JP4408083B2 - Optical multiplexing / demultiplexing device and optical circuit using the same - Google Patents

Description

  The present invention relates to an optical multiplexing / demultiplexing element that multiplexes light having different wavelengths and separates light having a predetermined wavelength from the multiplexed light, and an optical circuit using the same.

  In recent years, high-speed and large-capacity data transmission is required in information communication networks, and optical wavelength division multiplexing technology has been researched and developed. For example, in Patent Document 1 below, an optical combining device having a distributed Bragg reflector in a coupling region of an asymmetric directional coupler, which combines a stacked type and a horizontal type (arrangement of optical waveguides in a direction perpendicular to the stacking direction). A wave element is disclosed. In this optical multiplexing / demultiplexing element, since the effective refractive indexes of the two waveguides are different, the optical power can be exchanged between the two waveguides only at the operating wavelength of the distributed Bragg reflector.

  The following Patent Document 2 discloses an optical multiplexing / demultiplexing element in which two waveguides are three-dimensionally crossed in an X shape in order to improve the characteristics of the optical multiplexing / demultiplexing element disclosed in Patent Document 1. Patent Documents 3 and 4 listed below disclose an optical multiplexing / demultiplexing element integrated with a photodetector using the structure of Patent Document 1.

  Patent Document 5 listed below discloses an optical multiplexing / demultiplexing device having a distributed Bragg reflector in a coupling region of a horizontal directional coupler. In this optical multiplexing element, since the two waveguides have the same structure, optical power can be transferred between the waveguides in a wide wavelength range, and only the light having the operating wavelength of the distributed Bragg reflector is reflected. Output separately.

  Patent Document 6 below discloses an optical coupling element having a distributed Bragg reflector in a coupling region of a horizontal asymmetric directional coupler. In this optical multiplexing / demultiplexing element, since the effective refractive indexes of the two waveguides are different, the optical power can be exchanged between the waveguides only at the operating wavelength of the distributed Bragg reflector.

  Patent Document 7 below discloses an optical demultiplexing device having a distributed Bragg reflector in the coupling region of a horizontal Y-branch waveguide. In this optical multiplexing / demultiplexing element, only the operating wavelength of the distributed Bragg reflector is reflected.

  Non-Patent Document 1 below discloses an optical multiplexing / demultiplexing device having a distributed Bragg reflector inclined in the coupling region of a horizontal Y-branch waveguide. The arm portion of the Y branch waveguide is asymmetric, and the coupling portion is a two-mode waveguide. In this optical multiplexing / demultiplexing element, the multiplexed light propagating from the wider Y arm is coupled to the fundamental mode of the coupling section, and only the light of the operating wavelength is reflected and coupled to the primary mode of the coupling section by the distributed Bragg reflector. The reflected light is selectively coupled to the narrow side of the Y arm and propagates to separate the light. In addition, the multiplexing of light is performed by the reverse operation of the light separation.

Non-Patent Document 2 below discloses an optical filter that is realized on the same principle as Non-Patent Document 1 using an optical fiber.
Japanese Patent Laid-Open No. 9-218316 JP 2002-277653 A JP 2001-290039 A JP 2001-290180 A JP-A-11-52153 JP-A 63-163803 JP 2001-66560 A D. F. Geragty, et al. "Ion-exchanged waveguide add / drop filter", Electronics Letters, Vol. 37, PP. 829-831 (2001). A. S. Kewitsch, et al. "All-fiber zero-insertion-loss add-drop filter for wavelength-division multiplexing", Optics Letters, Vol. 23, PP. 106-108 (1998).

  However, in the directional coupler type optical multiplexing / demultiplexing elements of Patent Documents 1 to 6, it is difficult to increase the coupling coefficient, a long distance is required to obtain high conversion efficiency, and the wavelength selectivity is sharp. That is, there is a problem that the wavelength band that can be reflected is narrow.

  Further, the optical multiplexing / demultiplexing elements of Patent Documents 1 to 7 and Non-Patent Documents 1 and 2 include a horizontal structure, and require a relatively large space.

  Further, in Patent Document 7, since the waveguide is symmetrical, the output efficiency is only 25% at the maximum. Further, since light is reflected also on the input side, an isolator is required.

  In addition, in the optical multiplexing / demultiplexing device of Non-Patent Document 1 using a horizontal Y-branch structure, the distributed Bragg reflector must be inclined with respect to the waveguide, which is not easy to manufacture.

  In order to solve the above problems, an object of the present invention is to provide an optical multiplexing / demultiplexing device having a large coupling coefficient, high-density integration, a wide wavelength selection width, and an optical circuit using the same. It is in.

  The object of the present invention is achieved by the following means.

