JPH03144602A - Two-way light emission and reception module - Google Patents

Abstract

PURPOSE:To reduce the size of a device by connecting a light emission module, a light reception module, a beam splitter module, and a receptacle module directly into one body. CONSTITUTION:The light emission module 11, light reception module 13, receptacle module 15, and beam splitter module 17 are connected in series and united. The light emission module 11 is constituted by fitting a light emitting element 113 and a coupling lens 115 in a case 111 and the light reception module 13 is constituted by fitting a light receiving element 113 and a coupling lens 135 in a case 131. Further, the beam splitter module 17 is constituted by fitting a beam splitter 173 and a Faraday rotator 171 in a case 175 and this module transmits light with specific wavelength and reflects light with other specific wavelength. Consequently, the need for a connector and an optical fiber which connect the respective modules is eliminated to reduce the size of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a bidirectional light emitting/receiving module used in a wavelength multiplexing optical communication system that performs transmission and reception by sharing one optical fiber.

[Conventional technology]

Conventionally, when wavelength multiplexing transmission of light is performed by sharing one optical fiber, a light receiving/emitting system comprising a demultiplexer and a receiving/emitting module is attached to both ends of the optical fiber.
It was configured to receive and emit light between a light emitting element and a light receiving element which are attached to the bidirectional light receiving and emitting system at both ends.

FIG. 6 is a diagram showing a conventional bidirectional light receiving and emitting system of this type.

As shown in the figure, this bidirectional light receiving and emitting system 600a,
b are attached to both ends of the optical fiber 607.

Note that the bidirectional light receiving and emitting systems 600a and 600b each include a light emitting module 601a+b consisting of a light emitting element such as a laser diode or a light emitting diode, and a 5i-PIN.
, Si-APD, and other light receiving elements, and demultiplexers 605a, b that transmit light of a predetermined wavelength (input, ) and reflect light of another predetermined wavelength (λ,).
It is equipped with. And these light emitting modules 601
a, b and light receiving modules 603a, b are respectively optical fibers 611a, b and connector 609a.

b to the duplexers 605a and 605b.

Here, the light emitting module 601a emits light with a wavelength of λ8, and the light emitting module 601b emits light with a wavelength of λ8. Further, the demultiplexers 605a and 605b are configured to transmit light at the input wavelength and reflect light at the input wavelength, respectively.

And the wavelength ^1 emitted from the light emitting module 601a
The light passes through an optical fiber 611a, a splitter 605a, an optical fiber 607, a splitter 605b, and an optical fiber 611.
b and is received by the light receiving module 603b.

On the other hand, the light of wavelength λ emitted from the light emitting module 601b passes through the optical fiber 611b and then passes through the demultiplexer 600.
5b and guided to an optical fiber 607, then reflected by a demultiplexer 605a, guided to an optical fiber 611a, and received by a light receiving module 603a.

In this way, bidirectional wavelength multiplexing transmission is performed.

[Problem to be solved by the invention]

However, the bidirectional light receiving and emitting system 600 as described above
In a and b, an optical fiber 61 is connected between each module.
1a, b and connectors 609a, b, but there is a problem in that the bidirectional light receiving/emitting systems 600a, b cannot be miniaturized because of the optical fibers 61fa, b, etc. Furthermore, the duplexers 605a and 605b are large in size, which also explains the bidirectional light receiving and emitting system 600a.
, b was hindering miniaturization.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a bidirectional light emitting/receiving module in which a bidirectional light emitting/receiving system is modularized, which is compact and integrated, and whose assembly and adjustment are easy. .

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a bidirectional light receiving/emitting module including a light emitting element, a coupling lens that converts the light emitted from the light emitting element into parallel light, a light receiving element, and a coupling lens that converts the incident parallel light into parallel light. A light receiving module including a coupling lens that focuses light on the light receiving element, a beam splitter module that transmits light of a predetermined wavelength and reflects light of another predetermined wavelength, and a coupling lens that focuses parallel light onto an optical fiber. At least one receptacle module comprising
Each of the modules is directly connected to each other to form an integrated structure.

[Effect]

As described above, the light emitting module, light receiving module, beam splitter module, and receptacle module are directly connected and integrated to form a bidirectional light receiving/emitting module, so there is no need for conventional connectors or optical fibers to connect each module. Therefore, the device can be made smaller.

In addition, the light emitted from the light emitting module becomes parallel light by the coupling lens, the light entering the light receiving module is parallel light, and the light entering the receptacle module is also parallel light, so each of these modules is connected to a beam splitter. Adjustments when installing directly to the module are as follows:
Since only the adjustment of optical axis alignment between the modules is required, assembly is facilitated.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a side sectional view showing a bidirectional light receiving/emitting module 1 according to the present invention.

