on the light emitting surface In at least one of the core layers of the first optical waveguide and the second optical waveguide, the end surface in the width direction of the core layer is linearly inclined so that the width of the core layer becomes narrower toward the light emitting surface. It is desirable.

  In addition, at least one of the light sources may be disposed in the width direction of the light incident surface of the first optical waveguide, and the light incident surface of the core layer of the first optical waveguide may be a plurality of the light sources. May be incident simultaneously.

  Further, at least a light incident portion of the core layer of the first optical waveguide may be divided according to the number of the light sources.

  The core layer is preferably formed on the lower cladding layer in at least one of the first optical waveguide and the second optical waveguide.

  In this case, an upper clad layer may be formed from the core layer to the lower clad layer.

  In addition, light from a light source such as a light emitting diode or laser light can be collected by the first and second optical waveguides.

  The core layer is preferably formed of a photocurable resin. This is because it is easy to pattern the core layer corresponding to the exposure pattern by irradiation with light (particularly ultraviolet rays), and it is also advantageous as a constituent material of the cladding layer. Examples of such a photocurable resin include high molecular organic materials such as oxetane resins described in JP 2000-356720 A. Such a high molecular weight organic material preferably transmits 90% or more of possible visible light having a wavelength of 390 nm or less. In addition to the photocurable resin, an inorganic material may be used for the core material or the clad material.

  Further, as the optical waveguide material, the above-mentioned oxetane resin composed of an oxetane compound having the following oxetane ring, or polysilane composed of the following oxirane compound having an oxirane ring can be used, but for these photocuring (polymerization). It is preferable to use a composition containing a cationic polymerization initiator capable of initiating polymerization by a chain reaction.

  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.

  Next, a preferred embodiment of the present invention will be specifically described with reference to the drawings.

First Embodiment As shown in FIGS. 1 to 4, the optical waveguide according to the present embodiment has an optical waveguide on the light source side of an optical waveguide (second optical waveguide) 7a that emits light having a desired spot diameter. The optical waveguide (first optical waveguide) 7b is arranged perpendicular to the position corresponding to the waveguide 7a.

  Regarding the structure of the optical waveguide 7b, which is the first optical waveguide, a lower cladding layer 2b having a predetermined thickness is formed on a substrate 1b having a predetermined thickness, and a first core layer 3b is formed on the lower cladding layer 2b. ing. The core layer 3b has an incident surface 5b having a predetermined thickness and the same width as the front width of the optical waveguide 7b, and a width region corresponding to the incident surface 5a of the core layer 3a of the optical waveguide 7a described later on the opposite surface. And a trapezoidal shape having a linear inclined surface 8b whose width linearly narrows along the light traveling direction from the incident surface 5b toward the output surface 6b. An upper clad layer 4b having a predetermined thickness is formed so as to cover the core layer 3b.

  Then, a core layer 3c having the same shape as the core layer 3b is formed on the upper clad layer 4b with a predetermined thickness, and an upper clad layer 4c having a predetermined thickness is formed so as to cover the core layer 3c. A core layer 3d having the same shape as the core layer 3c is formed on the layer 4c to a predetermined thickness, and an upper clad layer 4d having a predetermined thickness is formed so as to cover the core layer 3d. The core layers 3b, 3c, and 3d are stacked in the width direction of the optical waveguide 7a, which is the second optical waveguide, so that the amount of light incident from the light source can be increased and light can be effectively incident on the optical waveguide 7a. It is configured.

  In this structure, polymer materials having different refractive indexes are sequentially laminated on the substrate 1b to form a laminate of patterned core layers and clad layers. The refractive index of each core layer is greater than the refractive index of each cladding layer.

  In addition, regarding the structure of the optical waveguide 7a which is the second optical waveguide, a lower cladding layer 2a having a predetermined thickness is formed on a substrate 1a having a predetermined thickness, and a core layer 3a is formed on the lower cladding layer 2a. Yes. The core layer 3a has an incident surface 5a having a predetermined thickness and the same width as the front width of the optical waveguide 7a, and an exit surface 6a having a predetermined thickness and width located on the opposite surface of the front surface. A trapezoidal shape having a linearly inclined surface 8a whose width linearly narrows along the light traveling direction from the light emitting surface 6a toward the emitting surface 6a. An upper clad layer 4a having a predetermined thickness is formed so as to cover the core layer 3a.

