JP5867336B2 - Optical transceiver and optical transmission system - Google Patents

Description

The present invention relates to an optical transceiver device and an optical transmission system.

  As the amount of information transmitted increases, optical transmission using optical fibers capable of high-speed and large-capacity transmission has become mainstream. Among them, in order to further improve the signal density, a multi-core optical fiber having a plurality of cores in one fiber has been developed, and is considered to become the mainstream of information transmission in the future.

  On the other hand, in order to reduce the height, a planar light emitting element array having M columns × N rows of light emitting elements in a plane, a multistage optical waveguide array having M columns × N stages of cores, and M of the multistage optical waveguide array An optical waveguide connection structure including M × N mirrors provided at positions corresponding to light emitting elements of columns × N rows has been proposed (for example, see Patent Document 1).

JP 2007-212687 A

An object of the present invention is an optical transmission / reception in which an optical signal optically couples an optical element and a core without passing through the other core in a configuration using an optical transmission line in which a plurality of cores are arranged in a hierarchy. to provide an apparatus and an optical transmission system.

  As one aspect of the present invention, the following optical transceiver, optical transmission system, and multicore optical fiber are provided.

[ 1 ] A light input / output surface having a plurality of light input / output sections for inputting or outputting a plurality of light signals, a surface-type optical element having a mounting surface opposite to the light input / output surface, and the plurality of lights A multi-core optical fiber having a plurality of cores arranged in a concentric circle symmetrically with respect to at least one symmetry axis on a transverse section, and optically coupled individually via an input / output unit and a reflecting surface formed at one end The plurality of cores are arranged with the axis of symmetry inclined with respect to the light input / output plane so that an optical path connecting the light input / output unit and the corresponding core does not pass through the other cores. Optical transceiver.
[ 2 ] The optical transceiver according to [1 ], wherein the optical element is a surface emitting semiconductor laser.

[ 3 ] A light output surface having a plurality of light output portions for outputting a plurality of light signals, a surface-type light emitting element having a mounting surface opposite to the light output surface, and a plurality of light signals for inputting a plurality of light signals. A light input surface having a light input portion; a surface-type light receiving element having a mounting surface opposite to the light input surface; a plurality of light output portions; a reflective surface formed at one end; and the plurality of light input portions. And a multi-core optical fiber having a plurality of cores that are optically coupled individually via a reflecting surface formed at the other end and arranged concentrically with respect to at least one symmetry axis on the transverse section , The plurality of cores are arranged with respect to the light output surface and the light input surface so that respective light paths connecting the light output unit and the light input unit and the corresponding cores do not pass through the other cores. An optical transmission system arranged with the axis of symmetry tilted .

[6] A plurality of cores that are symmetrically and concentrically arranged with respect to at least one axis of symmetry on the transverse plane and that transmit optical signals, and are formed around the plurality of cores, and have a refractive index that is greater than the refractive index of the cores A multi-core optical fiber comprising: a clad having a low refractive index; and a reflecting surface that is inclined with respect to an axis crossing the symmetry axis and reflects the optical signal.

According to the first and third aspects of the invention, in the configuration using the optical transmission path in which a plurality of cores are arranged in a hierarchy, the optical element and the core are optically coupled without passing through other cores. can do.
According to the second aspect of the present invention, it is possible to increase the density of the light input / output unit as compared with other types of light emitting elements.

FIG. 1 is a front view showing a schematic configuration example of an optical transmission system according to the first embodiment of the present invention. FIG. 2 is a view in the direction of arrow A in FIG. FIG. 3 is a plan view of the surface emitting semiconductor laser. 4 is a cross-sectional view taken along line BB in FIG. FIG. 5 is a view in the direction of arrow C in FIG. FIG. 6 is a plan view of the light receiving element. FIG. 7 is a diagram illustrating a configuration example of a transmission apparatus according to the second embodiment of the present invention. FIG. 8 shows a configuration example of a transmission apparatus according to the third embodiment of the present invention, where (a) is a front view, (b) is a view in the direction of arrow D in (a), and (c) is FIG. 9A and 9B show an embodiment, in which FIG. 9A is a cross-sectional view of a multicore optical fiber when cores are arranged at the center and apex of a regular hexagon, and FIG. 9B is a rotation angle from the vertical axis of the symmetry axis of the multicore optical fiber. The figure which shows the relationship between (theta) and the horizontal position (position information X) of the core centers P1-P7, (c) is a figure which shows the rotation angle (theta) and the distance between core centers.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the component which has the substantially same function, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