As shown in the figure, this bidirectional light receiving/emitting module 1 is constructed by directly connecting a light emitting module 11, a light receiving module 13, and a receptacle module 15 to a beam splitter module 17 and integrating them.

Each module will be explained below.

The light emitting module 11 has a light emitting element 113 inside the case 111.
and a coupling lens 115 are attached.

Here, the light emitting element 113 is composed of a laser diode, a light emitting diode, etc., and the coupling lens 115 is composed of a ball lens in this embodiment.

Note that this coupling lens 115 is arranged at a position to convert the light emitted from the light emitting element 113 into parallel light.

The light receiving module 13 has a light receiving element 133 inside the case 131.
and a coupling lens 135 are attached.

Here, the coupling lens 135 is composed of a spherical lens, and is arranged at a position where parallel light incident from the outside is focused on the light receiving element 133.

The receptacle module 15 is composed of a case 151, a stopper 153, and a coupling lens 155.

Here, an insertion hole 157 is formed in the center of the case 151 into which a ferrule (not shown) holding an optical fiber on its central axis is inserted.

Further, the stopper 153 is formed in a cylindrical shape, and the coupling lens 155 is composed of a spherical lens.

The stopper 153 and the coupling lens 155 are inserted into the insertion hole 157 of the case 151 and fixed.

Next, the beam splitter module 17 is installed in the case 175.
There is a beam splitter 173 and a Faraday rotator 171 inside.
It is configured by installing.

Here, the case 175 has a hole formed therein, and the hole is open in three directions (left and right downward directions in the figure). Note that the light emitting module 11, the light receiving module 13, and the receptacle module 15 are directly attached to each open portion of the case 175, as shown in the figure.

The beam splitter 173 is arranged approximately at the center of the case 175 and is fixed at an angle of 45 degrees with respect to the optical axis. As shown in FIG. 2, this beam splitter 173 has a polarizing beam splitter part p made of a dielectric multilayer film having a polarizing beam splitter function to isolate returning light on its upper left side, and A wavelength selection filter part q is formed on the lower surface side to transmit or reflect the incident light depending on the wavelength of the incident light.

Further, the Faraday rotator 171 is attached to the opening of the case 175 on the side where the light emitting module 11 is attached. This Faraday rotator 171 is constructed by attaching a magneto-optic crystal 171a made of, for example, a Bi-substituted garnet film inside a ring-shaped magnet 171b.

Next, to assemble this bidirectional light receiving and emitting module 1, the surface of the light emitting module 11 on which the coupling lens 115 is attached is directly fixed to the surface of the beam subric module 17 on the side on which the Faraday rotator 171 is attached, and the beam The surface of the light receiving module 13 on which the coupling lens 135 is attached is directly fixed to the lower surface of the splitter module 17, and the coupling lens 155 of the receptacle module 15 is further fixed to the right surface of the beam splitter module 17.
Directly fix the side to which it is attached. Note that laser welding or a fixing jig is used to fix these modules.

FIG. 3 is a diagram showing an example of use of this bidirectional light emitting/receiving module 1.

First, two sets of bidirectional light emitting/receiving modules 1 shown in FIG. 1 are prepared. These bidirectional light receiving and emitting modules 1 and 1' are connected to both ends of an optical fiber 31, respectively, as shown in FIG.

The bidirectional light receiving/emitting modules 1, 1' are connected to both ends of the optical fiber 31 by connecting connectors 33, 33', respectively.

At this time, the optical fiber 31 is inserted to the position of the stopper 153 of the receptacle module 15 shown in FIG.

In the bidirectional light emitting/receiving module 1 on the left side, the light emitting module 11 emits light of a certain wavelength, and the beam splitter module 17 transmits light of a wavelength ^1 and reflects light of a wavelength λ. is formed.

On the other hand, in the bidirectional light emitting/receiving module 1' on the right side, light with a wavelength λ is emitted from the light emitting module 11', and the beam splitter module 17' transmits light with a wavelength λ and reflects light with a wavelength λ. It is formed to do so.

Next, the transmission and reception of light will be explained.

First, as shown in FIG. 1, light with a wavelength λ emitted from the light emitting module 11 of the left bidirectional light receiving/emitting module 1 is turned into parallel light by the coupling lens 115, and the plane of polarization is changed to 45 by the Faraday rotator 171. The beam is rotated by .degree. and then transmitted through the beam splitter 173. In this case, the polarization direction of the light at the input wavelength is adjusted by rotating the light emitting element 113 so that the light completely passes through the beam splitter 173. The parallel light transmitted through the beam splitter 173 is focused into the optical fiber 31 by the coupling lens 155.