  The two types of optical waveguides 7b and 7a configured in this way are sequentially arranged from the light source side and aligned so as to be orthogonal to each other, and the former light emitting surface and the latter light incident surface are joined, for example, It joins with adhesives, such as ultraviolet curing resin. Here, in the optical waveguide 7b close to the light source, each core layer is positioned in the vertical direction of the drawing, and in the optical waveguide 7a far from the light source, the core layer 3a is positioned in the horizontal direction of the drawing. Further, as shown by the oblique lines in the drawing, each exit surface of the optical waveguide 7b exists in the same width as or within the width of the entrance surface 5a of the optical waveguide 7a, and each of the core layers 3b, 3c and 3d. The thicknesses of the light exit surfaces 6b, 6c, 6d are the same as or smaller than the thickness of the entrance surface 5a of the core layer 3a of the optical waveguide 7a.

  Next, as shown in FIG. 2B, red light emitting diodes 9R (LED (R)), green light emitting diodes 9G (LED (G)), and blue light emitting diodes 9B (LED (B)) which are light sources. ) Is arranged in the vertical direction of the optical waveguide 7b, and light from each light source is incident on the core layers 3b, 3c and 3d from the incident surfaces 5b, 5c and 5d of the optical waveguide 7b, respectively. When incident in this way, as described later, each incident light is effectively reflected by the linear inclined surface 8b of each trapezoidal core layer, and leakage light from the core layer to the cladding layer is reduced. It is easy to totally reflect the light inside, and the waveguided light can be condensed in the width direction of the core layer toward each emission surface of each core layer.

  Since the optical waveguide 7b is configured as described above, the plurality of light sources 9R, 9G, and 9B can be sufficiently incident on the enlarged light incident surface, and these light sources are compared with the light incident surface. Can be arranged freely, and the tolerance of alignment increases.

  The light collimated and emitted from each exit surface of the optical waveguide 7b in the vertical direction of the drawing enters the core layer 3a from the entrance surface 5a of the optical waveguide 7a at the next stage, and this incident light is described later. The linearly inclined surface 8a is effectively totally reflected inside the core layer 3a, the leakage light from the core layer to the cladding layer is reduced, and the light guided in the core layer 3a is directed toward the exit surface 6a. It can be collimated in the layer width direction, condensed to a desired spot size, and emitted from the emission surface 6a.

  In this way, finally, the light can be condensed and emitted with a desired spot diameter and a sufficient amount of light in the horizontal and vertical directions (core layer width direction and thickness direction) of the optical waveguide.

  As shown in FIG. 2C, when the optical waveguides 7b and 7a are observed from the light source side as a front view, the light sources 9G, 9R, and 9B are juxtaposed in the vertical direction of the drawing. Since each of the long core layers is arranged every other via the upper cladding layers in the horizontal direction of the drawing, the light from each light source is efficiently incident on each of the core layers 3b, 3c, and 3d. In addition, the light guided in each core layer can be incident on the common core layer 3a of the optical waveguide 7a from the exit surfaces 6b, 6c, 6d without fail from the incident surface 5a. In order to reliably perform this incidence, it is desirable that each incident light region corresponding to each of the exit surfaces 6b, 6c, and 6d does not protrude in the thickness direction of the entrance surface 5a.

  FIG. 4E shows a rear view of the optical waveguides 7b and 7a as viewed from the light emitting side of the optical waveguide. It will be understood that the light collected in the core layer 3a of the optical waveguide 7a is emitted with a sufficient amount of light and a desired spot size through the emission surface 6a.

  5A is a perspective view of the optical waveguide 7b, FIG. 5B is a plan view of the optical waveguide 7b, FIG. 6C is a front view of the optical waveguide 7b, and FIG. 6D is an optical waveguide 7b. A rear view is shown.

  As shown in FIG. 7, after the core layer 3b having the linear inclined surface 8b is formed on the lower cladding layer 2b, a plurality of core layers are sandwiched between the plurality of upper cladding layers in the same manner as this. The optical waveguide 7b having any number of core layers can be freely formed.

  8A is a perspective view of the optical waveguide 7a, FIG. 8B is a plan view of the optical waveguide 7a, FIG. 9C is a front view of the optical waveguide 7a, and FIG. 9D is an optical waveguide. The rear view of 7a is shown.

  Next, with reference to FIG. 10 to FIG. 11, the above-described optical waveguide and a method for manufacturing the optical waveguide 7 a and 7 b will be described with respect to the optical waveguide 7 b with reference to a cross section taken along line A-A ′ of FIG. This manufacturing process is also applied to the manufacturing process of the optical waveguide 7a, and both are performed according to the method described in Japanese Patent Application Laid-Open No. 2000-356720.