[First Embodiment]
FIG. 1 is a front view showing a schematic configuration example of an optical transmission system according to the first embodiment of the present invention. FIG. 2 is a view in the direction of arrow A in FIG. FIG. 3 is a plan view of the surface emitting semiconductor laser, and FIG. 4 is a cross-sectional view taken along the line BB of FIG. 5 is a view in the direction of the arrow C in FIG. 1, and FIG. 6 is a plan view of the light receiving element.

  As illustrated in FIG. 1, the optical transmission system 1 includes a transmission device 2 that transmits a plurality of optical signals, a multicore optical fiber 3 that transmits a plurality of optical signals transmitted from the transmission device 2, and a multicore optical fiber 3. And a receiving device 4 for receiving a plurality of optical signals transmitted by. Here, each of the transmission device 2 and the reception device 4 is an example of an optical transmission / reception device. The multi-core optical fiber 3 is an example of an optical transmission path. The optical transmission line may be an optical waveguide.

  The transmitter 2 includes a surface emitting semiconductor laser 20, a support member 21 that supports the end of the optical signal incident side of the multi-core optical fiber 3, a surface emitting semiconductor laser 20, a supporting member 21, and a surface emitting semiconductor. And a circuit board 22 on which a drive circuit (not shown) for driving the laser 20 is mounted. The surface emitting semiconductor laser 20 is an example of a surface type optical element. The support member 21 has a curved receiving surface 21 a that receives the circumferential surface of the multi-core optical fiber 3.

  The receiving device 4 amplifies the output signals of the light receiving element 40, the support member 41 that supports the optical signal emitting end of the multi-core optical fiber 3, and the light receiving element 40, the support member 41, and the light receiving element 40. And a circuit board 42 on which a non-amplifying circuit is mounted. The light receiving element 40 is an example of a surface type optical element. The support member 41 has a curved receiving surface 41 a that receives the circumferential surface of the multi-core optical fiber 3.

(Multi-core optical fiber)
As shown in FIG. 2, the multi-core optical fiber 3 has a plurality of cores 30 a to 30 g (also collectively referred to as core 30) hierarchically with respect to the light output surface 20 a of the surface emitting semiconductor laser 20. Has been placed. Specifically, the multi-core optical fiber 3 includes a core 30a disposed on the central axis 3a, and a plurality of (for example, six) cores 30b to 30g disposed at equal intervals on a concentric circle with respect to the central axis 3a. The clad 31 is formed around the cores 30a to 30g and has a refractive index lower than that of the cores 30a to 30g. Further, as shown in FIG. 1, the multi-core optical fiber 3 has reflection surfaces 32a and 32b inclined at 45 ° with respect to the central axis 3a at both ends. In FIG. 1, only three cores 30a, 30d, and 30g are shown.

  As shown in FIGS. 1 and 2, the plurality of cores 30 a to 30 g of the multi-core optical fiber 3 include a plurality of light emitting units 210 a to 210 g (which will be described later) of the surface emitting semiconductor laser 20 through one reflecting surface 32 a (which are described below). When collectively referred to as the light-emitting portion 210), they are individually optically coupled. Similarly, as shown in FIGS. 1 and 5, the plurality of cores 30a to 30g are provided with a plurality of light receiving portions 410a to 410g (to be described later) of the light receiving element 40 through the other reflecting surface 32b. Is also referred to as a light receiving portion 410). In the present embodiment, the distance between adjacent light emitting sections 210 in FIG. 2 is set to be equal, and the distance between adjacent light receiving sections 410 in FIG. 5 is also set to be equal.