This light is then transmitted through the optical fiber 31 and reaches the bidirectional light receiving/emitting module 1' shown in FIG.

Next, the light having the wavelength λ that reaches the bidirectional light emitting/receiving module 1' is transferred to the coupling lens 15 in the receptacle module 15'.
5' into parallel light, which is then reflected by the beam splitter 173' in the beam splitter module 17' toward the light receiving module 13', and then reflected by the coupling lens 135'.
The light is focused on the light receiving element 133', and information within the party is detected.

Similarly, the light of wavelength λ emitted from the right light emitting module 11' is transmitted to the beam splitter module 17'.
The light passes through the receptacle module 15', is introduced into the optical fiber 31, and is introduced into the receptacle module 15 of the bidirectional light emitting/receiving module 1 on the left side. And this wavelength λ.

The light is reflected by the beam splitter module 17 and focused on the light receiving element 133 in the light receiving module 13,
Information within the party is detected. Furthermore, the emitted and returned light component from the light emitting module 11 is also reflected at the polarizing beam splitter section of the beam splitter module 17 . Therefore, the light receiving element 133 is installed so as to remove it.

As described above, the light emitted from the light emitting module 11 to the outside is parallel light, the light input to the light receiving module 13 is parallel light, and the light input to the receptacle module 15 is also parallel light.

Therefore, when each of these modules is directly attached to the beam splitter module 17, the only adjustment required is alignment of the optical axes between the modules, and the assembly is easy.

Note that an isolator is constituted by the Faraday rotator 171 shown in FIG. 1 and the polarizing beam splitter part p formed in the beam splitter 173, and its function will be explained.

That is, as shown in FIG. 1, the plane of polarization of the light emitted from the light emitting module 11 is rotated by 45 degrees by the Faraday rotator 171, and the polarization plane of the light is rotated by 45 degrees to form a polarizing beam splitter section p. This transmitted light is transmitted through the beam splitter 173, but the reflected light that is reflected by the end face of the inner optical fiber 31 and scattering inside the optical fiber 31 passes through the beam splitter 173 again and a part of it reaches the Faraday rotator 171. However, this 45
The reflected light that has been rotated is this Faraday rotator 171
Since the light emitting element 113 is further rotated by 45@,
It is perpendicular to the polarization direction of the oscillated light. Therefore, since this reflected light does not have a resonance component with the light emitted from the light emitting element 113, no interference noise is generated.

FIG. 4 is a side sectional view showing another embodiment configured to further multiplex light using the bidirectional light emitting/receiving module 1 according to the present invention.

As shown in the figure, the bidirectional light emitting/receiving module 1 in this embodiment has a first beam splitter module 11-1, a second light emitting module 11-2, a light receiving module 13, and a receptacle module 15, respectively. Yule 17-1 and second beam splitter module 17
-2.

Here, the first light emitting module 11-1 has a configuration similar to that of the light emitting module 11 in FIG. 1, and emits light at a certain wavelength.

The second light emitting module 11-2 also has a configuration similar to that of the light emitting module 11 in FIG. 1, and emits light with wavelengths within the range.

Further, a portion of the wavelength selection filter of the fourth beam splitter module 17-1 transmits the light having the wavelength λ1 and reflects the light having the wavelength ^.

In addition, a part of the wavelength selection filter of the second beam splitter module 17-2 transmits light of wavelengths λ and λ, and
, reflects the light of.

FIG. 5 is a diagram showing an example of use of this bidirectional light receiving/emitting module 1.

As shown in the figure, this bidirectional light receiving/emitting module 1 is connected to the left side of an optical fiber 31 by a connector 33. Further, on the right side of this optical fiber 31, a bidirectional receiving/emitting module 1' having substantially the same structure as this bidirectional receiving/emitting module 1 is connected.

This right bidirectional light emitting/receiving module 1' and the receptacle module 15' transmit light of wavelength λ, and transmit light of wavelength λ8.
a first beam splitter module 17' that reflects the light of
-1 and the wavelengths λ1 and λ.

a second beam splitter module 17'-2 that transmits light of wavelength λ and reflects light of wavelength λ; and first light receiving module 13.
'-1, a second light receiving module 13-2, and a light emitting module 11'-1 that emits light of wavelength λ.

Next, the operation of the bidirectional light emitting/receiving modules 1, 1' will be explained.