  First, as shown in FIG. 10B, the thickness after curing the lower clad material 12b made of an organic material on a substrate 1b made of, for example, silicon shown in FIG. 10A is about 30 μm, for example. To form a layer of the lower clad material 12b.

  As the material of the lower clad material 12b, a photocurable resin is preferable. For example, an oxetane resin, polysilane, and a photocurable resin composition before the start of cationic polymerization are used, and this is heat-treated after coating.

  Next, as shown in FIG. 10 (c), the lower clad material 12b made of an organic material is irradiated on the entire surface of the lower clad material 12b by using, for example, an ultra-high pressure mercury lamp. Is cured.

  As a result, as shown in FIG. 10D, the lower cladding layer 2b having a refractive index of about 1.51 is formed. Note that when the lower cladding material 12b is completely cured, the refractive index increases by, for example, about 0.025.

  Next, as shown in FIG. 10 (e), for example, a photocurable resin composition similar to that described above is applied onto the lower cladding layer 2 b to form a layer of the core material 13 b.

  Next, as shown in FIG. 11F, the core material 13b is selectively irradiated with ultraviolet rays through a photomask 14 having an opening corresponding to the core layer pattern described above.

  As a result, as shown in FIG. 11G, the core material 13b is cured at the portion corresponding to the opening of the photomask 14, and the core layer 3a is formed in the pattern described above.

  Next, as shown in FIG. 11 (h), the uncured core material 13b that has not been irradiated with ultraviolet rays is dissolved and removed. Thereby, for example, the core layer 3b having a trapezoidal planar shape and a refractive index of about 1.56 can be formed.

  Finally, as shown in FIG. 11I, the upper cladding layer 4b is formed on the exposed surface of the lower cladding layer 2b and the core layer 3b by, for example, the same method as the method of forming the lower cladding layer 2b.

  By such a manufacturing process, the core layer 3b can be formed on the lower cladding layer 2b, and the optical waveguide 7b can be manufactured by repeating the process.

  Next, with reference to FIG. 12, the light incident on the optical waveguide 7b and the optical waveguide state will be described.

  FIG. 12A shows a state in which light from each of the LEDs 9R, 9G, and 9B is incident on the core layer 3b of the optical waveguide 7b at the same time and is emitted from the emission surface 6b. At this time, the width of the incident surface 5b is A (μm), the width of the exit surface 6b is B (μm), and the distance from the entrance surface 5b to the exit surface 6b is d (mm). The width of the core layer 3b is linearly reduced from the light incident surface to the light output surface by the linear inclined surface 8b. The linear inclined surface 8b improves the total reflection at the interface between the core layer and the clad layer, so that the light can be guided efficiently in the core layer.

  FIG. 12B shows a correlation characteristic between the length d (mm) from the incident surface 5b to the exit surface and the optical loss (dB). According to this, when the width B of the exit surface is fixed to 50 μm and the allowable optical loss of the optical waveguide 7b is set to 2 dB or less indicated by a broken line in the graph, the condition a in which the width A of the entrance surface is 200 μm In order for the optical loss to be 2 dB or less, the lower limit of the length d from the incident surface 5b to the exit surface 6b is about 0.7 mm, and under the condition b where the width A of the incident surface is 300 μm, the optical loss is 2 dB or less. In order to achieve this, the lower limit of the length d from the entrance surface 5b to the exit surface 6b is about 1.5 mm. Similarly, when the width A of the incident surface is increased as in the conditions c, d, and e, the lower limit of the length d from the incident surface 5b to the exit surface 6b is about 3.0 mm so that the optical loss becomes 2 dB or less. , There is a tendency to increase to about 6.8 mm and about 15.0 mm.

  From this result, when the width B of the exit surface 6b is constant, if the width A of the entrance surface 5b is narrowed to reduce the inclination angle of the linear inclined surface 8b, the optical loss can be suppressed to 2 dB or less and The length d from the surface 5b to the exit surface 6b can be made relatively short. Therefore, it can be seen that it is desirable to define the width A in order to reliably improve the optical waveguide efficiency by the linear inclined surface 8b. This applies not only to each core layer such as the core layer 3b of the optical waveguide 7b described above but also to the core layer 3a of the optical waveguide 7a.

