JP2002319905A - Optical two-way multiplex transmission system and optical module to be used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system, with which optical two-way multiplex transmission can be performed with the transmission rate of high speed only by using just two kinds of wavelength without increasing a number of kinds of wavelength. SOLUTION: A first optical two-way multiplex transmission system 181 performs optical two-way multiplex transmission through one optical transmission line 17 by using just two-wavelength (generally λ1 and λ2 are to be used for forward transmission and λ1 ' and λ2 ' are to be used for backward transmission but especially the conditions of λ1 =λ1 ' and λ2 =λ2 ' are established). By adding a second optical two-way multiplex transmission system 182 having the same configuration and mutually parallel executing the similar transmission in two systems, the transmission can be performed with the double rate as high as a case of one system without increasing a number of kinds of wavelength. Generally, by providing 1st to n-th optical two-way multiplex transmission systems 181 to 18n , transmission can be performed with an n-fold rate by using only two kinds of wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical transmission system, and more particularly to an optical bidirectional multiplex transmission system for multiplexing a plurality of optical signals having different wavelengths and transmitting the multiplexed signals in both directions.

[0002]

2. Description of the Related Art Conventionally, as a bidirectional optical transmission system using this kind of wavelength multiplexing, the configuration shown in FIG. 10 is generally used. In FIG. 10, the conventional optical bidirectional multiplex transmission system includes a forward transmission system 7 and a reverse transmission system 7 '. The forward transmission system 7 includes optical transmission units 1a to 1d,
It includes optical transmission lines 2a to 2d, an optical multiplexer 3, a main optical transmission line 4, an optical demultiplexer 5, and optical receiving units 6a to 6d. The reverse transmission system 7 'includes optical transmission units 1a' to 1d ', optical transmission lines 2a' to 2d ', an optical multiplexer 3', a main optical transmission line 4 ', and an optical demultiplexer 5'. And light receiving units 6a 'to 6d'.

In the forward transmission system 7, the optical transmission units 1a to 1d
Is composed of, for example, a semiconductor laser and a drive circuit, and transmits optical signals of four different wavelengths λ1, λ2, λ3, λ4 to the optical transmission lines 2a to 2d, respectively. The optical multiplexer 3 is
Light of four wavelengths input through the optical transmission lines 2a to 2d is multiplexed with each other, and the obtained optical multiplexed signal is output to the main optical transmission line 4. The optical demultiplexer 5 converts the optical multiplexed signal input through the main optical transmission line 4 into wavelengths λ1, λ2, λ3,
The signal is branched into optical signals of λ4 and output to four optical transmission lines 1e to 1h. Each of the light receiving units 6a to 6d includes, for example, a photodiode, an amplifier circuit, a signal reproducing circuit, and the like, and transmits an optical signal having a wavelength of λ1, λ2, λ3, λ4 to the optical transmission line 2.
a to 2d. With such a configuration, data can be transmitted in the forward direction at a transmission rate that is four times that in the case of transmission using one optical wavelength.

[0004] The same operation as described above is performed in the reverse transmission system 7 ', whereby the transmission in one optical wavelength is performed.
Data can be transmitted in the reverse direction at twice the transmission rate.

[0005]

The above-mentioned conventional optical bidirectional multiplex transmission system has two transmission systems of a forward direction and a reverse direction, and each transmission system multiplexes optical signals having four different wavelengths. By performing the transmission operation, a transmission rate four times that in the case of transmitting with one optical wavelength in each of the forward direction and the reverse direction is realized. In order to realize a higher transmission rate, such as 5 times, 6 times,.
One, six, etc.

[0006] In this case, however, many types of light sources having different wavelengths must be prepared. In addition, as the number of wavelength types increases, the intervals between the wavelengths become closer, so it is necessary to perform highly accurate wavelength control to prevent interference between optical signals, and additional devices and peripheral circuits are added for that purpose. Must. That is, there is a problem that if the transmission rate is to be increased, the price of the system is rapidly increased.

Therefore, an object of the present invention is to provide a system capable of performing optical bidirectional multiplex transmission at a high transmission rate using only two types of wavelengths without increasing the number of wavelength types. is there.

[0008]

Means for Solving the Problems and Effects of the Invention The present invention has solved the above-mentioned problems by the following means. In this section, for the purpose of clarifying the correspondence with the embodiments and facilitating the understanding of the present invention, reference numerals and the like are given to respective components. It should be noted that these reference numbers and the like do not limit the present invention.

The first invention is an optical bidirectional multiplex transmission system (FIG. 1) for multiplexing two optical signals having mutually different wavelengths and transmitting the multiplexed signals in both directions, and comprises a pair of optical transmitting and receiving devices (20 and 20 ′), and each optical transceiver (2
0) are mutually different wavelengths (λ1 and λ2)
First and second for transmitting two optical signals having
Optical transmission units (11a and 11b), two input terminals and one
An optical multiplexer (13) for multiplexing and outputting two optical signals having different wavelengths inputted thereto, and having one input terminal and two output terminals. An optical demultiplexer (1) that demultiplexes an input optical multiplexed signal into two optical signals having different wavelengths and outputs the demultiplexed optical signal.
4) first and second optical receivers (12a and 12b) for receiving two optical signals having different wavelengths (λ1 ′ and λ2 ′), and an optical signal input to the first port. A three-terminal circulator (15) for outputting an optical signal output from the second port and input to the second port from the third port, wherein the second terminal of the three-terminal circulator (15) provided in each optical transmitting / receiving device is provided; The ports are connected to each other via an optical transmission line (17), and in each optical transmitting and receiving device, the first and second optical transmitting units (11a and 11b) are respectively connected to two input terminals of an optical multiplexer (13). Connected, the output end of the optical multiplexer (13) is connected to the first port of the three-terminal circulator (15), and the third port of the three-terminal circulator (15) is connected to the optical demultiplexer (1).
4) and two output terminals of the optical demultiplexer (14) are connected to the first and second optical receiving units (12a and 12a).
b).

In the first invention, optical multiplex transmission using two wavelengths in the forward direction is performed as follows. A first optical transmission unit (11a) in one of the optical transmission / reception devices (20);
And a second wavelength (λ2) transmitted from the second optical transmitter (11b).
Is input to the optical multiplexing unit (13), and the optical multiplexing unit (13) outputs optical multiplexed signals (wavelengths λ1 and λ2). This optical multiplex signal is supplied to a three-terminal circulator (1
5) is input to the first port, and transmitted from the second port to the optical transmission line (17). The transmitted optical multiplex signal propagates through the optical transmission line (17) and reaches the other optical transmission / reception device (20 '). The other optical transceiver (20 ')
Multiplexed signal that arrives at the three-terminal circulator (1
5 ') through the second and third ports, the optical demultiplexer (14').
). Then, from the optical demultiplexer 14 ', the first
The optical signal of the wavelength (λ1) and the optical signal of the second wavelength (λ2) are output, and the former is input to the optical receiver (12a ′) and the latter is input to the optical receiver (12a ′). . Optical multiplex transmission using two wavelengths in opposite directions is performed in the same manner as described above.
In other words, one optical transmission line (1
7) Optical bidirectional multiplex transmission can be performed.

Here, the wavelengths (λ1 and λ2) of two optical signals multiplexed and transmitted in the forward direction and the wavelengths (λ1 ′ and λ2 ′) of two optical signals multiplexed and transmitted in the backward direction are as follows.
Typically, they are the same (λ1 = λ1 ′ and λ2 = λ2 ′) as in the second invention described below, but may be different from each other.

According to a second aspect, in the first aspect, the wavelengths (λ1 and λ) of the two optical signals multiplex-transmitted in the forward direction are provided.
2) and the wavelengths (λ1 ′ and λ2 ′) of two optical signals multiplex-transmitted in the opposite direction are the same.

In the second aspect, bidirectional optical multiplex transmission can be performed through one optical transmission line (17) using only two types of wavelengths.

According to a third aspect, in the second aspect, a plurality of pairs of optical transmission / reception devices (20 and 20 ') are provided, and the plurality of pairs of optical transmission / reception devices multiplex two optical signals to form a pair. It is characterized in that the operations for transmitting data in the two directions are executed in parallel.

In the third aspect of the present invention, a plurality of optical bidirectional multiplex transmissions through one optical transmission line with two wavelengths are performed in parallel with each other, so that optical bidirectional multiplex transmission can be performed at a high transmission rate. become. For example, if two bidirectional optical multiplex transmissions are performed in parallel (that is, if two optical bidirectional optical multiplex transmission systems are provided in parallel), a conventional bidirectional optical multiplex transmission system using four wavelengths ( The same transmission rate as that of FIG. 10) (four times that in the case of transmission with a single wavelength) is realized. Also, if three are executed in parallel, a transmission rate 1.5 times higher than the conventional one is realized, and if four are executed in parallel, a transmission rate twice as high as the conventional one is realized. That is, the number of parallels is doubled,
By increasing the transmission rate by a factor of three,.
The speed can be increased as shown in FIG. In other words, the number of types of wavelengths used for transmission is always only two, regardless of the transmission rate to be achieved. Therefore, unlike the conventional case, there is no need to prepare many types of light sources, and high accuracy There is no need to perform wavelength control. Therefore, it is possible to suppress the increase in the price of the system due to the increase in the transmission rate less than in the conventional case.

In the first aspect of the present invention, as described above, an increase in the price of the system due to an increase in the transmission rate can be suppressed, but there are the following problems. For example, the first
The optical bidirectional transmission of the video signal is performed using the optical transmitter (11a) and the second optical receiver (12b), and the second optical transmitter (11b) and the first optical receiver (12a). In the case of considering an application such as performing optical bidirectional transmission of a data signal by using the above, there is a case where a place for transmitting and receiving a video signal and a place for transmitting and receiving a data signal are separated from each other. In such a case, the optical transmission path (16a) between the first optical transmission section (11a) and the optical multiplexing section (13), the second optical reception section (12b) and the optical demultiplexing section (14) Optical transmission line (1)
6d) to extend the two optical transmission lines, or
An optical transmission path (16b) between the optical transmitting section (11b) and the optical multiplexing section (13), and an optical transmission path between the first optical receiving section (12a) and the optical demultiplexing section (14) The two optical transmission paths with (16c) must be extended. The second invention described below solves this problem.