  As shown in FIGS. 2 and 5, the plurality of cores 30 of the multi-core optical fiber 3 include optical paths (optical axes) 23 and 43 connecting the light emitting unit 210 and the light receiving unit 410 and the corresponding core 30, as other cores. 30 so as not to pass through. That is, the plurality of cores 30 are arranged symmetrically and concentrically with respect to at least one symmetry axis 3b on the cross section, and the light output surface 20a of the surface emitting semiconductor laser 20 or the light input surface described later of the light receiving element 40. The symmetry axis 3b is arranged with a predetermined angle θ (for example, 10 ° to 12 °) inclined with respect to the vertical axis 3c perpendicular to 40a. As shown in FIGS. 2 and 5, the vertical axis 3c intersects the symmetry axis 3b, and the reflecting surfaces 32a and 32b are inclined 45 ° with respect to the vertical axis 3c as shown in FIG.

  The multi-core optical fiber 3 includes a silica glass-based optical fiber in which the core 30 and the clad 31 are made of quartz glass, a polymer clad optical fiber in which the core 30 is made of quartz glass, and the clad 31 is made of plastic, the core 30 and the clad A plastic optical fiber 31 formed of plastic can be used. The multicore optical fiber 3 may be a single mode optical fiber or a multimode optical fiber. A protective layer may be provided on the outer periphery of the clad 31.

(Surface emitting semiconductor laser)
The surface emitting semiconductor laser 20 is a surface light emitting element having a light output surface 20a for outputting an optical signal and a mounting surface 20b on the opposite side of the light output surface 20a. For example, as shown in FIGS. In addition, a substrate 200 made of n-type GaAs, a light emitting unit 210a by a mesa unit arranged at the center of the substrate 200, and a plurality of (for example, six) mesa units arranged concentrically with respect to the center of the substrate 200. Light emitting units 210b to 210g. As the surface emitting semiconductor laser 20, a light emitting element that emits single mode or multimode laser light can be used. Here, the light output surface 20a is an example of a light input / output surface. The light emitting unit 210 is an example of a light input / output unit or a light output unit.

  As shown in FIG. 3, the surface emitting semiconductor laser 20 has a p-side electrode 215 having an opening 215 a formed on the light output surface side of the light emitting portions 210 a to 210 g, and wiring patterns 216 </ b> A and 216 </ b> B are formed from the p-side electrode 215. A conductive pattern is formed so as to reach the electrode pad 217. The opening 215a serves as an exit from which the optical signal exits.

As shown in FIG. 4, the light emitting unit 210 (210 a to 210 _{g) includes} an n-type lower DBR layer 211 made of an Al _x Ga _(1-x) As multilayer film, an active layer 212 made of MQW, an aperture on a substrate 200. A current confinement layer 213 having 213a, a p-type upper DBR layer 214 made of an Al _x Ga _(1-x) As multilayer film, and a p-side electrode 215 having an opening 215a are formed in this order. In the surface emitting semiconductor laser 20, an n-side electrode 230 is formed on the lower surface of the substrate 200. The electrode pad 217 and the n-side electrode 230 are connected to the drive circuit on the circuit board 22 through the wiring pattern of the support member 21.

(Light receiving element)
The light receiving element 40 is a surface type light receiving element having a light input surface 40a for inputting an optical signal and a mounting surface 40b on the opposite side of the light input surface 40a. For example, a photodiode or the like can be used. As shown in FIGS. 1, 5, and 6, the light receiving element 40 includes a substrate 400, a light receiving unit 410 a disposed at the center of the substrate 400, and a plurality of concentric circles disposed with respect to the center of the substrate 400. (For example, six) light receiving units 410b to 410g. In this embodiment, the light receiving units 410a to 410g use GaAs PIN photodiodes having excellent high-speed response. The PIN photodiode includes, for example, a P-layer, an I-layer and an N-layer that are PIN-bonded on a substrate 400 made of GaAs, a p-side electrode 411 connected to the P-layer, and an n-side formed on the N-layer. An electrode 414. The light input surface 40a is an example of a light input / output surface. The light receiving unit 410 is an example of a light input / output unit or a light input unit.