  On the other hand, in the optical waveguide 7c shown in FIG. 13A, the core layer is divided into three types of core portions 28e, 28f, and 28g each formed of the curved inclined surface 16, and these light incident surfaces 5e, 5f, and The light sources 9R, 9G, and 9B are arranged on the 5g side, the core portions 28e and 28g are joined to the core portion 28f at the front of the light emission surface 6e, and light is emitted to the emission surface 6e through the common core portion 15. It is structured to guide and emit. Here, when the width of the exit surface 6e is fixed to 50 μm, the pitch between adjacent core portions is P (μm), and the distance from the entrance surfaces 5e, 5f and 5g to the exit surface 6e is d (mm). As shown in FIG. 13B, the correlation characteristic between the length d (mm) from the incident surfaces 5e, 5f and 5g to the exit surface and the optical loss (dB) is as shown in FIG. 13B.

  According to this, when the allowable optical loss of the optical waveguide 7c is set to 2 dB or less indicated by a broken line, the condition from the incident surfaces 5e, 5f, and 5g to the emission surface under the condition a in which the pitch P between adjacent core portions is 200 μm is set. The length d up to 6e is required to be about 6 mm or more. Similarly, if the pitch P between adjacent core portions is set to 400 μm and 600 μm, the length d from the entrance surfaces 5e, 5f and 5g to the exit surface 6e is about 20 mm. As described above, about 60 mm or more is required.

  From this result, even if the pitch P between the adjacent core portions is narrowed and the inclination angle of the curved inclined surface 16 of the core portions 28e and 28g is made gentle, the above-mentioned length d is set to suppress the optical loss to 2 dB or less. It is necessary to increase it to about 6 mm or more. This is because the leakage angle from the core layer to the cladding layer cannot be sufficiently suppressed because the inclination angle of the curved inclined surface 16 of the core portions 28e and 28g is still steep, so that the length d is increased. Otherwise, the inclined surface of the curved inclined surface 16 cannot be made gentle to reduce the light leakage.

  On the other hand, in the case of the optical waveguide 7b shown in FIG. 12, since the inclined surface 8b of the core layer 3b is linear, as long as the inclination angle (that is, the width A of the incident surface) is controlled, the core layer The total reflection at the interface between the cladding layer and the cladding layer is increased, the optical waveguide efficiency in the core layer is improved, and the optical waveguide length d can be reduced. In the optical waveguide 7c of FIG. 13, since the light incident surface is narrow, the degree of freedom of disposing each light source on the corresponding incident surface is small and the loss of the light incident amount is large, but in the optical waveguide 7b of FIG. Since the incident surface common to the respective light sources is formed over the width A, the light sources can be easily arranged and the amount of incident light is increased.

  Next, in the optical waveguide structure in which the optical waveguides 7b and 7a are orthogonal to each other as shown in FIG. 1A, the output surface of the optical waveguide 7a is controlled by controlling the intensity and color balance of the signal light of each color. The emitted light emitted from 6a is projected as a desired spot size and a sufficient amount of signal light onto the next stage, for example, a screen, and a display capable of reproducing a full-color image can be obtained.

  FIG. 14 shows an example in which such a display is applied to a head-mounted display (HMD) 20, and the combination structure of the optical waveguides 7b and 7a shown in FIG. Are arranged in a line, and the light of each color from the red light source 9R, the green light source 9G, and the blue light source 9B is combined for each unit pixel, and the emitted light 25 with a reduced beam diameter from the optical waveguide 7a is obtained. After passing through a scanned image plane 21, a focal point (spot) is formed on the retina 17 of the human eyeball 18 optically conjugate with the scanning plate 21 by an optical lens 19 or the like. ing.

  This image forming point is formed on the retina 17 for one line, and this is scanned on the retina 17 in a direction orthogonal to the line by the scanning plate 21 so that a realistic image can be experienced personally. be able to.

  In addition, this head mounted display 20 can provide a compact video apparatus by being incorporated in a projector, a camera, a computer, a game machine, or the like while being mounted like sunglasses.