First, the light of wavelength ^ emitted from the first light emitting module 11-1 on the left side is transmitted to the first beam splitter module 17-1.
The wavelength λ that passed through the zero-order optical fiber 31 after passing through the first and second beam splitter modules 17-2 and the receptacle module 15 and being guided into the optical fiber 31;
The light passes through the receptacle module 15' and the second beam splitter module 17'-2, is reflected by the first beam splitter module 17'-1, and is focused on the light receiving module 13'-1. Ru.

Further, the light having the wavelength λ emitted from the second light emitting module 11-2 on the left side is transmitted to the second beam splitter module 17-2.
After being reflected at 2, the light passes through the receptacle module 15 and is guided into the optical fiber 31. Next, the wavelength light that has passed through the optical fiber 31 passes through the receptacle module 15', is reflected by the second beam splitter module 17'-2, and is transferred to the light receiving module 13'-2.
The light is focused on.

Furthermore, the wavelength λ emitted from the right light emitting module 11'
, the light from the first beam splitter module 17'-1
The beam passes through the second beam splitter module 17'-2 and the receptacle module 15' and is guided into the optical fiber 31.

Next, the light having the wavelength λ that has passed through the optical fiber 31 passes through the receptacle module 15 and the second beam splitter module 17-2, and then is reflected by the first beam splitter module 17-1 and received. The light is focused on the module 13.

In this way, even if the types of light transmitted through the optical fiber 31 increase, the bidirectional light receiving/emitting module 1 according to the present invention can reduce the number of modules constituting the bidirectional light receiving/emitting module 1. Since it is only necessary to increase the number of units as needed and connect them directly, it is easy to recombine them according to the purpose.

Although the embodiments of the bidirectional light emitting/receiving module according to the present invention have been described in detail above, the present invention is not limited thereto and can be modified in various ways. a light-emitting module equipped with a coupling lens that converts the incident light into parallel light; a light-receiving module equipped with a coupling lens that focuses the incident parallel light on the light-receiving element; A beam splitter module that reflects light of a predetermined wavelength of Any structure may be used as long as it is a bidirectional light emitting/receiving module.

〔Effect of the invention〕

As explained in detail above, according to the bidirectional light emitting/receiving module according to the present invention, the light emitting module, the light receiving module, the beam splitter module, and the receptacle module can be directly connected and integrated. There is no need for connectors or optical fibers to connect modules, which has the excellent effect of making the device more compact.

In addition, the light emitted from the light emitting module to the outside is parallel light, and the light entering the light receiving module is parallel light.
The light incident on the receptacle module is also parallel light. Therefore, when these modules are directly attached to the beam splitter module, only the adjustment of the optical axis alignment between the modules is necessary, and the assembly is easy.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a bidirectional light emitting/receiving module 1 according to the present invention, FIG. 2 is a side view showing a beam splitter 173, and FIG. 3 is a diagram showing an example of use of this bidirectional light emitting/receiving module 1. FIG. 4 is a side sectional view showing another embodiment of the bidirectional light receiving/emitting module 1 according to the present invention, FIG. 5 is a view showing an example of use of this bidirectional receiving/emitting module 1, and FIG. FIG. In the figure, 1... bidirectional light receiving/emitting module, 11... light emitting module, 113... light emitting element, 115... coupling lens, 13... light receiving module, 133... light receiving element, 135... ... Combined lens, 15... Receptacle module, 155... Combined lens, 17...
Beam splitter module, 171... Faraday rotator, 173... Beam splitter, q... Part of wavelength selection filter, p... Polarizing beam splitter section,
175...Case, 31...Optical fiber.

Claims (3)

[Claims] (1) In a bidirectional light emitting/receiving module that is attached to the end of a single optical fiber and emits light of a predetermined wavelength and receives light of other wavelengths, the module includes a light emitting element and the light emitted from the light emitting element. A light emitting module equipped with a coupling lens that converts parallel light into parallel light; a light receiving module equipped with a coupling lens that focuses the incident parallel light onto the light receiving element; and a light receiving module that transmits light of a predetermined wavelength and transmits light of another predetermined wavelength. a beam splitter module that reflects the light of A bidirectional light receiving and emitting module. (2) The beam splitter module has a flat beam splitter arranged in a case at an angle of 45 degrees with respect to the optical axis. 2. The bidirectional light emitting/receiving module according to claim 1, further comprising a wavelength selection filter that reflects light having a wavelength of . (3) A Faraday rotator that rotates the polarization plane of light emitted from the light emitting module by 45 degrees is installed inside the case of the beam splitter module, and a polarized beam is attached to the side of the beam splitter that does not form the wavelength selection filter. 3. The bidirectional light receiving/emitting module according to claim 2, wherein an optical isolator is constructed by forming a splitter.