  As shown in FIG. 6, a p-side electrode 411 having an opening 411a is formed in the light receiving unit 410, and a conductive pattern is formed from the p-side electrode 411 to the electrode pad 413 through the wiring patterns 412A and 412B. Has been. In the light receiving portion 410, an n-side electrode 414 is formed so as to surround the p-side electrode 411, and a conductive pattern is formed from the n-side electrode 414 to the electrode pad 416 through the wiring patterns 415A and 415B. ing. The opening 411a serves as an entrance through which an optical signal enters. The electrode pads 413 and 416 are connected to the amplifier circuit on the circuit board 42 through the wiring pattern of the support member 41.

(Operation of the first embodiment)
In the first embodiment, the drive circuit of the transmission device 2 drives each light emitting unit 210 of the surface emitting semiconductor laser 20 to output an optical signal. The optical signal output from each light emitting unit 210 of the surface emitting semiconductor laser 20 enters the corresponding core 30 through the reflecting surface 32a without passing through the other cores 30 of the multi-core optical fiber 3. Each optical signal incident on the core 30 is transmitted to the other end side by the core 30, reflected by the reflecting surface 32b, and then received by the light receiving unit 410 of the corresponding light receiving element 40 without passing through the other core 30. . The light receiving unit 410 that has received the optical signal outputs an electrical signal corresponding to the amount of the optical signal to the amplifier circuit. The amplifier circuit amplifies the electrical signal output from the light receiving unit 410.

(Effects of the first embodiment)
According to the first embodiment, the following effects are obtained.
(A) In a configuration in which an optical signal is transmitted through another core and incident on the corresponding core, refraction and reflection occur due to a difference in refractive index between the other core and the clad, which becomes transmission loss and coupling loss. In addition, a part of the optical signal is incident on the other core, which causes generation of crosstalk (noise). According to the first embodiment, by tilting the symmetry axis 3b of the multi-core optical fiber 3 with respect to the vertical axis 3c, the light signal of the surface-emitting type semiconductor laser 20 can be transmitted without passing through the other cores 30. 210 and the light receiving portion 410 of the light receiving element 40 and the core 30 can be optically coupled.
(B) By using a planar light emitting element and a planar light receiving element, the transmission device 2 and the receiving device 4 can be reduced in height.
(C) Since the core 30 and the optical element are optically coupled via the reflecting surfaces 32a and 32b of the multi-core optical fiber 3, optical members such as prisms and lenses can be omitted. In addition, you may use an optical member as needed.

[Second Embodiment]
FIG. 7 is a diagram illustrating a configuration example of a transmission apparatus according to the second embodiment of the present invention. The transmission apparatus 2 of the optical transmission system according to the present embodiment includes a reflection film 33 formed on the reflection surface 32a on the incident side of the optical signal of the multicore optical fiber 3 in the transmission apparatus 2 of FIG. The incident side end, the surface emitting semiconductor laser 20 and the drive circuit are sealed with a sealing member 5. The receiving device 4 of the optical transmission system according to the present embodiment is not illustrated, but, like the transmitting device 2, a reflection film 33 is formed on the reflection surface 32b on the light signal output side of the multi-core optical fiber 3, and the multi-core is formed. The end of the optical fiber 3 on the light signal output side, the light receiving element 40 and the amplifier circuit are sealed with a sealing member 5.

  The reflective film 33 is formed by evaporating gold, aluminum, or the like, for example. Thereby, the light which permeate | transmits the reflective surfaces 32a and 32b is suppressed, and reflection efficiency increases.

  The sealing member 5 uses a material having a refractive index close to the refractive index of the core 30 of the multi-core optical fiber 3, for example, an insulating material such as a translucent epoxy resin or silicone resin. Thereby, refraction and reflection at the interface between the optical element and the lower part of the multi-core optical fiber 3 and air are reduced.

