JP2006133646A - Bidirectional optical transmission and reception module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bidirectional optical transmission and reception module which achieves high functions in a small module size without increasing the number of components of optical elements even when a plurality of groups of optical transmission and reception functions are built in one module. <P>SOLUTION: A lens function and a wavelength filter function are given to one optical element 601. More particularly, a lens 401 with a wavelength filter 501 vapor deposited in a flat portion is combined with a lens 402 to reduce the number of components of the optical element. Otherwise, one optical element is commonly used for a plurality of semiconductor lasers, so that a plurality of bidirectional optical communication functions are built in one module. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bidirectional optical transceiver module that realizes bidirectional optical transmission, and more specifically to a bidirectional optical transceiver module that realizes a reduction in the number of components used and higher functionality.

  In recent years, FTTH (Fiber To The Home) that realizes large-capacity transmission has attracted attention. In FTTH, as one method for reducing the number of optical fiber cores, bidirectional optical transmission is performed in which an upstream signal and a downstream signal are wavelength-multiplexed and transmitted through a single optical fiber. For the purpose of utilizing for bidirectional optical transmission, an optical transmission / reception module in which an optical transmission module and an optical reception module are integrated has been actively developed.

  A configuration of a conventional bidirectional optical transceiver module is shown in FIG. In FIG. 2, a semiconductor laser 190 converts an input electrical signal into an optical signal having a wavelength λ1. The light receiving element 290 receives the optical signal having the wavelength λ2 and converts it into an electrical signal. Dielectric multilayer filter 590 reflects light having wavelength λ1 and transmits light having wavelength λ2. The optical signal having the wavelength λ 1 output from the semiconductor laser 190 is collimated by the lens 491, reflected by the dielectric multilayer filter 590, and collected by the lens 493 onto the optical fiber 390. The optical signal having the wavelength λ 2 output from the optical fiber 390 is collimated by the lens 493, passes through the dielectric multilayer filter 590, and is collected by the lens 492 onto the light receiving element 290.

By adopting such a configuration, it is possible to perform wavelength-multiplexed optical transmission of upstream signals and downstream signals with a single optical fiber.
Supervised by Koichi Inada, “Guide for introducing optical fiber communications”, Denki Shoin, pp. 144, Figure 3.52, 1989

  However, when the bidirectional optical communication module is configured as shown in FIG. 2, the number of parts of optical elements such as a dielectric multilayer filter and a lens increases, and the module size also increases. In addition, when a plurality of sets of optical transmission / reception functions are built in one module, the number of parts of the optical element increases in proportion to the number of optical transmission / reception functions, so the size of the module increases. Therefore, normally, one set of optical transmission / reception functions is built in one module.

  The present invention has been made in view of the above problems, and by sharing one optical element for optical transmission and optical reception, even when a plurality of sets of optical transmission / reception functions are built in one module, the optical element component Since the number of points does not increase, it becomes possible to realize a high-performance bi-directional optical transceiver module with a small module size.

  According to a first aspect of the present invention, there is provided an electrical-optical conversion element that converts an electrical signal into an optical signal, an optical-electrical conversion element that converts an optical signal into an electrical signal, and an optical fiber that outputs an optical signal output from the electrical-optical conversion element. And an optical element that condenses the optical signal output from the optical fiber onto the opto-electric conversion element, and the optical element reflects light in a specific wavelength band, It has at least a wavelength filter function for transmitting light and a lens function.

  The second invention includes two or more electro-optical conversion elements that convert an electrical signal into an optical signal, two or more optical-electric conversion elements that convert an optical signal into an electrical signal, and an electro-optical conversion element. An optical element that condenses the output optical signal onto the optical fiber and simultaneously condenses the optical signal output from the plurality of optical fibers onto the plurality of photoelectric conversion elements, and the optical element further comprises: It is characterized by having at least a wavelength filter function of reflecting light in a specific wavelength band and transmitting light outside the specific wavelength band, and a lens function.