A fourth invention is an optical bidirectional multiplex transmission system (FIG. 2) for multiplexing two optical signals having mutually different wavelengths and transmitting the multiplexed signals in both directions. 30 ′), and each optical transceiver (3
0) are mutually different wavelengths (λ1 and λ2)
First and second for transmitting two optical signals having
Optical transmission units (21a and 21b) having two input / output terminals and one multiplexed input / output terminal, and multiplex and output two optical signals having different wavelengths to be input, and An optical bidirectional multiplexer / demultiplexer (28) for demultiplexing an input optical multiplexed signal into two optical signals having different wavelengths and outputting the resulting signals, using different wavelengths (λ1 ′ and λ
2 ′), the first and second optical receivers (22a and 22b) for receiving two optical signals, the optical signal input to the input terminal is output from the input / output terminal, and the input / output terminal A pair of optical demultiplexers (23 and 24) for outputting an input optical signal from an output terminal; and an optical signal input to a first port is output from a second port and input to a second port. An optical signal is output from the third port, and
The optical signal input to the port is output from the fourth port,
And a four-terminal circulator (25) for outputting an optical signal input to the fourth port from the first port, and an optical bidirectional multiplexer / demultiplexer (28) provided in each optical transceiver.
Are connected to each other via an optical transmission line (27), and in each optical transceiver, the input end of one optical demultiplexer (23) is connected to the first optical transmission unit (21a). Connected, and the input / output end of the optical demultiplexer (23) is connected to the first port of the four-terminal circulator (25), and the output end of the optical demultiplexer (23) is connected to the first optical receiver. (22
a), the input end of the other optical splitter (24) is connected to the second optical transmitter (21b), and the input / output end of the optical splitter (24) is a four-terminal circulator ( 25), the output end of the optical demultiplexer (24) is connected to the second optical receiver (22b), and the second and fourth ports of the four-terminal circulator (25) are connected to the third port. It is characterized in that it is connected to two input / output terminals of the optical bidirectional multiplex / demultiplexer (28).

In the fourth aspect, optical multiplex transmission using two wavelengths in the forward direction is performed as follows. A first optical transmission unit (21a) in one of the optical transmission / reception devices (30);
An optical signal of the first wavelength (λ1) transmitted from the optical splitter (23) passes through the input terminal and the input / output terminal of one of the optical demultiplexers (23) and the first and second ports of the four-terminal circulator (25). The signal is input to one input / output terminal of the bidirectional multiplex demultiplexer (28). The optical signal of the second wavelength (λ2) transmitted from the second optical transmitter (21b) is transmitted to the other optical demultiplexer (24).
Input terminal, input / output terminal, and four-terminal circulator (2
The signal is input to the other input / output terminal of the optical bidirectional multiplexing / demultiplexing device (28) through the third and fourth ports 5). Then, optical multiplexed signals (wavelengths λ1 and λ2) are transmitted to the optical transmission line (27) from the multiplex input / output terminal of the optical bidirectional multiplexing / demultiplexing device (28). The transmitted optical multiplex signal propagates through the optical transmission line (27) and reaches the other optical transmission / reception device (30 ').

The optical multiplexed signal arriving at the other optical transmitting / receiving device (30 ') is input to the multiplexed input / output terminal of the optical bidirectional multiplexing / demultiplexing device (28'), and the first input / output terminal of the multiplexed input / output terminal. The optical signal of the wavelength (λ1) is output from the other input / output terminal, and the optical signal of the second wavelength (λ2) is output from the other input / output terminal. The optical signal of the first wavelength (λ1) passes through the second and third ports of the four-terminal circulator (25 ′) and the input / output terminal and output terminal of the other optical demultiplexer (24 ′). To the optical receiver (22b '). On the other hand, the second wavelength (λ2)
Of the four-terminal circulator (25 ')
The light is input to the first optical receiver (22a ') through the first port and the input / output terminal and output terminal of one of the optical demultiplexers (23'). Optical multiplex transmission using two wavelengths in opposite directions is performed in the same manner as described above. That is, the first optical bidirectional multiplex transmission system (29 ₁ ) can perform optical bidirectional multiplex transmission through one optical transmission line (27) using two wavelengths in the forward and reverse directions.

In this manner, bidirectional optical multiplex transmission can be performed through one optical transmission line (27), as in the first invention. Further, unlike the first invention, when the place for transmitting / receiving a video signal and the place for transmitting / receiving a data signal are separated from each other, only one optical transmission line, that is, a pair of optical demultiplexers is used. (23 and 24) and a four-terminal circulator (2
It is only necessary to extend one of the two optical transmission lines (26e and 26f) to 5). In this case, the number of optical transmission components such as optical fibers and optical connectors can be reduced, and as a result, the reliability of the entire system can be improved and the cost can be reduced.

In a fifth aspect based on the fourth aspect, the wavelengths (λ1 and λ) of the two optical signals multiplex-transmitted in the forward direction are provided.
2) and the wavelengths (λ1 ′ and λ2 ′) of two optical signals multiplex-transmitted in the opposite direction are the same.

According to the fifth aspect, the same effect as that of the second aspect can be obtained.

In a sixth aspect based on the fifth aspect, a plurality of pairs of optical transmission / reception devices (30 and 30 ') are provided, and the plurality of pairs of optical transmission / reception devices multiplex two optical signals to form a pair. It is characterized in that the operations for transmitting data in the two directions are executed in parallel.

According to the sixth aspect, the same effects as those of the third aspect can be obtained.

According to a seventh aspect of the present invention, there is provided an optical signal having a first wavelength (λ1) and a second wavelength (λ) different from the first wavelength.
2) combining the optical signal with the optical signal having 2) and / or
An optical module (FIGS. 3 to 6) for demultiplexing an input optical multiplex signal into an optical signal having the first wavelength and an optical signal having the second wavelength. An optical filter provided substantially at right angles to the waveguide substrate (35) and the main plane (35a) of the optical waveguide substrate, for transmitting an optical signal having a first wavelength and reflecting an optical signal having a second wavelength; (34) and first to sixth optical waveguides (33a to 33f) extending from one point on the optical filter in the direction of the outer peripheral end surfaces (31, 32) along the main plane of the optical waveguide substrate. No. 1 optical waveguide (33a) is an optical filter and θ1
And the second optical waveguide (33b) is on an extension of the first optical waveguide, and the third optical waveguide (33c)
Makes an angle of (180 ° −θ1) with the optical filter,
The fourth optical waveguide (33d) forms an angle of θ2 with the optical filter, the fifth optical waveguide (33e) is on an extension of the fourth optical waveguide, and the sixth optical waveguide (33f) is The optical filter is characterized by forming an angle of (180 ° −θ2) with the optical filter.

The optical module according to the seventh aspect of the present invention provides an optical signal (wavelength λ) input to the fifth optical waveguide (33e).
1) and an optical signal (wavelength λ2) input to the sixth optical waveguide (33f) are multiplexed with each other, and the obtained optical multiplexed signal (wavelengths λ1, λ2) is added to the fourth optical waveguide (33). ), And demultiplexes an optical multiplexed signal (wavelengths λ1, λ2) input to the first optical waveguide (33a), and obtains one of the obtained optical signals (wavelength λ1) in the second optical waveguide. From the wave path (33b)
The other optical signal (wavelength λ2) is transmitted to a third optical waveguide (33c).
Has the effect of outputting each. Therefore, as in the eighth invention described below, the optical multiplexer (13) and the optical demultiplexer (14) included in the optical transmission and reception device (20) in the second and third inventions are replaced by the optical multiplexer (13). The optical module according to the present invention can be integrally configured.

In the optical module according to the seventh aspect, the optical signal (wavelength λ1) input to the fifth optical waveguide (33e) is output from the fourth optical waveguide (33d). The optical signal (wavelength λ2) input to the fourth optical waveguide (33d) is output from the sixth optical waveguide (33f), and the optical signal (wavelength λ1) is input to the second optical waveguide (33b). Is output from the first optical waveguide (33a), and an optical signal (wavelength λ2) input to the first optical waveguide (33a) is output from the third optical waveguide (33c). Therefore, like the ninth invention described below, the pair of optical demultiplexers (23 and 24) included in the optical transmission / reception device (30) in the fifth and sixth inventions are related to the seventh invention. The optical module can be integrally configured.

In an eighth aspect based on the second or third aspect, the optical multiplexer (13) and the optical demultiplexer (14) are integrally formed by the optical module according to the seventh aspect.

In a ninth aspect based on the fifth or sixth aspect, the pair of optical demultiplexers (23 and 24) is integrally formed by the optical module according to the seventh aspect.

The eighth and ninth aspects of the invention (or the following first aspect)
In the fourth, fifteenth, seventeenth, and eighteenth inventions), the number of components can be reduced. Further, since the optical filter (34) and the like are particularly expensive, if two optical filters (34) having substantially the same area as those constituting one optical duplexer can be constituted, the cost of parts can be greatly reduced. Becomes possible.

In a tenth aspect based on the seventh aspect, the first optical waveguide includes a first optical transmission line (37a) for transmitting an optical multiplexed signal to be demultiplexed by the optical filter. A first light receiving element (3) for receiving an optical signal having a first wavelength obtained by splitting an optical filter is provided in the optical waveguide of (3).
6a) is a third optical waveguide, and a second light receiving element (36b) for receiving an optical signal having a second wavelength obtained by splitting the optical filter is provided in the fifth optical waveguide. The first light-emitting element (36c) for transmitting an optical signal having the first wavelength to be multiplexed by the optical filter has a first light-emitting element (36c), and the sixth optical waveguide has an optical filter to be multiplexed. A second light emitting element (3) for transmitting an optical signal having a second wavelength;
6d) is a second optical transmission line (37) for transmitting an optical multiplexed signal obtained by multiplexing an optical filter in the fourth optical waveguide.
b) are optically coupled to each other on the outer peripheral surface of the optical waveguide substrate.