That is, the optical multiplexing / demultiplexing device (1) according to the present invention is laminated on the first core in such a way that the first core that propagates light and the light propagates and contacts only a predetermined region on the surface of the first core. the together with the first core, a second core cross section in the stacking direction to form a branching waveguide of Y-shaped branches in two directions at each of both ends of the predetermined region, the first core and the second core And a grating formed on a coupling portion formed in contact with the predetermined region, and the grating reflects light having an operating wavelength of the grating when a fundamental mode of the coupling portion is input. The first mode of the coupling unit is converted to the first mode. When the first mode of the coupling unit is input, the first mode is reflected and converted to the basic mode of the coupling unit .

  An optical multiplexing / demultiplexing element (2) according to the present invention includes a lower clad and a tapered portion whose thickness is gradually reduced to 0 in the optical multiplexing / demultiplexing element (1), and is provided on the lower clad. An upper clad formed excluding the predetermined region is further provided between the formed first core and the second core.

  An optical multiplexing / demultiplexing device (3) according to the present invention includes a lower clad having a flat portion and a convex portion including a tapered portion whose thickness gradually increases up to the flat portion in the optical multiplexing / demultiplexing device (1). An upper clad having a tapered portion whose thickness is gradually reduced to 0 and formed between the first core and the second core formed on the lower clad except for the predetermined region; Is further provided.

The optical multiplexing / demultiplexing element (4) according to the present invention further includes a first core layer and a second core layer in any of the optical multiplexing / demultiplexing elements (1) to (3), wherein the first core includes A thickness of the second core layer corresponding to the first predetermined portion, wherein the first core layer is a first predetermined portion formed thicker than a peripheral portion. Is a second predetermined portion formed thicker than the peripheral portion.

  The optical multiplexing / demultiplexing element (5) according to the present invention further includes a first core layer and a second core layer in any of the optical multiplexing / demultiplexing elements (1) to (3), wherein the first core includes The first core layer is a predetermined portion formed thicker than the peripheral portion, and the second core is disposed at a position corresponding to the predetermined portion, and the refractive index is positioned at the periphery. Different from the refractive index of the second core layer, or the refractive index of the first core is different from the refractive index of the first core layer located in the periphery, and the second core corresponds to the first core. The second core layer is a predetermined portion formed thicker than the peripheral portion.

  The optical multiplexing / demultiplexing element (6) according to the present invention further includes a first core layer and a second core layer in any of the optical multiplexing / demultiplexing elements (1) to (3), Unlike the refractive index of the first core layer located in the peripheral part, the second core is disposed at a position corresponding to the first core, and the refractive index of the second core layer located in the peripheral area. It is characterized by a different rate.

  The optical multiplexing / demultiplexing element (7) according to the present invention includes a periodic notch formed in the first core in any of the optical multiplexing / demultiplexing elements (1) to (6). And the material filling the notch, wherein the refractive index of the material is different from the refractive index of the first core and the refractive index of the second core.

  The optical multiplexing / demultiplexing element (8) according to the present invention includes a periodic notch formed in the first core in any of the optical multiplexing / demultiplexing elements (1) to (6). And the second core filling the notch.

  An optical multiplexing / demultiplexing element (9) according to the present invention includes any one of the optical multiplexing / demultiplexing elements (1) to (8), wherein the first core, the second core, the lower cladding, and the upper cladding are included. Each is characterized by being formed of glass or resin.

  The optical multiplexing / demultiplexing element (10) according to the present invention is the optical multiplexing / demultiplexing element (1) to (9), wherein a portion excluding the coupling portion of the first core and the second core is an optical coupling element. It is a single mode waveguide.

  In the optical multiplexing / demultiplexing element (11) according to the present invention, in any of the optical multiplexing / demultiplexing elements (1) to (10), input light wavelength-multiplexed from one end of the first core is input. Of the input light, only the light of the operating wavelength of the grating is reflected by the grating in the first mode of the coupling unit, and the light of the input light excluding the reflected light is the coupled light. The input light that has been wavelength-multiplexed by propagating through the coupling unit in the fundamental mode of the unit and propagating the reflected light in the fundamental mode of the second core in the second core other than the coupling unit To demultiplexing light having an operating wavelength of the grating.

Further, in the optical multiplexing / demultiplexing element (12) according to the present invention, in any of the optical multiplexing / demultiplexing elements (1) to (11), add light having an operating wavelength of the grating is input from one end of the second core. When input light is input from one end of the first core, the add light propagates in the fundamental mode in the second core other than the coupling portion, and propagates in the primary mode of the coupling portion in the coupling portion. Then, the input light is reflected by the grating in the fundamental mode of the coupling portion, and the reflected add light propagates in the fundamental mode of the first core in the first core other than the coupling portion. It is characterized by being multiplexed with light.

  Moreover, the optical multiplexing / demultiplexing element (13) according to the present invention is the optical multiplexing / demultiplexing element (1) to (12), wherein the coupling between the first core and the second core is effective. It is characterized by different refractive indexes.

  In the optical multiplexing / demultiplexing element (14) according to the present invention, in any of the optical multiplexing / demultiplexing elements (2) to (13), the refractive index of the first core is higher than the refractive index of the second core. The second core is characterized in that a refractive index of the second core is larger than any of the refractive indexes of the upper clad and the lower clad.