  According to the present embodiment, the optical waveguide 7b having the core layers 3b, 3c, and 3d whose width is narrowed from the light incident surfaces 5b, 5c, and 5d toward the light emitting surfaces 6b, 6c, and 6d, and the light incident Since the optical waveguide is configured by the combination with the optical waveguide 7a having the core layer 3a for obtaining the outgoing light of a predetermined size, the width becomes narrower from the surface 5a side toward the light outgoing surface 6a side. A sufficient amount of light from the light sources 9R, 9G, and 9B enters the light incident surfaces 5b, 5c, and 5d to the waveguide 7b, and then enters the light incident surface 6a of the optical waveguide 7a. A sufficiently large amount of emitted light that is reduced to the size of can be obtained. In this case, in each of the optical waveguides 7b and 7a, incident light incident on each of the core layers 3b, 3c and 3d and 3a is directed toward the inside of each core layer due to the presence of the linear inclined surfaces 8b and 8a of each core layer. Since it is easy to totally reflect, the loss of light amount is reduced, and incident light is efficiently collected toward each light emitting surface 6b, 6c and 6d, 6a of each core layer, and an arbitrary amount of light is emitted from the emitting surface 6a with a sufficient amount of light. Output light collimated to the spot diameter can be obtained.

  Further, the incident surface of the optical waveguide 7b on which light from the light sources 9R, 9G, and 9B is incident is expanded in the width direction and the thickness direction of the light incident surface 5a of the optical waveguide 7a (that is, the incident area of the optical waveguide 7b). Therefore, the light from each of the light sources 9R, 9G, and 9B can enter the light incident surfaces 5b, 5c, and 5d of the optical waveguide 7b with low loss, and each light source for the optical waveguide 7b. 9R, 9G, and 9B can be easily aligned, and the tolerance is increased. Further, since the light emitting surfaces 6b, 6c and 6d of the optical waveguide 7b are present in the same thickness region as the light incident surface 5a of the optical waveguide 7a or in a thickness region smaller than this, the light incident surface of the optical waveguide 7b. The light that has entered the core layers 3b, 3c, and 3d from 5b, 5c, and 5d and is condensed can be sufficiently incident on the light incident surface 5a of the core layer 3a of the optical waveguide 7a.

Second Embodiment As shown in FIGS. 15 to 16, the optical waveguide according to the present embodiment has core layers 3h, 3i, and 3j each having an entrance surface that is divided into three with a predetermined width on the front surface thereof. And these core layers are each divided into three, and each divided core layer is an optical waveguide 7e having a structure in which they are merged and integrated before the common exit surface 6h, and the light source side of the optical waveguide 7a described above Other than the arrangement in the first embodiment, the second embodiment is the same as the first embodiment.

  As for the structure of the optical waveguide 7e, as shown in FIGS. 15A and 15B, a lower cladding layer 2b having a predetermined thickness is formed on a substrate 1b having a predetermined thickness, and on the lower cladding layer 2b, A core layer 5h divided into three is formed, and each of the divided core portions 28h is opposite to the incident surface 5h provided at three positions with a predetermined thickness and a predetermined width on the light source side of the optical waveguide 7e. An exit surface 6f having a width corresponding to the entrance surface 5a of the core layer 3a of the optical waveguide 7a described above is located on the surface. Each divided core portion 28h is linearly narrowed from each incident surface 5h toward the common exit surface 6f, and each of the three divided core portions 28h is common before the exit surface 6f. The structure is such that the core layer 27h merges.

  An upper clad layer 4e having a predetermined thickness covering the core layer 3h is formed. Similarly, a core layer 3i having the same shape as the core layer 3h is formed on the upper clad layer 4e, and a predetermined thickness covering the core layer 3i is formed. A core layer 3j having the same shape as the core layer 3i is formed on the upper clad layer 4f with a predetermined thickness, and an upper clad layer 4g with a predetermined thickness is formed to cover the core layer 3j. Each of the core layers 3h, 3i, and 3j has core portions 28h, 28i, and 28j having the same pattern shape, and these are laminated so that incident light from the respective incident surfaces 5h, 5i, and 5j is shared. The light is emitted from the surfaces 6f, 6g, and 6h.

  As shown in FIG. 15B, the light from the light source 9R is incident on the upper and lower three-stage incident surfaces 5h, 5i and 5j in the left column in FIG. 15A, and the core layers 3h, 3i and 3j is made incident on each. Similarly, the light from the light source 9G is incident on the core layers 3h, 3i, and 3j from the incident surfaces 5h, 5i, and 5j in the central row in FIG. ), The light is incident on the core layers 3h, 3i, and 3j from the incident surfaces 5h, 5i, and 5j in the right column.