In the tenth aspect, an optical element is coupled to each optical waveguide.

According to an eleventh aspect based on the second or third aspect, the first optical transmission section (11a), the second optical transmission section (11b), the optical multiplexer (13), and the optical demultiplexer ( 14), a first optical receiver (12a) and a second optical receiver (12a).
b) is integrally formed by the optical module according to the tenth aspect.

According to a twelfth aspect, in the fifth or sixth aspect, a first optical transmission section (21a), a second optical transmission section (21b), a pair of optical demultiplexers (23 and 24), First
Optical receiving section (22a) and second optical receiving section (22b)
Are integrally configured by the optical module according to the tenth aspect.

According to the eleventh and twelfth aspects, the optical waveguides 33b, 33c, 33e and 33f and the optical transceiver 3
There is no need to provide an optical fiber between 6a-36d,
Further component reduction is possible.

According to a thirteenth aspect, an optical signal having a first wavelength (λ1) and an optical signal having a second wavelength (λ2) different from the first wavelength are multiplexed with each other and / or An optical module (FIG. 7) for demultiplexing an input optical multiplexed signal into an optical signal having the first wavelength and an optical signal having the second wavelength. 6, an optical fiber (42a to 42f), a lens (41), an optical filter (43) that transmits an optical signal having a first wavelength and reflects an optical signal having a second wavelength, and a mirror ( 44) wherein the optical filter is disposed at one focal position of the lens at right angles to the optical axis of the lens;
In the first to sixth optical fibers, the end face centers of the first to sixth optical fibers are arranged in a line and at equal intervals in this order, and the end face centers of the second optical fiber and the third The mirror is provided such that the midpoint with the center of the end face of the optical fiber is located at the other focal position of the lens, and the mirror is provided in the vicinity of the optical filter and on the opposite side to the lens with respect to the optical filter. It is provided with an angle inclination, the inclination angle is,
The angle is such that the optical signal having the first wavelength emitted from the end face of the first optical fiber is reflected and made incident on the end face of the sixth optical fiber.

The optical module according to the thirteenth invention is characterized in that:
An optical signal (wavelength λ1) input to the fifth optical fiber (42e) and an optical signal (wavelength λ2) input to the third optical fiber (42c) are multiplexed with each other to obtain light. The multiplexed signal (wavelengths λ1, λ2) is transmitted to a second optical fiber (42b).
And splits an optical multiplexed signal (wavelengths λ1 and λ2) input to the first optical fiber (42a) and converts one of the obtained optical signals (wavelength λ1) to a sixth optical fiber (4
2f), the other optical signal (wavelength λ2) is output from the fourth optical fiber (42d).
Therefore, as in a fourteenth aspect described below, the optical multiplexer (13) and the optical demultiplexer (14) included in the optical transmission / reception device (20) in the second and third aspects are replaced by the thirteenth aspect. The optical module according to the present invention can be integrally configured.

Further, in the optical module according to the thirteenth aspect, the optical signal (wavelength λ1) input to the fifth optical fiber (42e) is output from the second optical fiber (42b), and An optical signal (wavelength λ2) input to the second optical fiber (42b) is output from the third optical fiber (42c), and an optical signal (wavelength λ1) input to the sixth optical fiber (42f). Is output from the first optical fiber (42a), and the optical signal (wavelength λ2) input to the first optical fiber (42a) is output from the fourth optical fiber (42d). Therefore, as in the fifteenth invention described below, the optical transmission and reception device (3
A pair of optical demultiplexers (23 and 24) included in 0)
Can be integrally configured by the optical module according to the thirteenth invention.

In a fourteenth aspect based on the second or third aspect, the optical multiplexer (13) and the optical demultiplexer (14) are
The optical module according to the thirteenth invention is integrally formed.

According to a fifteenth aspect, in the fifth or sixth aspect, the pair of optical demultiplexers (23 and 24) is a thirteenth aspect.
The optical module according to the present invention is integrally configured.

According to a sixteenth aspect, an optical signal having a first wavelength (λ1) and an optical signal having a second wavelength (λ2) different from the first wavelength are multiplexed with each other, and / or An optical module (FIG. 10) for demultiplexing an input optical multiplexed signal into an optical signal having the first wavelength and an optical signal having the second wavelength. 7, an optical fiber (52a to 52g), a lens (51),
An optical filter (53) that transmits an optical signal having a first wavelength and reflects an optical signal having a second wavelength, and a mirror (54), wherein the optical filter is located at one focal position of the lens. The first to seventh optical fibers are arranged at right angles to the optical axis of the lens, and the second to seventh optical fibers are in close contact with each other around the first optical fiber in this order. And the midpoint between the center of the end face of the first optical fiber and the center of the end face of the third optical fiber,
The mirror is provided so as to be at the other focal position of the lens, and the mirror is provided at a predetermined angle with respect to the optical filter near the optical filter and on the side opposite to the lens, and the tilt angle is The angle is such that an optical signal having the first wavelength emitted from the end face of the third optical fiber is reflected and made incident on the end face of the sixth optical fiber.

The optical module according to the sixteenth aspect of the present invention comprises:
An optical signal (wavelength λ1) input to the fifth optical fiber (52e) and an optical signal (wavelength λ2) input to the third optical fiber (52c) are multiplexed with each other to obtain light. The multiplexed signal (wavelengths λ1, λ2) is transmitted to a second optical fiber (52b).
And splits an optical multiplexed signal (wavelengths λ1 and λ2) input to the first optical fiber (52a) and converts one of the obtained optical signals (wavelength λ1) to a sixth optical fiber (5
2f), the other optical signal (wavelength λ2) is output from the fourth optical fiber (52d).
Therefore, as in the following seventeenth aspect, the optical multiplexer (13) and the optical demultiplexer (14) included in the optical transceiver (20) in the second and third aspects are replaced by the sixteenth aspect. The optical module according to the present invention can be integrally configured.

Also, in the optical module according to the sixteenth aspect, the optical signal (wavelength λ1) input to the fifth optical fiber (52e) is output from the second optical fiber (52b). An optical signal (wavelength λ2) input to the second optical fiber (52b) is output from the third optical fiber (52c), and an optical signal (wavelength λ1) input to the sixth optical fiber (52f). Is output from the first optical fiber (52a), and the optical signal (wavelength λ2) input to the first optical fiber (52a) is output from the fourth optical fiber (52d). Therefore, as in the following eighteenth aspect, in the fifth and sixth aspects, the optical transceiver (3
A pair of optical demultiplexers (23 and 24) included in 0)
Can be integrally configured by the optical module according to the sixteenth aspect.

According to a seventeenth aspect, in the second or third aspect, the optical multiplexer (13) and the optical demultiplexer (14) are:
The optical module according to the sixteenth aspect is integrally formed.

According to an eighteenth aspect based on the fifth or sixth aspect, the pair of optical demultiplexers (23 and 24) is a sixteenth aspect.
The optical module according to the present invention is integrally configured.

The nineteenth invention is directed to an optical bidirectional multiplex transmission / reception apparatus (20) for multiplexing two optical signals having different wavelengths and transmitting the signals in both directions, wherein the wavelengths (λ1 and λ2) are different from each other. ) Having two input terminals and one output terminal, and having different input wavelengths. An optical multiplexer (13) for multiplexing and outputting two optical signals with each other, having one input terminal and two output terminals, and converting an input optical multiplexed signal into two optical signals having different wavelengths; The optical demultiplexer (14) for demultiplexing the signal into a signal and outputting the signal has different wavelengths (λ
1 ′ and λ2 ′) for receiving the two optical signals having the first and second optical receivers (12a and 12a).
b) and an optical signal input to the first port is output from the second port, and an optical signal input to the second port is output from the third port.
5), the second port of the three-terminal circulator (15) is connected to the optical transmission line (17), and the first and second optical transmitters (11a and 11b) are connected to the two of the optical multiplexer (13).
And an output end of the optical multiplexer (13) is connected to a first port of the three-terminal circulator (15).
A third port of the three-terminal circulator (15) is connected to an input end of the optical splitter (14), and two output ends of the optical splitter (14) are connected to the first and second optical receivers (12a and 12a). 1
2b).

The nineteenth invention corresponds to the optical transmission / reception device (20) provided in the optical bidirectional multiplex transmission / reception system according to the first invention.

A twentieth aspect of the present invention is an optical bidirectional multiplex transmission / reception device (30) for multiplexing two optical signals having different wavelengths and transmitting the signals in both directions, wherein the wavelengths (λ1 and λ2 ) Having two input / output terminals and one multiplexed input / output terminal, which are different from each other. An optical bidirectional multiplexing / demultiplexing device that multiplexes two optical signals having wavelengths and outputs the multiplexed signal, and demultiplexes an input optical multiplexed signal into two optical signals having different wavelengths and outputs the resultant signal. 28), first and second optical receivers (22a and 22b) for receiving two optical signals having different wavelengths (λ1 ′ and λ2 ′), and input / output optical signals input to input terminals. Output from the end and in and out A pair of optical demultiplexers (23 and 24) for outputting an optical signal input to an end from an output end, and an optical signal input to a first port is output from a second port and input to a second port Four terminals from which the output optical signal is output from the third port, the optical signal input to the third port is output from the fourth port, and the optical signal input to the fourth port is output from the first port A circulator (25), a multiplexed input / output terminal of an optical bidirectional multiplexing / demultiplexing device (28) is connected to an optical transmission line (27), and an input terminal of one of the optical demultiplexing devices (23) is a first optical multiplexing device; The input / output terminal of the optical demultiplexer (23) is connected to the first port of the four-terminal circulator (25), and the output terminal of the optical demultiplexer (23) is connected to the transmitting unit (21a). The first optical receiver (22)
a), the input end of the other optical splitter (24) is connected to the second optical transmitter (21b), and the input / output end of the optical splitter (24) is a four-terminal circulator ( 25), the output end of the optical demultiplexer (24) is connected to the second optical receiver (22b), and the second and fourth ports of the four-terminal circulator (25) are connected to the third port. It is characterized in that it is connected to two input / output terminals of the optical bidirectional multiplex / demultiplexer (28).