  Moreover, the optical multiplexing / demultiplexing element (15) according to the present invention has a vertical cross-sectional surface shape of the tapered portion whose thickness is gradually reduced to 0 in any of the optical multiplexing / demultiplexing elements (1) to (14). Is characterized by being linear, S-shaped with two arcs connected, or a cosine curve with a half cycle.

  An optical circuit (1) according to the present invention includes any one of the optical multiplexing / demultiplexing elements (1) to (15) and an optical input unit that inputs light from one end of the second core to the second core, or And a light receiving means for receiving light output from one end of the second core.

  In the optical circuit (2) according to the present invention, in the optical circuit (1), the optical input means includes a semiconductor laser, and light output from the semiconductor laser is transmitted from one end of the second core to the first optical circuit. A part of the second core and the upper clad is removed with a predetermined thickness so as to be incident on two cores, and the light input means is arranged in the optical multiplexing / demultiplexing element.

  In the optical circuit (3) according to the present invention, in the optical circuit (1), the optical input means includes a surface emitting semiconductor laser, and a part of the second core is removed to form a concave mirror. The light input means is disposed in the optical multiplexing / demultiplexing element so that light output from the surface emitting semiconductor laser is reflected by the concave mirror and enters the second core from one end of the second core. It is characterized by being.

  In the optical circuit (4) according to the present invention, in the optical circuit (1), the light input means includes a surface emitting semiconductor laser and a condenser lens, and a part of the second core is removed to obtain a flat mirror. And the light input means is configured to reflect the light output from the surface emitting semiconductor laser by the flat mirror and enter the second core from one end of the second core. It is characterized by being arranged in.

  The optical circuit (5) according to the present invention is characterized in that in any of the optical circuits (1) to (4), a plurality of the optical circuits are connected in series.

  According to the present invention, by adopting a laminated structure, a required space in the width direction can be narrowed, and an optical multiplexing / demultiplexing element integrated with higher density and an optical circuit using the same are realized. be able to.

  In addition, since the coupling coefficient can be increased, the propagation distance necessary for multiplexing and demultiplexing light can be shortened, and further high-density integration is possible.

  Further, since the coupling coefficient can be increased, a wide wavelength selection width can be realized, that is, the wavelength width that can be multiplexed and separated by one optical multiplexing / demultiplexing element can be increased.

  Further, since the size of the second core can be increased, the connection efficiency with external light is increased, and the light emitting means and the light receiving means can be mounted on the optical multiplexing / demultiplexing element with relatively low accuracy.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a longitudinal sectional view showing an optical multiplexing / demultiplexing device according to the first embodiment of the present invention. 2 is an example of a longitudinal sectional view of the optical multiplexing / demultiplexing device shown in FIG. 1, and (a) and (b) are sectional views taken along lines AA and BB in FIG. 1, respectively. It is.

  The present optical multiplexing / demultiplexing device is formed on a substrate 1, a lower cladding 2 formed on the substrate 1, a first core 3 formed on the lower cladding 2, and a part of the first core 3. And an upper clad 4 and a second core 5 formed on the upper clad 4 and the first core 3. Here, the thickness of the upper clad 4 is gradually reduced to 0 (hereinafter, this region is referred to as tapered portions 7a and 7b), and a part of the surface of the first core 3 is exposed. . Therefore, the second core 5 is formed on the upper clad 4 including the tapered portions 7 a and 7 b and on the exposed portion of the first core 3. Further, a grating 6 is formed at a portion where the first core 3 and the second core 5 are in contact with each other (hereinafter referred to as a coupling portion 8). As described above, the second core 5 is stacked on the first core 3 in contact with only a predetermined region (exposed portion) on the surface of the first core 3, and forms a Y-shaped structure together with the first core 3. Yes.

  The first core 3 and the second core 5 are made of a material that transmits light, such as glass and plastic, and the second core 5 is formed thicker than the first core 3. Further, as shown in FIGS. 2A and 2B, the first core 3 is formed such that the thickness of the predetermined portion of the first core layer 21 is thicker than the peripheral portion. The core 5 is formed by making the thickness of the predetermined portion corresponding to the first core 3 of the second core layer 22 thicker than the peripheral portion.

  The grating 6 is formed by removing the first core 3 over a predetermined length L at a predetermined interval ΔL (hereinafter referred to as a period) and a predetermined depth D, thereby forming periodic notches. The notches are filled with a material having a refractive index different from that of the first core 3 and the second core 5. Here, it is sufficient that the refractive index is changed with the notch as a boundary, and the notch may not be positively filled with a substance but may remain hollow (for example, air exists).

  Next, the function of the optical multiplexing / demultiplexing device according to the present embodiment shown in FIGS.