[Third Embodiment]
FIG. 8 shows a configuration example of a transmission apparatus according to the third embodiment of the present invention, where (a) is a front view, (b) is a view in the direction of arrow D in (a), and (c) is FIG. In the first and second embodiments, a multi-core optical fiber is used as an optical transmission line. However, the optical transmission system of the third embodiment uses an optical waveguide, and the others are the first one. This is the same as the embodiment. The following description will focus on differences from the first embodiment.

  In the optical waveguide 13, a plurality of cores 130 a to 130 g (also collectively referred to as cores 130) are arranged hierarchically with respect to the light output surface 120 a of the surface emitting semiconductor laser 120. Specifically, the optical waveguide 13 includes two cores 130a and 130b arranged in the first layer closer to the surface emitting semiconductor laser 120, and three cores 130c arranged in the second layer above them. , 130d, 130e, two cores 130f, 130g arranged in the third layer above them, and a clad formed around the cores 130a-130g and having a refractive index lower than that of the cores 130a-130g 131. The optical waveguide 13 has reflection surfaces 132a inclined at 45 ° with respect to the optical axis of the core 130 at both ends (only one is shown in the figure). In the above-described embodiment, the optical waveguide 13 has the core disposed in the first to third layers, but the core may be disposed in two layers.

  As shown in FIG. 8B, the plurality of cores 130a to 130g of the optical waveguide 13 are light-emitting portions 1210a to 1210g of the surface-emitting type semiconductor laser 120 through the reflection surface 132a (when these are collectively referred to as light emission). Part 1210) and individually optically coupled. Similarly, the plurality of cores 130a to 130g are individually optically coupled to the plurality of light receiving portions of the light receiving element via the other reflection surface of the optical waveguide 13, although illustration is omitted.

  The plurality of cores 130 of the optical waveguide 13 are arranged so as to be shifted in the horizontal direction so that the optical path 23 connecting the light emitting unit 1210 and the corresponding core 130 does not pass through the other cores 130.

  The surface-emitting type semiconductor laser 120 of the present embodiment is different from the surface-emitting type semiconductor laser 20 of the first embodiment in the position of the light emitting unit 1210, and the other configuration is the same as that of the first embodiment. ing. In FIGS. 8A and 8B, reference numeral 120b denotes a mounting surface. In the present embodiment, the distance between adjacent light emitting units 1210 in FIG. 8B is set to be equal.

(Effect of the third embodiment)
According to the third embodiment, the following effects are obtained.
(A) In a configuration using the optical waveguide 13 in which a plurality of cores 130 are hierarchically arranged, the light signal does not pass through the other cores 130 and the light emitting unit 210 and the light receiving element 40 of the surface emitting semiconductor laser 20 are used. The light receiving unit 410 and the core 130 can be optically coupled.
(B) By using a planar light emitting element and a planar light receiving element, it is possible to reduce the height of the transmitting device and the receiving device.

  9A and 9B show an embodiment, in which FIG. 9A is a cross-sectional view of a multicore optical fiber when cores are arranged at the center and apex of a regular hexagon, and FIG. 9B is a rotation angle from the vertical axis of the symmetry axis of the multicore optical fiber. The figure which shows the relationship between (theta) and the horizontal position (position information X) of the core centers P1-P7, (c) is a figure which shows the rotation angle (theta) and the distance between core centers.

  As shown in FIG. 9A, the multi-core optical fiber according to the present embodiment has a distance between adjacent core centers, that is, between P4 and P1, between P4 and P2, between P4 and P3, between P4 and P5, and between P4 and P4. The distances between P6, P4-P7, P1-P2, P2-P5, P5-P7, P7-P6, P6-P3, and P3-P1 are equal. FIG. 9A shows a case where the rotation angle θ of the symmetry axis from the vertical axis is 0 °.