The twentieth aspect of the present invention corresponds to the optical transmission / reception device (30) provided in the optical bidirectional multiplex transmission / reception system according to the fourth aspect of the invention.

[0050]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of an optical bidirectional multiplex transmission system according to a first embodiment of the present invention. In FIG. 1, the optical bidirectional multiplex transmission system includes:
First to n-th optical bidirectional multiplex transmission systems 18 ₁ to 18 _n (where n is an integer of 1 or more; the same applies hereinafter).

The first optical bidirectional multiplex transmission system ₁₈₁ includes a pair of optical transmitting and receiving device 20 and 20 'which are connected to each other via the optical transmission path 17. The optical transmitting / receiving device 20 includes two optical transmitting units 11a and 11b and two optical receiving units 12a.
And 12b, an optical multiplexer 13, an optical demultiplexer 14, and a three-terminal circulator 15. Optical transceiver 20 '
Are two optical transmitting units 11a ′ and 11b ′, two optical receiving units 12a ′ and 12b ′, and an optical multiplexer 13 ′.
And a three-terminal circulator 15 '.

In the optical transmitting / receiving apparatus 20, the optical transmitting units 11a and 11b transmit two optical signals having different wavelengths (these wavelengths are λ1 and λ2). The optical multiplexer 13 has two input terminals and one output terminal, and multiplexes two input optical signals having different wavelengths (λ1 and λ2) and outputs them. The optical demultiplexer 14 has one input terminal and two output terminals, and converts the input optical multiplexed signal into different wavelengths (these are the optical transmitting units 11a 'and 1' on the transmitting / receiving device 20 'side).
1b ′ is the wavelength of the optical signal to be transmitted, λ1 ′ and λ
2 ′) and output after demultiplexing into two optical signals. The optical receivers 12a and 12b receive two optical signals having different wavelengths (λ1 ′ and λ2 ′). The three-terminal circulator 15 has first to third three ports (indicated by 〜 in the figure), outputs an optical signal input to the first port from the second port, and outputs the optical signal to the second port. The input optical signal is output from the third port.

The optical transmitters 11 a and 11 b are connected to the two input terminals of the optical multiplexer 13, the output terminal of the optical multiplexer 13 is connected to the first port of the three-terminal circulator 15, The third port is connected to an input terminal of the optical demultiplexer 14, and two output terminals of the optical demultiplexer 14 are connected to the optical receiving units 12a and 12b.

The optical transmission / reception device 20 'has the same configuration as described above, and the second ports of the three-terminal circulators 15 and 15' included in the optical transmission / reception devices 20 and 20 'are connected via the optical transmission line 17. Connected to each other. Here, λ1 and λ2 and λ1 ′ and λ2 ′ typically have the same value, respectively (that is, λ1 = λ
1 ′ and λ2 = λ2 ′) are not necessarily the same value.

In the first optical bidirectional multiplex transmission system 18 ₁ configured as described above, the forward (ie, from the optical transceiver 20 to the optical transceiver 20 ′) 2 in the forward direction is as follows.
Optical multiplex transmission by wavelength is performed. In the optical transmitting / receiving device 20, an optical signal of wavelength λ1 transmitted from the optical transmitting unit 11a and an optical signal of wavelength λ2 transmitted from the optical transmitting unit 11b are input to the optical multiplexing unit 13, and the optical signal is transmitted from the optical multiplexing unit 13. Multiplexed signals (wavelengths λ1 and λ2) are output. This optical multiplexed signal is input to a first port of the three-terminal circulator 15, and sent out from the second port to the optical transmission line 17. The transmitted optical multiplex signal propagates through the optical transmission line 17 and reaches the optical transmitting / receiving device 20 '.

The optical multiplexed signal arriving at the optical transceiver 20 'is input to the optical demultiplexer 14' through the second and third ports of the three-terminal circulator 15 '. Then, an optical signal of wavelength λ1 and an optical signal of wavelength λ2 are output from the optical demultiplexer 14 ′, and the former is input to the optical receiver (12a ′), and the latter is input to the optical receiver (12a ′). Is done.

Optical multiplex transmission using two wavelengths in the opposite direction (ie, from the optical transceiver 20 'to the optical transceiver 20) is also performed as follows.
This is performed in the same manner as described above. That is, the first optical bidirectional multiplex transmission system ₁₈₁ is a single optical transmission path using two wavelengths (1
7) Optical bidirectional multiplex transmission can be performed.

The _second to n-th optical bidirectional multiplex transmission systems 18 ₂ to 18 ₂
18 _n has the same configuration as the first optical bidirectional multiplex transmission system 18 ₁ , and performs optical bidirectional multiplex transmission with the same two wavelengths. For example, when n is 2, the second bidirectional optical multiplex transmission system 18 ₂ performs the same operation as described above, whereby the present optical bidirectional multiplex transmission system, only using two wavelengths, four Can be transmitted at the same speed as that of the conventional optical bidirectional multiplex transmission system using the wavelength (see FIG. 11).

Further, if the number of optical bidirectional multiplex transmission systems 18 (ie, n) is increased to 3, 4,..., The present optical bidirectional multiplex transmission system uses only two types of wavelengths. 1.5 times the conventional optical bidirectional multiplex transmission system, 2 times
The transmission can be performed at the speed of twice,.

Hereinafter, the optical bidirectional multiplex transmission system in the case where n is 2 will be described more specifically. The light transmitting units 11a and 11b included in the light transmitting unit 20 are configured by, for example, a semiconductor laser and a driving circuit, as in the conventional example. The optical transmission unit 11a transmits a signal using light having a wavelength λ1, and the optical transmission unit 1b transmits a signal using light having a wavelength λ2.

Each of the light receiving sections 12a and 12b includes a light receiving element, and converts a received optical signal into an electric signal. The optical multiplexer 13 is, for example, an optical filter having a wavelength of λ1.
And has the property of transmitting light of wavelength .lambda.2 and two light signals transmitted from the optical receivers 11a and 11b and transmitted through the two optical transmission lines 16a and 16b. The optical signal having the wavelength λ1 and the optical signal having the wavelength λ2 are multiplexed with each other and output to one optical transmission line 16e.

On the other hand, the optical demultiplexer 14 multiplexes the optical multiplexed signal transmitted through one optical transmission line 16f—the optical signal of two kinds of wavelengths λ1 ′ and λ2 ′, contrary to the optical multiplexer 13. Is divided into an optical signal having a wavelength of λ1 ′ and an optical signal having a wavelength of λ2 ′ to obtain two optical transmission lines 16c and 16c.
Output to d. However, in general, the optical multiplexer 13 and the optical demultiplexer 14 can be shared by components having exactly the same structure.

The three-terminal circulator 15 is connected to the optical transmission line 1.
It has the function of outputting the optical signal input from 6e to the optical transmission path 17 and outputting the optical signal input from the optical transmission path 17 to the optical transmission path 16f. As described above, the optical transmission / reception device 20 having one input / output port connected to the optical transmission line 17—the second port () of the three-terminal circulator 15 corresponds thereto—is configured. The optical transmission / reception device 2 having exactly the same configuration as the optical transmission / reception device 20
0 'and, by connecting to each other via the optical transmission path 17, the first optical bidirectional multiplex transmission system ₁₈₁ is realized, further, an optical bidirectional multiplex transmission system 18 ₁ in the first, quite A second optical bidirectional multiplex transmission system 18 _{2 having the} same configuration
Are arranged in parallel, the optical transmission system of the present invention (where n = 2) is realized. Here, λ1 and λ1 ′ may be the same wavelength, or may be different wavelengths. Both λ2 and λ2 ′ may have the same wavelength or different wavelengths.

Next, the operation of the optical transmission system configured as described above will be described. First, two optical signals modulated at predetermined transmission rates by the optical transmitting units 11a and 11b of the optical transmitting and receiving device 20, that is, the optical signal of the wavelength λ1 and the optical signal of the wavelength λ2 are wavelength-multiplexed by the optical multiplexer 13, Output to the optical transmission path 16e. This optical multiplex signal is transmitted to the circulator 15 through the optical transmission line 16e.
Of the optical transmission line 17 from the second port.
Is output to

The optical signal transmitted from the optical transmission / reception device 20 is transmitted through the optical transmission line 17 and then transmitted to the optical transmission / reception device 2.
Reaches 0 '. In the optical transceiver 20 ', the optical multiplexed signal input to the second port of the optical circulator 15' is
The light is output from the third port to the optical transmission line 16f '. This optical multiplexed signal is transmitted through the optical transmission line 16f 'to the optical demultiplexer 1.
4 '. The optical demultiplexer 14 'converts the optical multiplexed signal into two signals.
Optical signals, ie, an optical signal of wavelength λ1 and a wavelength λ2
, And output to separate optical transmission lines 16c 'and 16d'. These two optical signals are input to the optical receivers 12a 'and 12b' corresponding to the respective wavelengths via the optical transmission lines 16c 'and 16d' and output as electric signals.

Transmission in the reverse direction, that is, the optical transmission / reception device 2
0 'to the optical transmitting / receiving device 20 is transmitted in the same manner as described above.
This is performed by wavelength multiplexing signals of the different wavelengths λ1 ′ and λ2 ′. In this manner, bidirectional multiplex transmission of two wavelengths can be performed between the optical transceiver 20 and the optical transceiver 20 'through one optical transmission line 17.