When the wavelength-multiplexed input light 9 (wavelength λ = λ1,..., Λm) is input to the first core 3, the operating wavelength λj of the grating 6, that is, the period ΔL of the grating 6, the fundamental mode of the coupling unit 8 Only the light having a specific wavelength λj determined by the effective refractive index N0 and the effective refractive index N1 for the first-order mode of the coupling unit 8 is reflected by the grating 6 and output as the drop light 12 through the second core 5. . On the other hand, light having a wavelength other than the wavelength λj passes through the grating 6 and is output as output light 10.

  Here, light propagates through the first core 3 in the first core layer 21 and through the second core 5 in the second core layer 22. In FIG. 1, among the modes of light propagating through the optical multiplexing / demultiplexing device, the fundamental mode 13 of the first core 3, the fundamental mode 14 of the second core 5, the fundamental mode 15 of the coupling unit 8, and 1 of the coupling unit 8 are illustrated. The next mode 16 is shown as a conceptual electromagnetic field distribution.

When the add light 11 having the wavelength λj is input to the second core 5, the light is reflected by the grating 6, multiplexed through the first core 3 and output to the output light 10. That is, the optical multiplexing / demultiplexing device shown in FIG. 1 can extract light having a predetermined wavelength λj from wavelength multiplexed light and multiplex light having the same wavelength λj input from the outside.

  Here, the AA sectional view and the BB sectional view in FIG. 1 are not limited to the sectional view shown in FIG. For example, the cross-sectional views shown in FIGS. 3 to 10 are examples of longitudinal sectional views of the optical multiplexing / demultiplexing device shown in FIG. 1, and (a) and (b) are taken along lines AA and BB in FIG. 1, respectively. It is sectional drawing.

  In the example shown in FIGS. 3 to 5, similarly to FIG. 2, the corresponding predetermined portions of the first core layer 21 and the second core layer 22 are made thicker than the peripheral portions, respectively, so that the first core 3 and the second core 2. A core 5 is formed. 2-5, the 1st core 3 and the 2nd core 5 are each formed by the convex shape in each one surface of the 1st core layer 21 and the 2nd core layer 22, and are shown to FIGS. The cross-sectional views correspond to four patterns corresponding to the arrangement of the surfaces on which the convex shapes are formed. That is, in the cross-sectional view shown in FIG. 2, the convex shapes of the first core layer 21 and the second core layer 22 are formed on the surface (upper side surface) in the same direction. In the cross-sectional view shown in FIG. 3, the convex shapes of the first core layer 21 and the second core layer 22 are formed on surfaces in opposite directions (surfaces that do not contact). In the cross-sectional view shown in FIG. 4, the convex shapes of the first core layer 21 and the second core layer 22 are formed on the same direction surface (lower side surface). In the cross-sectional view shown in FIG. 5, the convex shapes of the first core layer 21 and the second core layer 22 are formed on opposite surfaces (contact surfaces). 2 to 5 show a case where a convex shape is formed only on one surface of each of the first core layer 21 and the second core layer 22, and these are desirable because they are relatively easy to manufacture. However, the present invention is not limited to these, and convex shapes may be formed on both surfaces of each of the first core layer 21 and the second core layer 22 as long as a region where light propagates can be defined.

  In the example shown in FIGS. 6 to 9, a convex shape is formed on one of the first core layer 21 and the second core layer 22, and a substance having a different refractive index is used without forming a convex shape on the other. The first core 3 or the second core 5 is formed. In the cross-sectional views shown in FIGS. 6 and 7, the first core 3 is made of a material (glass, resin, etc.) having a refractive index different from that of the first core layer 21, and the surface of the first core layer 21 and the first core are formed. No step is formed with respect to the surface of 3, and the second core layer 22 has a convex shape. 6 and 7, the surface of the second core layer 22 on which the convex shape is formed is different. 8 and 9, the first core layer 21 has a convex shape, and the second core 5 is made of a material (glass, resin, etc.) having a different refractive index of light from the second core layer 22. The step is formed, and no step is formed between the surface of the second core layer 22 and the surface of the second core 5. 8 and 9, the surface of the first core layer 21 on which the convex shape is formed is different. In the cross-sectional views shown in FIGS. 6 to 9, convex shapes may be formed on both surfaces of the first core layer 21 or the second core layer 22 to form the first core 3 or the second core 5. 6 to 9, when the first core 3 or the second core 5 is formed using a material having a refractive index different from that of the first core layer 21 or the second core layer 22, As long as the propagation region can be defined, there may be a step between the surface of the first core layer 21 and the surface of the first core 3, and a step between the surface of the second core layer 22 and the surface of the second core 5. There may be.

  In the example shown in FIG. 10, the first core 3 is formed of a material (glass, resin, or the like) having a light refractive index different from that of the first core layer 21, and the surface of the first core layer 21 and the first core 3 are formed. The second core 5 is made of a material having a refractive index of light different from that of the second core layer 22 (such as glass or resin), and the surface of the second core layer 22 and the second core 5 are not formed. No step is formed with the surface of the core 5. Here, there may be a step between the surface of the first core layer 21 and the surface of the first core 3 as long as the region where light propagates can be defined, and the surface of the second core layer 22 and the second core 5. There may be a step on the surface of the surface.