  When light is incident on the respective incident surfaces of the core layers 3h, 3i, and 3j in this way, each incident light passes through the respective core portions 28h, 28i, and 28j of each core layer, and the linear inclined surface of each core layer. While being totally reflected at 8b, the light is collimated efficiently in the vertical direction of FIG. 1 toward each of the exit surfaces 6f, 6g and 6h with a sufficient amount in the same manner as described in the first embodiment. Can be emitted.

  The collimated emission light from the emission surfaces 6f, 6g, and 6h of the optical waveguide 7e is incident on the core layer 3a from the incident surface 5a of the optical waveguide 7a arranged orthogonally in the next stage. In the same manner as described above, it is possible to obtain outgoing light having a desired spot size collimated in the width direction.

  FIG. 16C is a front view of the above-described optical waveguide 7e observed from the light source side. Although not shown, the light source 9R includes the incident surfaces 5h, 5i and 5j in the left column of the core layers 3h, 3i and 3j. The light source 9G is disposed at a position corresponding to the incident surfaces 5h, 5i and 5j in the central row of the core layers 3h, 3i and 3j, and the light source 9B is disposed on the core layers 3h, 3i and 3j. It arrange | positions corresponding to the entrance planes 5h, 5i, and 5j of the right column.

  FIG. 16D shows a rear view of the light emission side of the optical waveguide 7e, and the light condensed in the core layers 3h, 3i and 3j is emitted through the emission surfaces 6f, 6g and 6h.

  Also in the present embodiment, light from each light source can be efficiently incident on each core layer mainly from the incident surfaces stacked in three stages. At this time, since the core layer at each stage is divided for each light source, light of each color can be incident on each core layer independently. Of course, it is easy to arrange each light source at a corresponding position.

  In addition, in this embodiment, the same operations and effects as described in the first embodiment are obtained.

Third Embodiment In the present embodiment, as shown in FIGS. 17 to 18, the first layer described above except that the core layer of the optical waveguide 7g is a single layer and its thickness is increased. This is the same as the embodiment.

  That is, the optical waveguide 7g has a structure in which the core layers 3b, 3c, and 3d of the optical waveguide 7b shown in FIG. 5 are integrated into a single core layer 3k (therefore, the cladding layers 4b and 4c are removed). And covered with a cladding layer 4h. As shown in FIG. 17A, in the optical waveguide 7g, a lower clad layer 2b having a predetermined thickness is formed on a substrate 1b having a predetermined thickness, and the core layer 3k formed on the lower clad layer 2b is: An incident surface 5k that is much thicker than the thickness of each core layer described above and has the same width as the front width of the optical waveguide 7g, and is positioned on the opposite surface to the incident surface 5a of the core layer 3a of the optical waveguide 7a described above. And an emission surface 6i having a predetermined thickness and a width corresponding to. The core layer 3k is formed in a trapezoidal shape having a linear inclined surface 8b whose width decreases linearly from the incident surface 5k toward the output surface 6i.

  FIG. 18B shows a plan view of the optical waveguide 7g together with the light sources 9R, 9G, and 9B, and FIG. 18C shows a front view of the optical waveguide 7g from the light source side. The light sources 9R, 9G, and 9B are juxtaposed at predetermined intervals in the lateral direction of FIG. 17 with respect to the incident surface 5k of the optical waveguide 7g.

  FIG. 18D shows a rear view of the optical waveguide 7g, and the light condensed in the core layer 3k of the optical waveguide 7g is emitted through the emission surface 6i.

  This optical waveguide 7g is combined orthogonally with the optical waveguide 7a shown in FIG. 1, and can be used for optical waveguide as described above.

  Instead, as shown in FIG. 19, an optical waveguide 7g having an incident surface 51 bonded to the exit surface 6i can be combined by arranging an optical waveguide 7g on the light source side as shown by a broken line. For example, the core layer 31 of the optical waveguide 7h includes an incident surface 5l having the same shape as the incident surface 5k of the optical waveguide 7g according to the shape of the exit surface 6i that is long in the thickness direction of the optical waveguide 7g. The shape in the width direction and the depth direction is the same as that of the core layer 3k of the optical waveguide 7g, but the thickness is reduced toward the emission surface 6j. Here, the optical waveguides 7g and 7h are not arranged orthogonally and can be arranged parallel to each other.

  In this case, the light condensed in the core layer 3k of the optical waveguide 7g is emitted through the exit surface 6i, and then enters the core layer 3l through the entrance surface 5l of the optical waveguide 7h. The light is condensed on the output surface 6j while being totally reflected by the linear inclined surface 8h in the thickness direction, and is output from the output surface 6j.