[0067] Then, the second optical multiplex transmission system 18 ₂ constructed similarly, by performing the same operation as described above in parallel, through the optical transmission line 17 two, two-way,
In each direction, it is possible to transmit data at a transmission rate four times that in the case where multiplexing is not performed. That is, the same transmission as in the conventional example can be performed.

Further, in the present optical bidirectional multiplex transmission system, as described above, λ1 and λ1 ′ and λ2 and λ2 ′
May have the same wavelength. That is, it is characteristic that transmission can be performed in exactly the same manner as in the conventional example using only two types of wavelengths, λ1 and λ2, as light wavelengths. Thus, quadruple-speed transmission similar to that of the conventional example can be achieved only by providing two types of light sources. In addition, since the difference between the two wavelengths can be made large, it is possible to relax the tolerance of each center wavelength.

For example, λ1 = 1.55 μm, λ2 = 1.3
When the thickness is 1 μm, a semiconductor laser having a very common wavelength used in optical communication can be used, and an optical transmission system can be assembled at a lower cost than before. In addition, since the difference between the wavelengths of λ1 and λ2 is as large as 0.24 μm, the tolerance of each center wavelength is extremely loose, so that control such as temperature control becomes unnecessary.
The optical transmission system can be simplified. As a result, an excellent effect that the reliability of the system is improved and the cost can be reduced can be obtained.

[0070] As described above, in the present embodiment, the first optical bidirectional multiplex transmission system ₁₈₁ is only the (typically using two wavelengths, the forward λ1 and .lambda.2, backwards λ
1 ′ and λ2 ′ are used, in particular, λ1 = λ1 ′ and λ
2 = λ2 ′), and optical bidirectional multiplex transmission through one optical transmission line 17 is performed. Then, the first optical bidirectional multiplex transmission system 18 _1, the second add optical bidirectional multiplex transmission system 18 ₂ having the same configuration and perform the same transmission from one another in parallel in two systems Therefore, transmission can be performed at twice the rate (in the case of performing with one system) without increasing the number of wavelength types. In general, by providing the _first to _n-th optical bidirectional multiplex transmission systems 18 ₁ to 18 _n , only 2
Transmission can be performed at n times the rate using only the types of wavelengths.

In this case, regardless of the transmission rate, only 2
Light sources having different wavelengths may be prepared. In the case of two wavelengths, since the interval between the wavelengths is wide, it is not necessary to perform wavelength control with high accuracy. As a result, an increase in system price due to an increase in transmission rate can be suppressed to a lesser extent than in the past.

As described above, according to the first embodiment of the present invention, the effect that the reliability of the system can be improved and the cost can be reduced can be obtained. Was. In the configuration of FIG. 1, for example, optical bidirectional transmission of a video signal is performed using the optical transmission unit 11a and the optical reception unit 12b, and optical bidirectional transmission of a data signal is performed using the optical transmission unit 11b and the optical reception unit 12a. Consider applications such as transmission. At this time, the place where the video signal is transmitted and received may be separated from the place where the data signal is transmitted and received. In such a case, the two optical transmission lines 16a and 16d are extended. Or 16b and 1
The two optical transmission lines 6c must be extended.

A second embodiment described below discloses an optical bidirectional multiplex transmission system in which the above-mentioned problem is solved. In this system, for example, when a place for transmitting and receiving a video signal and a place for transmitting and receiving a data signal are separated from each other, only one optical transmission line needs to be extended.

(Second Embodiment) FIG. 2 is a block diagram showing a configuration of an optical bidirectional multiplex transmission system according to a second embodiment of the present invention. In FIG. 2, the optical bidirectional multiplex transmission system includes first to n-th optical bidirectional multiplex transmission systems 29 ₁ to 29 2.
9 _n (where n is any integer of 1 or more; the same applies hereinafter).

The first optical bidirectional multiplex transmission system 29 ₁ includes a pair of optical transmission / reception devices 30 and 30 ′ connected to each other via an optical transmission line 27. The optical transmitting and receiving device 30 includes two optical transmitting units 21a and 21b and two optical receiving units 22a.
22b, a pair of optical demultiplexers 23 and 24, a four-terminal circulator 25, and an optical bidirectional multiplex demultiplexer 28. The optical transmitting / receiving device 30 ′ includes two optical transmitting units 21.
a 'and 21b', two optical receivers 22a 'and 12b', a pair of optical demultiplexers 23 'and 24', a four-terminal circulator 25 ', and an optical bidirectional multiplex demultiplexer 2.
8 '.

In the optical transmitting / receiving device 30, the optical transmitting units 21a and 21b transmit two optical signals having different wavelengths (these wavelengths are assumed to be λ1 and λ2). The optical bidirectional multiplexing / demultiplexing device 28 has two input / output terminals and one multiplexed input / output terminal, and receives different wavelengths (λ
1 and .lambda.2) are multiplexed with each other and output, and the input optical multiplexed signal is converted into an optical multiplexed signal having different wavelengths (these optical multiplexed signals are transmitted and received by the optical transmitting unit 21 on the transmitting / receiving apparatus 30 'side).
a ′ and 21b ′ are the wavelengths of the transmitted optical signals, λ
1 ′ and λ2 ′).

The optical receivers 22a and 22b receive two optical signals having different wavelengths (λ1 ′ and λ2 ′). The optical demultiplexers 23 and 24 have three terminals of an input terminal, an input / output terminal, and an output terminal, output an optical signal input to the input terminal from the input / output terminal, and output an optical signal input to the input / output terminal. The signal is output from the output terminal. The four-terminal circulator 25 has first to fourth four ports (indicated by 〜 in the figure), outputs an optical signal input to the first port from the second port, and outputs the optical signal to the second port. The input optical signal is output from the third port, the optical signal input to the third port is output from the fourth port, and the optical signal input to the fourth port is output from the first port.

The input end of one of the optical splitters 23 is connected to the optical transmitting section 21a, and the input / output end of the optical splitter 23 is connected to the first port of the four-terminal circulator 25.
The output end of the optical demultiplexer 23 is connected to the optical receiver 22a. The input end of the other optical splitter 24 is connected to the optical transmitter 21b, and the input / output end of the optical splitter 24 is connected to the third port of the four-terminal circulator 25. Is connected to the optical receiver 22b. Further, the second and fourth ports of the four-terminal circulator 25 are connected to two input / output terminals of the optical bidirectional multiplex / demultiplexer 28.

The optical transmitter / receiver 30 'has the same configuration as that described above, and the multiplexed input / output terminals of the optical bidirectional multiplexers / demultiplexers 28 and 28' included in the optical transmitter / receivers 30 and 30 'are optically connected to each other. They are connected to each other via a transmission line 27. Here, λ1 and λ2 and λ1 ′ and λ2 ′ have the same value (that is, λ1 = λ1 ′ and λ2 =
λ2 '). However, they need not be exactly the same value.

In the first optical bidirectional multiplex transmission system 29 ₁ configured as described above, the forward (that is, from the optical transceiver 30 to the optical transceiver 30) 2
Optical multiplex transmission by wavelength is performed. In the optical transmission / reception device 30, the optical signal of the wavelength λ1 transmitted from the optical transmission unit 21a is transmitted through the input terminal, the input / output terminal of the optical demultiplexer 23, and the first and second ports of the four-terminal circulator 25 to both the optical signals. It is input to one of the input / output terminals of the directional demultiplexer 28. The optical signal of the wavelength λ2 transmitted from the optical transmission unit 21b is transmitted through the input terminal, the input / output terminal of the optical demultiplexer 24, and the third and fourth ports of the four-terminal circulator 25 to perform bidirectional multiplex demultiplexing. The signal is input to the other input / output terminal of the device 28. Then, optical multiplexed signals (wavelengths λ1 and λ2) are transmitted to the optical transmission line 27 from the multiplex input / output terminal of the optical bidirectional multiplexing / demultiplexing device. The transmitted optical multiplex signal propagates through the optical transmission line 27 and reaches the optical transmitting / receiving device 30 '.

The optical multiplexed signal arriving at the optical transmitting / receiving device 30 'is input to the multiplexed input / output terminal of the optical bidirectional multiplexing / demultiplexing device 28'. Optical signals of wavelength λ2 are output from the input / output terminals. The optical signal having the wavelength λ1 is input to the optical receiving unit 22b ′ through the second and third ports of the four-terminal circulator 25 ′ and the input / output terminal and the output terminal of the optical demultiplexer 24 ′. On the other hand, the optical signal having the wavelength λ2 is input to the optical receiver 22a 'through the fourth and first ports of the four-terminal circulator 25' and the input / output terminal and output terminal of the optical demultiplexer 23 '.

The optical multiplex transmission using two wavelengths in the opposite direction (ie, from the optical transceiver 30 'to the optical transceiver 30) is also performed as follows.
This is performed in the same manner as above. That is, the first optical bidirectional multiplex transmission system 29 ₁ can perform optical bidirectional multiplex transmission through one optical transmission line (27) using two wavelengths in the forward and reverse directions.

The _second to n-th optical bidirectional multiplex transmission systems 29 ₂ to 29 ₂
29 _n also first have a bidirectional optical multiplex transmission system 29 ₁ same configuration as, and perform the same operation. For example, when n is 2, the second bidirectional optical multiplex transmission system 29 ₂ performs the same operation as described above, whereby the present optical bidirectional multiplex transmission system, only using two wavelengths, four The transmission can be performed at the same speed as that of the conventional optical bidirectional multiplex transmission system using the wavelength (see FIG. 10).

Further, if the number of optical bidirectional multiplex transmission systems 29 (ie, n) is increased to 3, 4,..., This optical bidirectional multiplex transmission system uses only two types of wavelengths. 1.5 times the conventional optical bidirectional multiplex transmission system, 2 times
The transmission can be performed at the speed of twice,.

Hereinafter, the optical bidirectional multiplex transmission system in the case where n is 2 will be described more specifically. The light transmitting units 21a and 21b included in the light transmitting unit 30 are configured by, for example, a semiconductor laser and a driving circuit, as in the conventional example. The optical transmitting unit 21a transmits a signal to the optical transmission line 26a using light of the wavelength λ1, and the optical transmitting unit 21b transmits a signal to the optical transmission line 26c using light of the wavelength λ2.