(Second Embodiment)
FIG. 11 is a longitudinal sectional view showing an optical multiplexing / demultiplexing device according to the second embodiment of the present invention. FIG.
The configuration of the optical multiplexing / demultiplexing device shown in FIG. 1 is the same as that shown in FIG. 1 except for the grating 6a.

  In FIG. 11, in the grating 6a, a part of the first core is removed at a predetermined period in the coupling portion 8 to form a notch, and the first core 3 is in close contact therewith, that is, the first core. The second core 5 is formed by filling the portion from which 3 is removed. Therefore, the optical multiplexing / demultiplexing element shown in FIG. 11 separates light of a predetermined wavelength from wavelength-multiplexed light as in the optical multiplexing / demultiplexing element shown in FIG. Can be multiplexed.

  The cross-sectional view along the line C-C and the cross-sectional view along the line D-D in FIG. 11 may be any of the cross-sectional views in FIGS. 2 to 10 as in the first embodiment.

(Third embodiment)
FIG. 12 is a longitudinal sectional view showing an optical multiplexing / demultiplexing device according to the third embodiment of the present invention. The configuration of the optical multiplexing / demultiplexing device shown in FIG. 12 is the same as that shown in FIG. 1 except for the lower cladding 2a, the first core 3a, the upper cladding 4a, the second core 5a, and the tapered portions 7c and 7d. Are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 12, the lower clad 2a has a convex portion whose thickness gradually increases from a predetermined thickness, maintains a constant thickness, and thereafter the thickness gradually decreases. The region where the thickness of the lower clad 2a changes gently is called the taper portions 7c and 7d, and the region maintaining a certain thickness sandwiched between them is called the flat portion. The first core 3a is formed on the lower clad 2a having a convex portion. Except for the first core 3a on the flat part of the lower clad 2a, the upper clad 4a is formed on the first core 3a at the same height as the surface of the first core 3a on the flat part without causing a step. Is formed. Further, the second core 5a is formed on the first core 3a and the upper clad 4a. A grating 6 is formed in a portion (joint portion 8) where the first core 3a and the second core 5a are in direct contact with each other as in the first embodiment.

  Accordingly, the optical multiplexing / demultiplexing element shown in FIG. 12 takes out light of a predetermined wavelength from the wavelength multiplexed light as in the optical multiplexing / demultiplexing elements shown in FIGS. Can be multiplexed.

  The cross-sectional view taken along the line EE and the cross-sectional view taken along the line FF in FIG. 12 are the cross-sectional views of FIGS. 2 to 10 as in the first and second embodiments. May be.

(Fourth embodiment)
FIG. 13 is a longitudinal sectional view showing an optical multiplexing / demultiplexing device according to the fourth embodiment of the present invention. Since the configuration of the optical multiplexing / demultiplexing device shown in FIG. 13 is the same as that of FIG. 12 except for the grating 6a, the same components are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 13, as in the first embodiment, the grating 6a has a notch formed by removing a part of the first core 3a at a predetermined period in the coupling portion 8, and on the first core. The second core 5a is formed in close contact with 3a, that is, by filling the portion from which the first core 3a has been removed. Therefore, the optical multiplexing / demultiplexing element shown in FIG. 13 takes out light of a predetermined wavelength from the wavelength multiplexed light, and has a predetermined wavelength inputted from the outside, like the optical multiplexing / demultiplexing elements shown in FIGS. Light can be multiplexed.

  Note that the cross-sectional view taken along the line GG and the cross-sectional view taken along the line H-H in FIG. 13 are the cross-sectional views shown in FIGS. 2 to 10 as in the first to third embodiments. May be.

As described above, in the optical multiplexing / demultiplexing elements according to the first to fourth embodiments, the case where the tapered portion of the upper cladding or the lower cladding is formed in a straight line has been described, but the present invention is not limited thereto, and is formed thereon. As long as the first core or the second core has a shape that smoothly changes, for example, an S-shape formed by connecting two arcs so that the tangent lines coincide at the connection portion ((a) in FIG. 14). ), A cosine curve shape corresponding to a half cycle ((b) of FIG. 14) may be used. In FIG. 14A, the centers of the two arcs are indicated by points O ₁ and O ₂ .

  Moreover, although the case where the lower clad was provided on the board | substrate was demonstrated above, you may form a board | substrate and a lower clad integrally. For example, in the case of the third and fourth embodiments shown in FIGS. 12 and 13, the lower cladding 2a is eliminated, the substrate is formed with a convex portion like the lower cladding, and the first core is formed thereon. May be formed.