  According to a third aspect of the present invention, there is provided an electrical-optical conversion element that converts an electrical signal into an optical signal, an optical-electrical conversion element that converts an optical signal into an electrical signal, and power of the optical signal output from the electrical-optical conversion element. The monitoring optical-electrical conversion element to be monitored and the optical signal output from the electrical-optical conversion element are condensed on the optical fiber and the monitoring optical-electrical conversion element, and at the same time, the optical signal output from the optical fiber is optically converted. An optical element that focuses light onto the electrical conversion element, and the optical element has at least a wavelength filter function that reflects light in a specific wavelength band and transmits light outside the specific wavelength band, and a lens function. It is characterized by that.

  According to a fourth aspect of the present invention, there are provided two or more electro-optical conversion elements for converting an electric signal into an optical signal, two or more optical-electric conversion elements for converting an optical signal into an electric signal, and a plurality of electro-optical conversion elements. Two or more monitoring optical-electrical conversion elements for monitoring the power of the optical signal output from the optical signal, and condensing the optical signals output from the electrical-optical conversion element to the optical fiber and the monitoring optical-electrical conversion element And an optical element for condensing the optical signal output from the optical fiber onto the opto-electric conversion element, and the optical element reflects light in a specific wavelength band and transmits light in a wavelength other than the specific wavelength band. It has at least a wavelength filter function to transmit and a lens function.

  According to a fifth invention, in any one of the first to fourth inventions, the optical element includes at least one surface having a wavelength filter and at least one lens surface.

  According to a sixth aspect, in the fifth aspect, the optical element has two lens surfaces, and one of the lens surfaces has a wavelength filter.

  According to a seventh aspect, in the sixth aspect, the curvature radii of the two lens surfaces are different from each other.

  According to an eighth invention, in any one of the first to fourth inventions, the optical element is a combination of a plurality of lenses, the lens comprises at least one plane and at least one lens surface, At least one lens among the plurality of lenses has a wavelength filter on a plane portion thereof.

  According to a ninth aspect, in the eighth aspect, the optical element is composed of two lenses.

  According to a tenth aspect, in the ninth aspect, the two lenses have different curvature radii of the lens surfaces.

  An eleventh invention is characterized in that, in any one of the fifth to tenth inventions, the lens surface of the lens is an aspherical surface.

  According to the eleventh aspect, the optical coupling efficiency can be increased by using the aspheric lens.

  According to a twelfth aspect, in any one of the fifth to tenth aspects, the lens is a hemispherical lens.

  According to the first invention, since the optical transmission and the optical reception are performed by one optical element, the bidirectional optical transmission / reception module that realizes the wavelength division multiplexing optical transmission of the upstream signal and the downstream signal with a small number of components and a small size is provided. Can be configured.

  According to the second aspect, since a plurality of optical transmission / reception functions can be realized by one optical element, a plurality of both optical transmission / reception functions can be integrated in one optical module.

  According to the third aspect of the invention, since it becomes possible to monitor the power of the optical signal output from the electro-optical conversion element, a dual optical transceiver module capable of APC (Auto Power Control) control is configured. Can do.

  According to the fourth aspect of the invention, since the power of the optical signal output from the plurality of electro-optical conversion elements can be monitored, the APC (Auto Power) is applied to each electro-optical conversion element. It is possible to configure a dual optical transmission / reception module that can be controlled.

  According to the fifth aspect, the optical element according to the first aspect can be realized with a single lens.

  According to the seventh aspect, it is possible to increase the coupling efficiency between the electro-optical conversion element and the optical fiber as compared with the case of the same radius of curvature.

  According to the eighth aspect, by combining a plurality of lenses, it is possible to optically couple the electro-optical conversion element, the optical-electrical conversion element, and the optical fiber with high efficiency.

  According to the tenth aspect, the coupling efficiency between the electro-optical conversion element and the optical fiber can be increased as compared with the case of the same radius of curvature.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 3 to 11.