  FIG. 20 shows a mold that can be used to fabricate the optical waveguide 7h.

  In this molding, the lower mold 24 is provided with the substrate 1a provided with the lower clad layer 2a in advance, and a molding space 31A corresponding to the core layer 3l is formed between the lower mold 24 and the core material. The core layer 3l having a predetermined shape can be formed on the lower clad layer 2a by injecting and curing.

  According to the present embodiment, the light incident surface 5k of the optical waveguide 7g on the light source side is further enlarged as compared with the first embodiment described above, so that the light from the light source is more efficiently transmitted to the optical waveguide. 7 g can be incident.

  In addition, in this embodiment, the same operations and effects as described in the first embodiment are obtained.

Fourth Embodiment As shown in FIG. 21, the present embodiment is the same as that described above except that an optical waveguide 7i having a structure in which the upper cladding layer 4a is removed from the optical waveguide 7a in the first embodiment described above is used. This is the same as the first embodiment.

  In this optical waveguide 7i, when incident light from the optical waveguide 7b shown in FIG. 1 enters the core layer 3a of the optical waveguide 7i through the incident surface 5a, there is leakage light from the core layer 3a to the upper clad layer. Therefore, the light exit surface becomes a condensing surface having a shape pattern as shown in FIG. 21 (c), and the exit light is obtained with a sufficient amount of light mainly from the core layer 3a.

  In addition, in this embodiment, the same operations and effects as described in the first embodiment are obtained.

  The embodiment described above can be variously modified based on the technical idea of the present invention.

  For example, the constituent material and the layer configuration of the optical waveguide described above may be variously changed. For example, an inorganic material such as lithium niobate is used, formed as a core material on a substrate by CVD (chemical vapor deposition), and etched into a predetermined pattern using a resist mask. A core layer equivalent to the prepared core layer can be formed. Further, the lower clad layer and the upper clad layer may be formed in the same shape as the trapezoidal core layer. In particular, the number of laminated cores in the optical waveguide 7b may be 2 or more in order to improve the light collecting property, but it is desirable from the practical viewpoint to be 20 or less.

  Further, in the case of using a plurality of optical waveguides, the crossing direction of each optical waveguide is not limited to the orthogonal direction, and the arrangement and the like may be variously changed. Further, when connecting the optical waveguide, it may be bonded via an optical material whose refractive index is controlled, but in this case, it is preferable to prevent light leakage from the connecting portion.

  Further, the core shape of the optical waveguide is not limited to a type having a linear inclined surface at the end surface in the width direction, but may be a core layer having a curved inclined surface at the end surface in the width direction. The core layer may be produced by molding with a molding die as shown in FIG.

  Further, the configuration of the optical system including the above-described optical waveguide may be appropriately changed. For example, a micromirror device, a polygon mirror, or the like may be employed as a scanning unit, or projection may be performed on a screen.

  The present invention includes a display using an optical waveguide using an LED or a laser as a light source, for example, signal light from the optical waveguide using a laser is incident on a light receiving element (optical wiring, photodetector, etc.) of the next stage circuit. It can be widely applied to various optical information processing such as optical communication.

  The present invention relates to a display configured to scan and project the signal light emitted after being efficiently condensed into a predetermined light beam and emitted from the optical waveguide, or after being efficiently incident on the optical waveguide, The present invention can be effectively used for optical information processing such as optical communication configured to cause signal light to be incident on a light receiving element (such as an optical wiring or a photodetector) of the next stage circuit.

It is a perspective view (a) of the optical waveguide which consists of a combination of the 1st and 2nd optical waveguide by the 1st Embodiment of this invention. It is a plan view (b) and a front view (b) of the optical waveguide. It is a perspective view (d) of a core layer. It is a rear view (e) of the optical waveguide. FIG. 2 is a perspective view (a) and a plan view (b) of the first optical waveguide. FIG. 6 is a front view (c) and a rear view (d) of the second optical waveguide. FIG. 3 is a schematic exploded perspective view of a second optical waveguide in which a plurality of core layers are stacked. FIG. 6 is a perspective view (a) and a plan view (b) of the second optical waveguide. FIG. 6 is a front view (c) and a rear view (d) of the second optical waveguide. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide. FIG. 6 is a plan view (a) of the optical waveguide and a graph (b) showing the relationship between the optical loss and the incident surface width of the core layer. FIG. 6 is a plan view (a) of another optical waveguide and a graph (b) showing the relationship between the optical loss and the core interlayer pitch. It is a schematic model of a head mounted display. It is the perspective view (a) and its top view (b) of the 1st optical waveguide by the 2nd Embodiment of this invention. FIG. 2 is a front view (a) and a rear view (b) of the first optical waveguide. It is the perspective view (a) and its top view (b) of the 1st optical waveguide by the 3rd Embodiment of this invention. FIG. 2 is a front view (a) and a rear view (b) of the first optical waveguide. FIG. 6 is a perspective view of a core layer of an optical waveguide according to another example. It is sectional drawing of the shaping | molding die used for preparation of the core layer of an optical waveguide similarly. It is the perspective view (a) of the 2nd optical waveguide by the 4th Embodiment of this invention, its front view (b), and its rear view (c). It is the perspective view (a) of the optical waveguide by a prior art example, its sectional drawing (b), and its side view (c).