(Fifth embodiment)
15 to 17 are longitudinal sectional views showing optical circuits according to the fifth embodiment of the present invention. The optical circuit according to the present embodiment includes an optical multiplexing / demultiplexing element (see FIGS. 1, 11, 12, and 13) according to any one of the first to fourth embodiments according to the present invention, and an optical input unit. I have. 15 to 17 show different light input means and an optical multiplexing / demultiplexing element in which a light input portion is processed according to the light input means.

  FIG. 15 shows a case where the light input means is a semiconductor laser 31 including a semiconductor laser core 32. As shown in FIG. 15, the second core 5 and a part of the upper clad 4 have a predetermined thickness so that light output from the semiconductor laser core 32 enters the second core 5 from one end of the second core 5. The semiconductor laser 31 is fixed to the optical multiplexing / demultiplexing device using the bonding portion 33. The light output from the semiconductor laser core 32 enters the second core 5 and is multiplexed by the optical multiplexing / demultiplexing element as described above.

  FIG. 16 shows a case where the light input means is a surface emitting semiconductor laser 34 provided with a light emitting unit 35. As shown in FIG. 16, a part of the second core 5 is removed to form a concave mirror 36 so that the light output from the light emitting portion 35 enters from one end of the second core 5. The laser 34 is disposed above the optical multiplexing / demultiplexing element. The light output from the light emitting unit 35 is reflected by the concave mirror 36, enters the second core 5, and is multiplexed by the optical multiplexing / demultiplexing element as described above.

  FIG. 17 shows a case where the light input means includes a surface emitting semiconductor laser 34 having a light emitting unit 35 and a condenser lens 38. As shown in FIG. 17, a condensing lens 38 is attached to the surface emitting semiconductor laser 34, a part of the second core 5 is removed to form a plane mirror 37, and light output from the light emitting unit 35 is second. The surface emitting semiconductor laser 34 is disposed above the optical multiplexing / demultiplexing element so as to enter the core 5. The light output from the light emitting unit 35 is collected by the condenser lens 38, reflected by the plane mirror 37, incident on the second core 5, and combined by the optical multiplexing / demultiplexing element as described above.

  Although the case where a laser is used as the light emitting means has been described above, the present invention is not limited to this, and a light emitting element used in an optical transmission technology such as an LED can be used.

In the above description, an optical circuit including one optical multiplexing / demultiplexing element and one optical input unit according to any one of the first to fourth embodiments according to the present invention has been described. It is also possible to configure an optical multiplexing circuit that combines a plurality of optical circuits shown in FIG. That is, as shown in FIG. 18, the first optical circuit according to the present invention including a grating capable of reflecting the wavelength λ1 and the second optical circuit according to the present invention including a grating capable of reflecting λ2. These optical circuits can also be connected by bringing the first cores and the second cores into contact with each other. As a result, it is possible to output light in which the wavelength λ1 output from the light input means 31a and the light having the wavelength λ2 (λ2 ≠ λ1) output from the light input means 31b are multiplexed.

  Further, the optical circuit including the optical input unit has been described above. However, the optical circuit includes the optical multiplexing / demultiplexing element and the light receiving element according to any one of the first to fourth embodiments according to the present invention. Can be formed. In addition, if a light separation circuit is formed by providing a plurality of optical circuits each including the optical multiplexing / demultiplexing element and the light receiving element according to the present embodiment, it is possible to separate light having different wavelengths from multiplexed light having a plurality of wavelengths.

  A plurality of optical multiplexing circuits described above can be used as an optical multiplexing system by providing an optical multiplexing circuit on the transmission side and an optical separation circuit on the receiving side, and connecting them via an optical transmission line using an optical fiber or the like. it can.

  The optical multiplexing / demultiplexing elements shown in the first to fifth embodiments can be formed using a known semiconductor process. In particular, for the taper portion, for example, a method in which the lower clad is formed by a shadow deposition method using a shadow mask, a photoresist applied on the lower clad layer is used, and a gray mask (a mask having a distribution of light transmittance) is used. For example, a dry etching method after exposure and an electron beam resist coated on the lower clad may be formed by controlling the dose amount and performing a dry etching after exposure.

  Examples are shown below to further clarify the features of the present invention.

  In the optical multiplexing / demultiplexing device according to the first embodiment shown in FIG. 1, the refractive index of the lower cladding 2 is 1.46, the refractive index of the first core 3 is 1.54, the thickness thereof is 0.83 μm, The refractive index of the upper cladding 4 is 1.46, the thickness is 5 μm, the refractive index of the second core 5 is 1.47, the thickness is 4 μm, the period ΔL of the grating 6 is 0.285 μm, and the total length L is 300 μm. The refractive index of the notch forming the grating 6, that is, the material filled in the notch formed by removing a part of the first core 3 is 2.0, and the depth D of the notch is 0.03 μm. When the length of each of the taper portions 7a and 7b of the lower clad 2 is about 240 μm and the longitudinal cross-sectional shape of the taper portions 7a and 7b is formed in an S shape, an input with a wavelength of 0.85 μm is input to this optical multiplexing / demultiplexing device Light 9 is dropped into light 12 with 98% efficiency It is taken out. Further, the add light 11 having a wavelength of 0.85 μm to the optical multiplexing / demultiplexing element is extracted as output light 10 with an efficiency of 98%. In this case, the allowable wavelength range is 0.002 μm, and the input light 9 having a wavelength outside this range is extracted as output light 10 with an efficiency of 99% or more without being substantially affected by the grating 6. That is, it can be seen that the wavelength selectivity for light of a specific wavelength (0.85 μm) of this optical multiplexing / demultiplexing element is very high, and the transmittance for light of other wavelengths is very high.