(Embodiment 1)
FIG. 1 is a block diagram showing a basic configuration of a bidirectional optical transceiver module according to Embodiment 1 of the present invention. The bidirectional optical transmission / reception module in this embodiment includes a semiconductor laser 101, a photodiode 201, and an optical element 601.

  First, the operation of this module will be described. The semiconductor laser 101 outputs light having a wavelength λ1. Usually, light output from a semiconductor laser propagates while spreading. Light of wavelength λ1 is incident on the lens surface of the optical element 601 and converted into parallel rays. Here, a wavelength filter having transmission characteristics as shown in FIG. 3 is built in the optical element 601 in the present embodiment, and light of wavelength λ1 is totally reflected. When the light having the wavelength λ 1 reflected by the wavelength filter is emitted from the optical element 601, it passes through the lens surface of the optical element 601 and is condensed on the optical fiber 301. On the other hand, the light of wavelength λ2 output from the optical fiber 301 passes through the lens surface of the optical element 601 and is converted into parallel rays. The light of wavelength λ2 passes through the wavelength filter having the transmission characteristics shown in FIG. 3 and is condensed on the light receiving surface of the photodiode 201 by the lens of the optical element 601.

  FIG. 4 shows a configuration example of the optical element 601. In this configuration example, two spherical lenses 401 and 402 and a wavelength filter 501 are used. A wavelength filter 501 is deposited on the flat surface of the spherical lens 401. Generally, a dielectric multilayer film is used as the wavelength filter. The optical element 601 has a structure in which the flat surface portion of the spherical lens 401 on which the wavelength filter 501 is deposited is combined with the flat surface portion of the other spherical lens 402.

  In this configuration example, the wavelength filter is deposited on the spherical lens 401. However, as shown in FIG. 5, the wavelength filter element 502 may be bonded to the spherical lens 401. Further, an aspherical lens having a flat portion may be used instead of the spherical lenses 401 and 402. By using an aspheric lens, it becomes possible to reduce aberrations compared to a spherical lens, and the coupling efficiency between the semiconductor laser 100 and the optical fiber 300 and between the optical fiber and the photodiode can be improved.

  Further, as shown in FIG. 11, the coupling efficiency between the semiconductor laser 100 and the optical fiber 300 can be increased by changing the radius of curvature of the two spherical lenses. That is, since the NA of the light emitted from the semiconductor laser 100 and the NA of the optical fiber generally do not coincide with each other, the NA of the light emitted from the semiconductor laser 100 is changed to light by changing the radius of curvature of the two spherical lenses. Conversion can be made to be comparable to the NA of the fiber.

  According to the above embodiment, since the lens has a wavelength filter function, the number of components and the mounting space can be reduced, so that bidirectional light that performs wavelength division multiplexing optical transmission of upstream and downstream signals is possible. The transmission / reception module can be downsized.

(Embodiment 2)
FIG. 6 shows the configuration of the bidirectional optical transceiver module according to Embodiment 2 of the present invention. The basic configuration is the same as that of the first embodiment shown in FIG. There are two differences from FIG. 1. One is that the wavelength filter built in the optical element 603 transmits light slightly at the wavelength λ1 of the light emitted from the semiconductor laser 101 as shown in FIG. It is a point to do. The other is that it has a monitoring photodiode 210 that detects the intensity of light emitted from the semiconductor laser 101. Here, the transmittance at the wavelength λ1 of the wavelength filter built in the optical element 603 is determined by the minimum light receiving sensitivity of the monitoring photodiode 210, and is set to such a value that the emission power of the semiconductor laser 101 can be sufficiently monitored. The

  According to the above-described embodiment, the emission power of the semiconductor laser 101 can be detected with the size obtained by adding the monitoring photodiode to the configuration in the first embodiment. Therefore, APC (Auto Power Control: constant light output control) ) A small bidirectional optical transceiver module capable of operation can be realized.

(Embodiment 3)
FIG. 8 shows the configuration of the bidirectional optical transceiver module according to Embodiment 3 of the present invention. The basic configuration is the same as that of the first embodiment shown in FIG. 1 is different from FIG. 1 in that a plurality of semiconductor lasers 101 to 103 and a plurality of photodiodes 201 to 203 are provided.