The light receiving units 22a and 22b each include a light receiving element, and convert an optical signal transmitted through the optical transmission lines 26b and 26d into an electric signal. Where λ1 and λ
1 'is a different symbol for convenience of description, but has the same or almost the same wavelength. Both λ2 and λ2 'have the same or almost the same wavelength.

The optical demultiplexer 23 outputs the optical signal (λ1) input from the optical transmission line 26a to the optical transmission line 26e, and outputs the optical signal (λ2 ′) input from the optical transmission line 26e to the optical transmission line. 26b. The optical splitter 24 is
The optical signal (λ2) input from the optical transmission line 26c is output to the optical transmission line 26f, and the optical signal (λ1 ′) input from the optical transmission line 26f is output to the optical transmission line 26d. . In addition, the optical splitter 23 and the optical splitter 24 can be configured by components having exactly the same structure.

The four-terminal circulator 25 is connected to the optical transmission line 2
The optical signal (λ1) input from the optical transmission line 26g is output to the optical transmission line 26g, and the optical signal (λ1 ′) input from the optical transmission line 26g is output.
) Is output to the optical transmission path 26f, the optical signal (λ2) input from the optical transmission path 26f is output to the optical transmission path 26h, and the optical signal (λ2 ′) input from the optical transmission path 26h is output to the optical transmission path. 26e.

The optical bidirectional multiplexing / demultiplexing device 28 is
a and 21b, and transmitted through the optical transmission lines 26a and 26b, the optical transmission lines 26e and 26f, and the optical transmission lines 26g and 26h—an optical signal having a wavelength of λ1 and an optical signal having a wavelength of λ2 Are multiplexed with each other and output to the optical transmission line 17. The optical bidirectional multiplexing / demultiplexing device 28 can also be constituted by components having exactly the same structure as the optical demultiplexing devices 23 and 24.

As described above, the optical transmission / reception device 30 having one input / output port connected to the optical transmission line 27—the multiplexed input / output end of the optical bidirectional multiplexing / demultiplexing device 28 corresponds to this.
It constitutes. Then, the optical transceiver 30
And an optical transmission / reception device 30 ′ having the same configuration are connected to each other via an optical transmission line 27, thereby forming a _first optical bidirectional multiplex transmission system 291. a counter multiplexing transmission system 29 _1, if at all parallel to each other the second and bidirectional optical multiplex transmission system 29 ₂ of the same configuration,
This optical transmission system (where n = 2) is realized.

Next, the operation of the optical transmission system configured as described above will be described. First, two optical signals modulated at a predetermined transmission rate by the optical transmitting units 21a and 21b of the optical transmitting and receiving device 30, that is, the optical signal of the wavelength λ1 and the optical signal of the wavelength λ2 are respectively transmitted to the optical multiplexer 2
The light is output to the optical transmission lines 26e and 26f through the transmission lines 3 and 24. These optical signals are input to the first and third ports of the four-terminal circulator 25 through the optical transmission lines 26e and 26, and are transmitted from the second and fourth ports to the optical transmission lines 26g and 26h.
Is output to Then, it is wavelength-multiplexed by the optical bidirectional multiplex / demultiplexer 28 and output to the optical transmission line 27.

The optical multiplexed signal transmitted from the optical transmission / reception device 20 (that is, the optical signal having the wavelength λ1 and the wavelength λ2
The optical signal of FIG. 1) passes through the optical transmission line 17 and reaches the optical transmitting / receiving device 20 ′. In the optical transmitting / receiving device 20 ', the optical bidirectional multiplexing / demultiplexing device 28' receives the optical multiplexed signal and demultiplexes it into an optical signal having a wavelength λ1 and an optical signal having a wavelength λ2. 26h '.

These two optical signals (λ1, λ2) are input to the second and fourth ports of the four-terminal circulator 25 ′ through the optical transmission lines 26g ′ and 26h ′, and are transmitted from the third and first ports. Output to the paths 26f 'and 26e'. The light is input to the input / output terminals of the optical demultiplexers 23 'and 24' through the optical transmission lines 26f 'and 26e', and is output from the input / output terminals to the optical transmission lines 26d 'and 26b'. Finally, the light is input to the optical receivers 22b 'and 22a' through the optical transmission lines 26d 'and 26b' and is extracted as an electric signal.

The transmission in the reverse direction, that is, the optical transmission / reception device 3
0 'to the optical transmitting / receiving device 30 is also transmitted in the same manner as described above.
This is performed by wavelength-multiplexing the signals of the different wavelengths λ1 ′ and λ2 ′. In this manner, bidirectional multiplex transmission of two wavelengths can be performed between the optical transmitting / receiving device 30 and the optical transmitting / receiving device 30 'through one optical transmission line 27.

[0095] Then, ₂ second optical multiplex transmission system 29 configured as above is, by performing the same operation as described above in parallel, through the optical transmission line 27 two, two-way,
In each direction, it is possible to transmit data at a transmission rate four times that in the case where multiplexing is not performed. That is, the same transmission as in the conventional example can be performed.

Further, the present optical bidirectional multiplex transmission system is characterized in that transmission can be performed in exactly the same manner as in the conventional example by using only two wavelengths of light, λ1 and λ2. As a result, only having two types of light sources,
Double speed transmission becomes possible. In addition, since the difference between the two wavelengths can be made large, it is possible to relax the tolerance of each center wavelength.

In the present embodiment, the following effect can be obtained in addition to the same effect as the first embodiment. That is, for example, in the optical multiplexing transmission / reception apparatus 30, when the place where the video signal is transmitted and received and the place where the data signal is transmitted and received are separated from each other, only one optical transmission line 26e or 2
It is only necessary to stretch 6f. Therefore, compared with the first embodiment in which two optical transmission lines need to be extended, the number of optical transmission components such as an optical fiber and an optical connector can be reduced, and as a result, the reliability of the entire optical transmission system can be improved. The cost can be reduced.

While the optical transmission systems according to the first and second embodiments of the present invention have been described above, in each optical transmitting / receiving apparatus, two or three optical demultiplexers (13, 1) are used.
4, 23, 24, 28), and the number of components is large. Therefore, third to fifth described below.
In the embodiment, an optical module which can integrally configure a plurality of optical demultiplexers used in an optical transmitting and receiving apparatus will be described. With such an optical module, a plurality of optical demultiplexers provided in each optical transmission / reception device can be integrally configured.
It is possible to reduce the number of components of the optical transmission system according to the embodiment.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
FIG. 4 is a plan view of the optical module according to the embodiment, and FIG. 5 is a front sectional view thereof (a sectional view taken along a dashed line in FIG. 4). 3 to 5, the present optical module is provided substantially at right angles to an optical waveguide substrate 35 and a main plane 35a of the optical waveguide substrate 35, and has a first wavelength (λ).
1) transmitting an optical signal and reflecting an optical signal having a second wavelength (λ2) different from the first wavelength, and an optical filter substrate 35 from one point on the optical filter 34. There are provided first to sixth optical waveguides 33a to 33f extending in the direction of the outer peripheral end faces (overcladding 31, undercladding 32) along the main plane 35a.

The first optical waveguide 33a includes the optical filter 3
4 and θ1. The second optical waveguide 33b has a first
Is on an extension of the optical waveguide 33a. Third optical waveguide 3
3c forms an angle of (180 ° −θ1) with the optical filter 34. The fourth optical waveguide 33d forms an angle of θ2 with the optical filter 34. The fifth optical waveguide 33e is on an extension of the fourth optical waveguide 33d. Sixth optical waveguide 33f
Makes an angle of (180 ° −θ2) with the optical filter 34.

The present optical module having the above-described configuration provides an optical signal (wavelength λ) input to the fifth optical waveguide 33e.
1) and the optical signal (wavelength λ2) input to the sixth optical waveguide 33f are multiplexed with each other, and the obtained optical multiplexed signal (wavelength λ1, λ2) is output from the fourth optical waveguide 33d. In addition, the optical multiplexed signal (wavelength λ1, λ2) input to the first optical waveguide 33a is demultiplexed, and one obtained optical signal (wavelength λ1) is transmitted from the second optical waveguide 33b to the other. The third optical waveguide 33c outputs an optical signal (wavelength λ2) from the third optical waveguide 33c.

Therefore, for example, the optical transceiver 20 shown in FIG.
The optical multiplexer 13 and the optical demultiplexer 14 included in (see the first embodiment) can be integrally configured by the present optical module. In this case, the optical transmission line 16a (the optical transmission unit 11a is connected to one end) shown in FIG. 1 corresponds to the fifth optical waveguide 33e of the optical module. Similarly, the optical transmission line 16b (the optical transmission unit 1
1b) corresponds to the sixth optical waveguide 33f, and the optical transmission line 16c (the optical receiving section 12a is connected to one end thereof) corresponds to the second optical waveguide 33b. The transmission line 16d (the optical transmission unit 12b is connected to one end thereof) corresponds to the third optical waveguide 33c, and the optical transmission line 1
6e (one end thereof is connected to the first port of the three-terminal circulator 15) corresponds to the fourth optical waveguide 33d, and the optical transmission line 16f (one end thereof is connected to the third port of the three-terminal circulator 15). Corresponds to the first optical waveguide 33a.