In the optical multiplexing / demultiplexing device according to the third embodiment shown in FIG. 12, the refractive index of the lower cladding 2a is 1.46, the refractive index of the first core 3a is 1.54, its thickness is 0.83 μm, The refractive index of the upper cladding 5a is 1.46, its thickness is 5 μm, the refractive index of the second core 3a is 1.47, its thickness is 4 μm, the period ΔL of the grating 6 is 0.285 μm, and its total length L is 300 μm. The refractive index of the material filled in the notch forming the grating 6 is 2.0, the depth D of the notch is 0.03 μm, and the length of each of the tapered portions 7c and 7d of the lower cladding is about 190 μm, When the longitudinal cross-sectional shape of the taper portions 7c and 7d is formed in an S-shape, the input light 9 having a wavelength of 0.85 μm to the optical multiplexing / demultiplexing element is extracted as drop light 12 with an efficiency of 98%. Further, the add light 11 having a wavelength of 0.85 μm to the optical multiplexing / demultiplexing element is extracted as output light 10 with an efficiency of 98%. In this case, the allowable wavelength range is 0.002 μm, and the input light 9 having a wavelength outside this range is extracted as output light 10 with an efficiency of 98% or more. That is, as in Example 1, it can be seen that the selectivity of the optical multiplexing / demultiplexing element with respect to light of a specific wavelength (0.85 μm) is very high and the transmittance with respect to light of other wavelengths is very high.

1 is a longitudinal sectional view showing an optical multiplexing / demultiplexing device according to a first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is an example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) is sectional drawing along the AA line and BB line of FIG. 1, respectively. It is. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is another example of the longitudinal cross-sectional view of the optical multiplexing / demultiplexing element which concerns on the 1st Embodiment of this invention, (a), (b) was along the AA line and BB line of FIG. 1, respectively. It is sectional drawing. It is a longitudinal cross-sectional view which shows the optical multiplexing / demultiplexing element which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the optical multiplexing / demultiplexing element which concerns on the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the optical multiplexing / demultiplexing element which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows the example of the taper part of the optical multiplexing / demultiplexing element which concerns on embodiment of this invention, (a) is S shape which consists of two circular arcs, (b) is a taper part formed in the cosine curve. Show. It is a longitudinal cross-sectional view which shows an example of the optical circuit which concerns on the 5th Embodiment of this invention. It is a longitudinal cross-sectional view which shows another example of the optical circuit which concerns on the 5th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the example according to the optical circuit which concerns on the 5th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the state which connected the optical circuit of this invention in series.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2, 2a Lower clad 3, 3a 1st core 4, 4a Upper clad 5, 5a 2nd core 6, 6a Grating 7a, 7b, 7c, 7d Tapered part 8 Coupling part 9 Input light 10 Output light 11 Add light 12 Dropped light 13 First core fundamental mode 14 Second core fundamental mode 15 Coupling unit fundamental mode 16 Coupling unit primary mode 21 First core layer 22 Second core layers 31, 31a, 31b Semiconductor laser 32 Semiconductor laser core 33 Bonding part 34 Surface emitting semiconductor laser 35 Light emitting part 36 Concave mirror 37 Plane mirror 38 Condensing lens

Claims (20)