  The light emitted from the semiconductor laser 101 enters the optical fiber 301, and the light emitted from the optical fiber 301 enters the photodiode 201. Similarly, the semiconductor lasers 102 and 103 and the optical fibers 302 and 303 and the optical fibers 302 and 303 and the photodiodes 202 and 203 are optically coupled, respectively. The semiconductor lasers 101 to 103 are arranged by shifting the optical axes so that the light beams do not interfere with each other even if the wavelengths of the emitted lights are the same.

  Here, in this embodiment, an example in which three sets of semiconductor lasers and photodiodes are incorporated is shown, but a bidirectional optical transceiver module can be realized with the same configuration even if there are three or more sets. It is also possible to incorporate a plurality of monitoring photodiodes by setting the characteristics of the wavelength filter incorporated in the optical element 601 to the characteristics shown in the second embodiment.

  According to the above embodiment, since one optical element can be shared for the optical coupling of the semiconductor lasers 101 to 103 and the optical fibers 301 to 303 and the optical coupling of the optical fibers 301 to 303 and the photodiodes 201 to 203, A plurality of bidirectional optical communication functions can be incorporated in one module without increasing the number of components of the optical system, and the bidirectional optical communication module can be downsized and enhanced in function at low cost.

(Embodiment 4)
FIG. 9 shows the configuration of the bidirectional optical transceiver module according to Embodiment 4 of the present invention. The basic configuration is the same as that of the first embodiment shown in FIG. The difference from FIG. 1 is that the shape of the optical element 602 is different.

  FIG. 10 shows a configuration example of the optical element 602. In the optical element 602 in this configuration example, the following specific range functions as a lens surface. First, a range in which light incident on the optical element 602 from the semiconductor laser 100 passes (410), second, a range in which light emitted from the optical element 602 to the optical fiber 300 passes (411), third, optical from the optical fiber 300 A range in which light incident on the element 602 passes (411), and a range in which light incident on the photodiode 200 from the optical element 602 passes (412). Any shape outside the above range does not affect the function of the optical element 602. In this configuration example, as in the first embodiment, the optical element 602 is composed of a plurality of parts, and a wavelength filter is vapor-deposited on a flat portion of these parts. A similar configuration can be obtained by adhering a wavelength filter element instead of depositing the wavelength filter 501.

  According to the above embodiment, the curvatures of the lens surfaces 410 to 412 are individually set so that the optical device (semiconductor laser 100, photodiode 200, optical fiber 300) and the optical element 602 can be optimally coupled. Therefore, a highly efficient bidirectional optical transceiver module can be configured.

  Note that in this embodiment mode, a configuration in which the monitor photodiode is not provided is described; however, the monitor photodiode can be provided by increasing the lens surface of the optical element 602. Effects similar to those shown can be obtained.

  In this embodiment, an example in which a pair of bidirectional optical transmission / reception functions are incorporated is described. However, by increasing the lens surface of the optical element 602, a plurality of bidirectional optical transmission / reception functions can be incorporated. There can be obtained an effect similar to that shown in the third embodiment.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical transmission system that performs bidirectional communication with a single optical fiber, and is effective for downsizing and enhancement of functionality of a bidirectional optical communication module.

Configuration diagram of bidirectional optical transceiver module according to Embodiment 1 of the present invention Configuration diagram of conventional bidirectional optical transceiver module The figure explaining the transmission characteristic of the wavelength filter in Embodiment 1 of this invention The figure explaining the structure of the optical element in Embodiment 1 of this invention The figure explaining the structure of the optical element in Embodiment 1 of this invention Configuration diagram of bidirectional optical transceiver module according to Embodiment 2 of the present invention The figure explaining the transmission characteristic of the wavelength filter in Embodiment 2 of this invention Configuration diagram of bidirectional optical transceiver module according to Embodiment 3 of the present invention Configuration diagram of bidirectional optical transceiver module according to Embodiment 4 of the present invention The figure explaining the structure of the optical element in Embodiment 4 of this invention. The figure explaining the structure of the optical element in Embodiment 1 of this invention