  As shown in FIG. 9 (c), it can be seen that when the rotation angle θ is about 11 °, the distances between the core centers are equal. 2 and 5, even if an alignment error occurs, the light emitting unit 210 is arranged so that the distance between the light emitting unit 210 and the light receiving unit 410 is equal within an error range of ± 5% or ± 10%, for example. The optical signal can be optically coupled with the corresponding core without passing through the other core.

[Modification]
The embodiments of the present invention are not limited to the above-described embodiments, and various modifications and implementations are possible without departing from the scope of the present invention. For example, in each of the above embodiments, the reflection surfaces at both ends of the optical transmission path are provided symmetrically, and the optical elements are arranged below the optical transmission path, but the orientations of the reflection surfaces at both ends of the optical transmission path are the same, One optical element may be disposed below the optical transmission line, and the other optical element may be disposed above the optical transmission line.

  Further, it is possible to omit some of the constituent elements of each of the above embodiments within the scope not changing the gist of the present invention. For example, in each of the above embodiments, the reflecting surfaces are provided at both ends of the optical transmission line, but may be provided only on one side.

  In addition, the constituent elements of the above-described embodiments can be arbitrarily combined within a range that does not change the gist of the present invention. For example, the reflective film and the sealing member of the second embodiment may be applied to the third embodiment.

DESCRIPTION OF SYMBOLS 1 Optical transmission system 2 Transmitter 3 Multi-core optical fiber 3a Center axis 3b Symmetry axis 3c Vertical axis 4 Receiver 5 Sealing member 13 Optical waveguide 20 Surface emitting semiconductor laser 20a Light output surface 20b Mounting surface 21 Support member 21a Receiving surface 22 Circuit board 23 Optical path 30, 30a-30g Core 31 Clad 32a, 32b Reflective surface 33 Reflective film 40 Light receiving element 40a Light input surface 40b Mounting surface 41 Support member 41a Receiving surface 42 Circuit board 43 Optical path 120 Surface emitting semiconductor laser 120a Light output Surface 120b Mounting surface 130, 130a to 130g Core 131 Clad 132a Reflective surface 200 Substrate 210, 210a to 210g Light emitting portion 211 Lower DBR layer 212 Active layer 213 Current confinement layer 213a Aperture 214 Upper DBR layer 215 P-side electrode 215a Openings 216A and 216B Wiring pad Turn 217 Electrode pad 230 N side electrode 400 Substrate 410, 410a to 410g Light receiving part 411 P side electrode 411a Opening 412A, 412B Wiring pattern 413 Electrode pad 414 N side electrode 415A, 415B Wiring pattern 416 Electrode pad 1210, 1210a to 1210g Light emitting part

Claims (3)

A light input / output surface having a plurality of light input / output units for inputting or outputting a plurality of optical signals, and a surface-type optical element having a mounting surface on the opposite side of the light input / output surface;
Multi-core light having a plurality of cores that are optically coupled individually to the plurality of light input / output units via a reflecting surface formed at one end and that are symmetrically and concentrically arranged with respect to at least one symmetry axis on the transverse section With fiber,
The plurality of cores are arranged such that an optical path connecting the light input / output unit and the corresponding core does not pass through the other cores so that the axis of symmetry is inclined with respect to the light input / output surface. Transmitter / receiver. The optical transceiver according to claim 1, wherein the optical element is a surface emitting semiconductor laser. A light output surface having a plurality of light output portions for outputting a plurality of light signals, and a surface-type light emitting element having a mounting surface opposite to the light output surface;
A light input surface having a plurality of light input portions for inputting a plurality of light signals, and a surface type light receiving element having a mounting surface on the opposite side of the light input surface;
The plurality of light output portions are individually optically coupled via a reflection surface formed at one end and the plurality of light input portions and a reflection surface formed at the other end, and at least one symmetry axis on a cross section A multi-core optical fiber having a plurality of cores arranged symmetrically and concentrically ,
The plurality of cores are connected to the light output surface and the light input surface so that respective optical paths connecting the light output unit and the light input unit and the corresponding cores do not pass through the other cores . An optical transmission system arranged with the symmetry axis inclined .

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