A first core that propagates light;
The light propagates and contacts only a predetermined region of the surface of the first core and is stacked on the first core. Along with the first core , the cross-sectional shape in the stacking direction is two directions at each end of the predetermined region. and the second core to form a Y-shaped branch waveguide branched,
A grating formed on a coupling portion formed by the first core and the second core being in contact with each other in the predetermined region;
When the fundamental mode of the coupling unit is input to the light having the operating wavelength of the grating , the grating reflects and converts the light into the primary mode of the coupling unit, and the primary mode of the coupling unit is input. In this case, the optical multiplexing / demultiplexing element has a function of reflecting and converting to the fundamental mode of the coupling portion .
A lower cladding,
An upper clad formed between the first core and the second core formed on the lower clad, excluding the predetermined region, and having a tapered portion whose thickness gradually decreases to 0; The optical multiplexing / demultiplexing device according to claim 1, further comprising: A lower clad having a flat portion and a convex portion comprising a tapered portion whose thickness gradually increases to the flat portion;
An upper clad formed between the first core and the second core formed on the lower clad, excluding the predetermined region, and having a tapered portion whose thickness gradually decreases to 0; The optical multiplexing / demultiplexing device according to claim 1, further comprising: A first core layer and a second core layer;
The first core is a first predetermined portion formed such that the thickness of the first core layer is thicker than the peripheral portion;
The said 2nd core is a 2nd predetermined part by which the thickness of the said 2nd core layer corresponding to the said 1st predetermined part was formed more thickly than the periphery part. The optical multiplexing / demultiplexing device according to any one of the above. A first core layer and a second core layer;
The first core is a predetermined portion in which the thickness of the first core layer is thicker than the peripheral portion, and the second core is disposed at a position corresponding to the predetermined portion, and the refractive index is Different from the refractive index of the second core layer located in the periphery, or
The refractive index of the first core is different from the refractive index of the first core layer located in the peripheral portion, the second core corresponds to the first core, and the thickness of the second core layer is larger than that of the peripheral portion. The optical multiplexing / demultiplexing device according to claim 1, wherein the optical multiplexing / demultiplexing device is a predetermined portion formed to be thick. A first core layer and a second core layer;
The refractive index of the first core is different from the refractive index of the first core layer located in the periphery,
The said 2nd core is arrange | positioned in the position corresponding to a said 1st core, and the refractive index differs from the refractive index of the said 2nd core layer located in the periphery. The optical multiplexing / demultiplexing device according to 1. The grating is formed by a periodic cutout formed in the first core and a material filling the cutout;
The optical multiplexing / demultiplexing device according to claim 1, wherein a refractive index of the substance is different from a refractive index of the first core and a refractive index of the second core. The grating is
A periodic notch formed in the first core;
2. The second core that fills the notch and is formed by the second core.
The optical multiplexing / demultiplexing device according to any one of -6.   The optical multiplexing / demultiplexing according to any one of claims 1 to 8, wherein each of the first core, the second core, the lower clad, and the upper clad is formed of glass or resin. element.   10. The optical multiplexing / demultiplexing device according to claim 1, wherein a portion excluding the coupling portion of the first core and the second core is a single mode waveguide of light. . When input light wavelength-multiplexed from one end of the first core is input,
Of the input light, only the light of the operating wavelength of the grating is reflected by the grating in the first mode of the coupling unit,
Of the input light, light excluding the reflected light propagates in the coupling unit in the fundamental mode of the coupling unit,
The reflected light propagates in the fundamental mode of the second core in the second core other than the coupling unit, thereby demultiplexing the light having the operating wavelength of the grating from the wavelength-multiplexed input light. The optical multiplexing / demultiplexing device according to claim 1, wherein the optical multiplexing / demultiplexing device is according to claim 1. When the add light of the operating wavelength of the grating is input from one end of the second core and the input light is input from one end of the first core,
The add light propagates in the fundamental mode in the second core other than the coupling part, propagates in the first mode of the coupling part in the coupling part, and is reflected in the fundamental mode of the coupling part by the grating,
12. The reflected add light is multiplexed with the input light by propagating in the fundamental mode of the first core in the first core other than the coupling unit. The optical multiplexing / demultiplexing device according to any one of the above.   The optical multiplexing / demultiplexing device according to claim 1, wherein the effective refractive index of the first core and the second core is different except for the coupling portion. The refractive index of the first core is greater than the refractive index of the second core;
14. The optical multiplexing / demultiplexing device according to claim 2, wherein a refractive index of the second core is larger than any of the refractive indexes of the upper cladding and the lower cladding.   2. The surface shape of the longitudinal section of the tapered portion whose thickness gradually decreases to 0 is a linear shape, an S-shape with two arcs connected, or a half-period cosine curve shape. The optical multiplexing / demultiplexing device according to any one of -14. The optical multiplexing / demultiplexing device according to any one of claims 1 to 15,
An optical circuit comprising: light input means for inputting light to the second core from one end of the second core; or light receiving means for receiving light output from one end of the second core. The light input means comprises a semiconductor laser;
A part of the second core and the upper clad are removed at a predetermined thickness so that light output from the semiconductor laser is incident on the second core from one end of the second core, and the light The optical circuit according to claim 16, wherein an input unit is disposed in the optical multiplexing / demultiplexing element. The light input means comprises a surface emitting semiconductor laser;
A concave mirror is formed by removing a portion of the second core;
The light input means is disposed in the optical multiplexing / demultiplexing element so that light output from the surface emitting semiconductor laser is reflected by the concave mirror and enters the second core from one end of the second core. The optical circuit according to claim 16. The light input means comprises a surface emitting semiconductor laser and a condenser lens;
A portion of the second core is removed to form a plane mirror;
The light input means is disposed in the optical multiplexing / demultiplexing element so that light output from the surface emitting semiconductor laser is reflected by the planar mirror and enters the second core from one end of the second core. The optical circuit according to claim 16.   The optical circuit according to any one of claims 16 to 19, wherein a plurality of the optical circuits are connected in series.

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