Further, the present optical module configured as described above outputs an optical signal (wavelength λ1) input to the fifth optical waveguide 33e from the fourth optical waveguide 33d, and An optical signal (wavelength λ2) input to the waveguide 33d is output from the sixth optical waveguide 33f, and an optical signal (wavelength λ1) input to the second optical waveguide 33b is output from the first optical waveguide 33a. And an optical signal (wavelength λ2) input to the first optical waveguide 33a is converted to a third optical waveguide 33c.
Has the effect of outputting from

Therefore, for example, the optical transmitting / receiving device 20 shown in FIG.
A pair of optical demultiplexers 2 included in (see the second embodiment)
3 and 24 can be integrally formed by the present optical module. In this case, the optical transmission line 26a shown in FIG. 2 (the optical transmission unit 21a is connected to one end).
Corresponds to the fifth optical waveguide 33e of the present optical module. Similarly, an optical transmission line 26e (having one end connected to the first port of the four-terminal circulator 25) corresponds to the fourth optical waveguide 33d, and an optical transmission line 26b (having an optical receiving unit 22a at one end thereof). Connected) corresponds to the sixth optical waveguide 33f, and the optical transmission line 26c (the optical transmission section 21b is connected to one end thereof) is connected to the first optical waveguide 33f.
a, the optical transmission path 26f (having one end connected to the third port of the four-terminal circulator 25)
This corresponds to the second optical waveguide 33b.

Hereinafter, the present optical module will be described more specifically. The under cladding 31 and the over cladding 32 are formed of a specific optical material such as a glass material or a resin material having substantially the same refractive index. The first to sixth optical waveguides 33a to 33f are also formed of a glass material having a specific refractive index, but have a higher refractive index than the under cladding 31 and the over cladding 32. Actually, the optical waveguides 33a to 33f are:
A so-called core portion, and optical waveguides 33a to 33f;
Since light is guided by the refractive index difference between the over cladding 31 and the under cladding 32, more precisely, these (31, 32 and 33a to 33f) cooperate to function as an "optical waveguide". However, for convenience of explanation, 33a to 33f are referred to as optical waveguides here.

The optical waveguides 33a to 33f are formed such that the ends serving as extraction portions are undercladding 31 or overcladding 32 so that they can be optically coupled to an optical fiber or an optical element.
And the other end is exposed to the optical filter 34.
It is formed to converge to one point (above). The optical waveguide substrate 35 is constituted by the under clad 31, the over clad 32, and the optical waveguides 33a to 33f.

The optical filter 34 has a characteristic of transmitting an optical signal of the wavelength λ1 and reflecting an optical signal of the wavelength λ2.
The optical waveguide substrate 35 is provided at a position perpendicular to the main surface 35a of the optical waveguide substrate 35 at a position where it comes into contact with the converged end of 33f. Here, the first optical waveguide 33a forms an angle of θ1 with the optical filter 34, and the second optical waveguide 33b
Extends substantially on the extension of the first optical waveguide 33a, and the third optical waveguide 33c is connected to the optical filter 34 and (1).
80 ° -θ1). Similarly, the fourth optical waveguide 33d forms an angle of θ2 with the optical filter 34, and the fifth optical waveguide 3e is connected to the first optical waveguide 33d.
Of the sixth optical waveguide 33f.
Is at an angle of (180 ° −θ2) with the optical filter 34.

The operation of the optical module configured as described above will be described. When an optical multiplexed signal, that is, an optical signal having the wavelength λ1 and an optical signal having the wavelength λ2, are transmitted to the first optical waveguide 33a, the optical signal having the wavelength λ1 passes through the optical filter 34, and is transmitted through the second optical waveguide 33a. The light is guided along 33b. On the other hand, the optical signal of the wavelength λ2 is reflected by the optical filter 34 and guided along the third optical waveguide 33c. Of course, the same applies to the case where light is guided in the opposite direction, and one optical demultiplexer is constituted by the first to third optical waveguides 33a to 33c. Similarly, the fourth to
Another optical demultiplexer is constituted by the sixth optical waveguides 33d to 33f. In this manner, two optical demultiplexers can be formed by one waveguide substrate, and the number of components can be reduced. Since the optical filter 34 and the like are particularly expensive, if two optical filters 34 having substantially the same area as that of one optical duplexer can be used to make two optical duplexers, the cost of components can be significantly reduced.

For example, in the optical transmitting / receiving device 20 provided in the optical transmission system (first embodiment) of FIG.
If the optical fibers 16e, 16a, 16b, 16f, 16c, and 16d are respectively coupled to the sixth optical waveguides 33a to 33f, the two optical demultiplexers 13 and 14 can be integrated.

Similarly, in the optical transmission / reception device 30 provided in the optical transmission system (second embodiment) of FIG.
If the optical fibers 26e, 26a, 26b, 26f, 26c, 26d are respectively coupled to the sixth optical waveguides 33a to 33f, the two optical demultiplexers 23, 24 can be integrated. In addition, it is also possible to integrate the three-way duplexer by a similar method.
4 and 28 may be constituted by one waveguide substrate.

Further, an optical element may be connected to the present optical module. FIG. 6 is a perspective view showing an example in which an optical element is coupled to the optical module of FIG. In FIG. 6, a first optical waveguide 33a has a first optical transmission line 37a for transmitting an optical multiplexed signal (wavelengths λ1, λ2) to be demultiplexed by an optical filter 34, and a second optical waveguide 33b. Is an optical filter 34
A first light receiving element 36a for receiving an optical signal of the wavelength λ1 obtained by demultiplexing is provided in the third optical waveguide 33c.
Second light receiving elements 36b for receiving an optical signal of wavelength λ2 obtained by splitting the optical filter 34 are optically coupled on the outer peripheral surface of the optical waveguide substrate 35, respectively.

Similarly, a first light emitting element 36c for transmitting an optical signal of wavelength λ1 to be multiplexed by the optical filter 34 is provided in the fifth optical waveguide 33e.
3f has a wavelength λ2 at which the optical filter 34 is about to combine.
A second light-emitting element 36d for transmitting the optical signal of the second type transmits the optical multiplexed signal (wavelengths λ1, λ2) obtained by multiplexing the optical filter 34 to the fourth optical waveguide 33d. The optical transmission paths 37b are optically coupled on the outer peripheral surface of the optical waveguide substrate 35, respectively.

As shown in FIG. 6, the second, third, fifth and sixth optical waveguides 33b, 33c, 33e and 33e
If optical transmitting / receiving elements 36a to 36d (light emitting elements such as laser diodes or light receiving elements such as pin photodiodes) are coupled to f, optical waveguides 33b, 33c, 3
It is not necessary to provide an optical fiber between 3e and 33f and the optical transmitting / receiving elements 36a to 36d, and it is possible to further reduce the number of components of the optical transmission system.

As described above, according to the present embodiment, the configuration of the optical transmission system can be simplified and the price can be reduced.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention.
8 is a front cross-sectional view (cross-sectional view taken along dashed-dotted line 45b in FIG. 7) of the optical module according to the embodiment. FIG. 8A shows the optical path of the optical signal having the wavelength λ2, and FIG. 8B shows the optical path of the optical signal having the wavelength λ1 by broken lines.

In FIG. 7, the present optical module includes first to first optical modules.
Sixth optical fibers 42a to 42f, a lens 41, an optical filter 43 that transmits an optical signal of wavelength λ1 and reflects an optical signal of wavelength λ2, and a mirror 44 are provided.
The optical filter 43 is located at the first focal position of the lens 41,
It is arranged at right angles to the optical axis of the lens 41 (indicated by the dashed line in FIG. 8).

The first to sixth optical fibers 42a to 42f
The center of each end face is arranged in a line and at equal intervals in this order, and the midpoint between the center of the end face of the second optical fiber and the center of the end face of the third optical fiber is the second point of the lens 41. It is provided so as to come to the focal position.

The mirror 44 is located near the optical filter 43 and on the side opposite to the lens 41.
Are provided at a predetermined angle with respect to This inclination angle is such that the optical signal of wavelength λ2 emitted from the end face of the first optical fiber 42a is reflected and made incident on the end face of the sixth optical fiber 42f.

In this case, in the present optical module, the optical signal of the wavelength λ2 emitted from the first optical fiber 42a is reflected by the optical filter 43 as shown by the dotted line in FIG. 4 enters the optical fiber 42d. Similarly, the optical signal of the wavelength λ2 emitted from the second optical fiber 42b is reflected by the optical filter 43 and enters the third optical fiber 42c.

On the other hand, the optical signal of wavelength λ1 emitted from the first optical fiber 42a passes through the optical filter 43, is reflected by the mirror 44, and is reflected again by the light as shown by the dotted line in FIG. 8B. The sixth optical fiber 42 passing through the filter
f. Similarly, the optical signal of wavelength λ1 emitted from the second optical fiber 42b passes through the optical filter 43, is reflected by the mirror 44, passes through the optical filter again, and enters the fifth optical fiber 42e. .

The present optical module having the above-described configuration includes an optical signal (wavelength λ1) input to the fifth optical fiber 42e and an optical signal (wavelength λ2) input to the third optical fiber 42c. Are multiplexed with each other, and the obtained optical multiplexed signal (wavelengths λ1, λ2) is output from the second optical fiber 42b, and the optical multiplexed signal (wavelengths λ1, λ2) input to the first optical fiber 42a is output. ), The obtained one optical signal (wavelength λ1) is obtained from the sixth optical fiber 42f, and the other optical signal (wavelength λ2) is obtained from the fourth optical fiber 42d.
Each has an output function.

Therefore, for example, the optical transceiver 20 shown in FIG.
The optical multiplexer 13 and the optical demultiplexer 14 included in (see the first embodiment) can be integrally configured by the present optical module. In this case, the optical transmission line 16a (the optical transmission section 11a is connected to one end) shown in FIG. 1 corresponds to the fifth optical fiber 42e of the present optical module. Similarly, the optical transmission line 16b (the optical transmission unit 11b is connected to one end of the optical transmission line 16b) is connected to the third optical fiber 42c.
Corresponding to the optical transmission line 16c (the optical receiving section 12a
Is connected) to the sixth optical fiber 42f, and the optical transmission line 16d (the optical transmission section 12b is connected to one end thereof) corresponds to the fourth optical fiber 42d. The path 16e (having one end connected to the first port of the three-terminal circulator 15) corresponds to the second optical fiber 42b, and the optical transmission path 16f (having one end connected to the third port of the three-terminal circulator 15). Has been)
Corresponds to the first optical fiber 42a.