Explanation of symbols

1a, 1b ... substrate, 2a, 2b ... lower clad layer,
3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 3k, 3l ... core layer,
4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i ... upper clad layer,
5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, 5j, 5k, 5l ... incident surface,
6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j ... exit surface,
7a, 7h, 7i ... second optical waveguide,
7b, 7c, 7d, 7e, 7f, 7g, 7h, 7i ... first optical waveguide,
8a, 8b ... linear inclined surface, 9R, 9G, 9B ... light source, 17 ... retina, 18 ... eyeball,
19 ... Optical lens, 20 ... Head mounted display, 21 ... Scanning plate, 23 ... Upper mold,
24 ... Lower mold, 25 ... Emission light, 27h, 27i, 27j ... Common core layer,
28h, 28i, 28j ... Core part

Claims (13)

In an optical waveguide composed of a joined body of a core layer and a cladding layer,
A first optical waveguide having a core layer whose width is at least narrowed from the light incident surface side toward the light emitting surface side; and a predetermined size that is at least narrower from the light incident surface side toward the light emitting surface side. A second optical waveguide having a core layer for obtaining the emitted light of
A light exit surface of the first optical waveguide and a light incident surface of the second optical waveguide are opposed to each other;
The first optical waveguide is disposed on the light source side, and an incident area of light from the light source is enlarged in a width direction and / or a thickness direction of the light incident surface of the second optical waveguide;
The optical waveguide characterized in that the light exit surface of the first optical waveguide is present in the same thickness region as the light incident surface of the second optical waveguide or in a smaller thickness region.   2. The optical waveguide according to claim 1, wherein the light emitting surface of the core layer of the first optical waveguide and the light incident surface of the core layer of the second optical waveguide are arranged to intersect each other. .   A plurality of the core layers of the first optical waveguide are stacked in a width direction of the light incident surface of the second optical waveguide, and the light emitting surface of the first optical waveguide is the light incident of the second optical waveguide. The optical waveguide according to claim 2, wherein the optical waveguide is divided into a plurality of parts in the width direction of the surface.   The optical waveguide according to claim 2 or 3, wherein the light incident surface of the core layer of the first optical waveguide is expanded in a width direction of the light incident surface of the second optical waveguide.   In at least one of the core layers of the first optical waveguide and the second optical waveguide, an end surface in the width direction of the core layer is linearly inclined so that the width of the core layer becomes narrower toward the light emitting surface. The optical waveguide according to claim 1.   The optical waveguide according to claim 1, wherein at least one of the light sources is disposed in a width direction of the light incident surface of the first optical waveguide.   The optical waveguide according to claim 1, wherein the light incident surface of the core layer of the first optical waveguide simultaneously receives light from the plurality of light sources.   The optical waveguide according to claim 1, wherein at least a light incident portion of the core layer of the first optical waveguide is divided according to the number of the light sources.   The optical waveguide according to claim 1, wherein the core layer is formed on a lower cladding layer in at least one of the first optical waveguide and the second optical waveguide.   The optical waveguide according to claim 9, wherein an upper clad layer is formed from the core layer to the lower clad layer.   The optical waveguide according to claim 1, wherein a light emitting diode or laser light is condensed by the first and second optical waveguides.   An optical information processing apparatus comprising: the optical waveguide according to claim 1; a light source that makes signal light incident on the optical waveguide; and a light receiving unit that receives outgoing light from the optical waveguide.   The optical information processing apparatus according to claim 12, wherein the optical information processing apparatus is configured as a display that projects the emitted light by scanning with a scanning unit.

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