Explanation of symbols

100, 101, 102, 103, 190 Semiconductor laser 200, 201, 202, 203 Photodiode 210 Monitor photodiode 290 Light receiving element 300, 301, 302, 303, 390 Optical fiber 401, 402, 491, 492, 493 Lens 410 , 411, 412 Lens surface 501, 590 Wavelength filter 502 Wavelength filter element 601, 602, 603 Optical element λ1, λ2 Wavelength of light emitted from the semiconductor laser

Claims (12)

An electro-optical conversion element for converting an electric signal into an optical signal;
An opto-electric conversion element for converting an optical signal into an electric signal;
An optical element that condenses the optical signal output from the electric-optical conversion element onto an optical fiber, and simultaneously condenses the optical signal output from the optical fiber onto the optical-electrical conversion element;
The bidirectional optical transceiver module further includes at least a wavelength filter function that reflects light in a specific wavelength band and transmits light in a wavelength other than the specific wavelength band, and a lens function. Two or more electro-optical conversion elements for converting an electrical signal into an optical signal;
Two or more photoelectric conversion elements that convert optical signals into electrical signals;
One optical element for condensing the optical signals output from the plurality of optical fibers onto the plurality of optical-electrical conversion elements simultaneously with condensing the optical signals output from the electro-optical conversion elements onto an optical fiber; Comprising
The bidirectional optical transceiver module further includes at least a wavelength filter function that reflects light in a specific wavelength band and transmits light in a wavelength other than the specific wavelength band, and a lens function. An electro-optical conversion element for converting an electric signal into an optical signal;
An opto-electric conversion element for converting an optical signal into an electric signal;
A monitoring optical-electrical conversion element for monitoring the power of the optical signal output from the electrical-optical conversion element;
The optical signal output from the electrical-optical conversion element is condensed on the optical fiber and the monitoring optical-electrical conversion element, and at the same time, the optical signal output from the optical fiber is condensed on the optical-electrical conversion element. An optical element,
The bidirectional optical transceiver module further includes at least a wavelength filter function that reflects light in a specific wavelength band and transmits light in a wavelength other than the specific wavelength band, and a lens function. Two or more electro-optical conversion elements that convert electrical signals into optical signals;
Two or more photoelectric conversion elements that convert optical signals into electrical signals;
Two or more monitoring optical-electrical conversion elements for monitoring the power of the optical signals output from the plurality of electrical-optical conversion elements;
The optical signal output from the electrical-optical conversion element is condensed on the optical fiber and the monitoring optical-electrical conversion element, and at the same time, the optical signal output from the optical fiber is condensed on the optical-electrical conversion element. Comprising one optical element,
The bidirectional optical transceiver module further includes at least a wavelength filter function that reflects light in a specific wavelength band and transmits light in a wavelength other than the specific wavelength band, and a lens function. 5. The bidirectional optical transceiver module according to claim 1, wherein the optical element includes at least one surface having a wavelength filter and at least one lens surface. 6. 6. The bidirectional optical transceiver module according to claim 5, wherein the optical element has two lens surfaces, and one of the lens surfaces has a wavelength filter. The bidirectional optical transceiver module according to claim 6, wherein the two lens surfaces have different radii of curvature. The optical element is a combination of a plurality of lenses, and the lens includes at least one plane and at least one lens surface, and at least one of the plurality of lenses has a plane portion thereof. The bidirectional optical transceiver module according to claim 1, further comprising a wavelength filter. 9. The bidirectional optical transceiver module according to claim 8, wherein the optical element is composed of two lenses. The bidirectional optical transceiver module according to claim 9, wherein the two lenses have different curvature radii of lens surfaces. The bidirectional optical transceiver module according to claim 5, wherein a lens surface of the lens is an aspherical surface. The bidirectional optical transceiver module according to claim 5, wherein the lens is a hemispherical lens.

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