Further, the present optical module configured as described above outputs an optical signal (wavelength λ1) input to the fifth optical fiber 42e from the second optical fiber 42b, and outputs the second optical signal. An optical signal (wavelength λ2) input to the fiber 42b is output from the third optical fiber 42c, and an optical signal (wavelength λ1) input to the sixth optical fiber 42f.
Is output from the first optical fiber 42a, and the optical signal (wavelength λ2) input to the first optical fiber 42a is
Of the optical fiber 42d.

Therefore, for example, the optical transmitting / receiving device 20 shown in FIG.
A pair of optical demultiplexers 2 included in (see the second embodiment)
3 and 24 can be integrally formed by the present optical module. In this case, the optical transmission line 26a shown in FIG. 2 (the optical transmission unit 21a is connected to one end).
Corresponds to the fifth optical fiber 42e of the present optical module. Similarly, the optical transmission line 26e (the first port of the four-terminal circulator 25 is connected to one end thereof) corresponds to the second optical fiber 42b, and the optical transmission line 26b (the optical receiving unit 22a is provided at one end thereof). Connected) corresponds to the third optical fiber 42c, and the optical transmission line 26c (the optical transmission section 21b is connected to one end thereof) corresponds to the fourth optical fiber 42d. 26f (one end of which is connected to the third port of the four-terminal circulator 25 is connected) corresponds to the first optical fiber 42a, and the optical transmission line 26d (the optical receiving unit 22a is connected to one end thereof). Corresponds to the sixth optical fiber 42f.

Hereinafter, the present optical module will be described more specifically. Here, the lens 41 is of a refractive index distribution type, and the length of the lens is determined so that the lens end surface 41a coincides with the focal plane. The first to sixth optical fibers 42a to 42f are arranged in parallel with each other such that their end faces are arranged at equal intervals on the focal plane of the lens 41. Since the lens 41 has a length such that the lens end face 41a coincides with the focal plane, the end faces of the first to sixth optical fibers 42a to 42f are shaped to abut the lens end face 41a. The midpoint between the center of the end face of the second optical fiber 42b and the center of the end face of the third optical fiber 42d is the optical axis of the lens 41 (that is, the lens end face 41).
(center of a).

The optical filter 43 is a filter that transmits light having the wavelength λ1 and reflects light having the wavelength λ2, and is provided on one end surface 41b of the lens at right angles to the optical axis.
Here, the case where the lens 41 whose lens end surface 41b is perpendicular to the optical axis is used is shown.
Reference numeral 3 is attached to the lens end face 41b in close contact. The mirror 44 is installed on the lens end surface 41b side at a predetermined angle described later.

Next, the operation of the optical demultiplexer configured as described above will be described. First, the case where light of wavelength λ2 has propagated through the optical fiber will be described. The light of wavelength λ2 that has propagated through the first optical fiber 42a enters the lens 41 from the lens end face 41a. Lens end face 4
Since 1a coincides with the focal plane, this light becomes parallel light when it reaches the lens end face 41b. Since the optical filter 43 is attached to the lens end surface 41b, the light having the wavelength λ2 is reflected by the optical filter 43,
The lens advances in the lens 41 in the reverse direction, and forms an image at one point on the lens end surface 41a.

This image forming point is a point symmetrical position with respect to the center of the first optical fiber 41a with respect to the center of the lens end face 41a as a symmetric point. That is, the imaging point coincides with the center of the fourth optical fiber 42d, and the light propagates through the fourth optical fiber 42d. Similarly, the light that has propagated through the second optical fiber 42b and exited from the end face is transmitted to the lens end face 41 by the lens 41 and the optical filter 43.
With the center of a being a point of symmetry, an image is formed at the center of the third optical fiber 41c located at a point symmetrical position with respect to the center of the second optical fiber 41b, and propagates through the third optical fiber 41c.

Next, the first optical fiber 42a is set to the wavelength λ1.
This is the case where this light is propagated, but this light becomes parallel light when it enters the lens 41 and reaches the lens end face 41b. However, since the light is of wavelength λ1,
The light passes through the optical filter 43, is reflected by the mirror 44, enters the lens 41 again, and forms an image on the lens end surface 41a. This imaging position is determined by the installation angle of the mirror 44.

Here, the set angle of the mirror 44 is determined so that the image forming position coincides with the center of the sixth optical fiber 42f. Accordingly, light radiated from a point on the lens end surface 41a and incident on the lens 41 is a point having a center point between the center of the third optical fiber 42c and the center of the fourth optical fiber 42d as a symmetric point. An image is formed at a symmetric position. Therefore, the light having the wavelength λ1 that has propagated through the second optical fiber 42b is point-symmetrically positioned at the center of the fourth optical fiber 42d with respect to the center of the fourth optical fiber 42d by the lens 41 and the mirror 44. No. 5 forms an image at the center of the optical fiber 42e and propagates through the optical fiber 42e.

As described above, the first optical fiber 42
The light having the wavelength λ1 and the light having the wavelength λ2 (that is, the optical multiplexed signal) that have propagated through the second optical fiber 42f
And the fourth optical fiber 42d.
That is, the present optical module functions as one optical demultiplexer. Of course, when light propagates in the opposite direction,
Functions as an optical multiplexer. Also, the second optical fiber 42
The light of wavelength λ1 and the light of wavelength λ2 that have propagated b
The fifth optical fiber 42e and the third optical fiber 4
2c. That is, the optical module functions as another duplexer. As described above, the present optical module is one in which two splitters or multiplexers are integrated.

As described above, according to the present embodiment, two optical demultiplexers can be integrated with a small number of components, and a low-cost optical transmission system can be realized. .

In the fourth embodiment described above, the lens 41 is of a refractive index distribution type, and the lens end face 41a has the same focal plane.
Positioning of the end faces 2a to 42f in the optical axis direction and positioning of the optical filter 43 are facilitated. However,
The effect that the two splitters can be integrated is, of course, not limited to a gradient index lens. For example, even when a thin convex lens is used, if the end faces of the optical fibers 42a to 42f are similarly arranged on the focal plane of the lens, the two duplexers can be integrated.

(Fifth Embodiment) FIG. 9 shows a fifth embodiment of the present invention.
It is a perspective view of the optical module which concerns on 2nd Embodiment. In FIG. 9, the present optical module includes first to seventh optical fibers 5.
2a to 52g, a lens 51, and an optical filter 5 that transmits an optical signal of wavelength λ1 and reflects an optical signal of wavelength λ2.
3 and a mirror 54. Optical filter 53
Is disposed at one focal position of the lens 51 at right angles to the optical axis of the lens 51.

First to seventh optical fibers 52a to 52g
Is that the second to seventh optical fibers 52b to 52g are closely arranged in this order around the first optical fiber 52a, and the center of the end face of the first optical fiber 52a and the third optical fiber 52b to 52g. The center point between the center of the end face of the optical fiber 52c and the lens 5 is
1 is provided so as to come to the other focal position. Therefore,
The centers of the respective end faces of the second to seventh optical fibers 52b to 52g are arranged at equal intervals in this order (every 60 degrees) on a concentric circle centered on the center of the first optical fiber 52a. 3) the third, first and sixth optical fibers 5
The center of each end face of 2c, 52a and 52f is connected to one main shaft 5
The centers of the end faces of the fourth and second optical fibers 52d and 52b are arranged in a line along the other main axis 55b.

Here, the seventh optical fiber 52g is connected to the first optical fiber 52g.
Of the second to sixth optical fibers 52b to 52
This is a dummy optical fiber provided for stably disposing 52f, and does not propagate any optical signal. Therefore, if the positional relationship between the optical fibers can be maintained as described above by some other method, the seventh optical fiber 52
g may be removed from the optical module.

The mirror 54 is located near the optical filter 53 and on the opposite side of the lens 51 from the optical filter 5.
3 is provided at a predetermined angle with respect to 3. This inclination angle is such that the optical signal of wavelength λ1 emitted from the end face of the third optical fiber 52c is reflected and made incident on the end face of the sixth optical fiber 52f.

In this case, in the present optical module, the optical signal having the wavelength λ2 emitted from the first optical fiber 52a is reflected by the optical filter 53 and enters the fifth optical fiber 52d. Similarly, the optical signal of the wavelength λ2 emitted from the second optical fiber 52b is reflected by the optical filter 53 and enters the third optical fiber 52c.

On the other hand, the optical signal of wavelength λ1 emitted from the first optical fiber 52a passes through the optical filter 53, is reflected by the mirror 54, passes through the optical filter again, and passes through the sixth optical filter.
To the optical fiber 52f. Similarly, the optical signal of wavelength λ1 emitted from the second optical fiber 52b passes through the optical filter 53, is reflected by the mirror 54, passes through the optical filter again, and enters the fifth optical fiber 52e. .

The present optical module having the above-described configuration is configured such that an optical signal (wavelength λ1) input to the fifth optical fiber 52e and an optical signal (wavelength λ2) input to the third optical fiber 52c are used. Are multiplexed with each other, and the obtained optical multiplexed signal (wavelength λ1, λ2) is output from the second optical fiber 52b, and the optical multiplexed signal (wavelength λ1, λ2) input to the first optical fiber 52a is output. ), The obtained one optical signal (wavelength λ1) is obtained from the sixth optical fiber 52f, and the other optical signal (wavelength λ2) is obtained from the fourth optical fiber 52d.
Each has an output function.

Therefore, for example, the optical transmitting / receiving device 20 shown in FIG.
The optical multiplexer 13 and the optical demultiplexer 14 included in (see the first embodiment) can be integrally configured by the present optical module. In this case, the optical transmission line 16a (the optical transmission section 11a is connected to one end thereof) shown in FIG. 1 corresponds to the fifth optical fiber 52e of the present optical module. Similarly, the optical transmission line 16b (the optical transmission section 11b is connected to one end thereof) is connected to the third optical fiber 52c.
Corresponding to the optical transmission line 16c (the optical receiving section 12a
Is connected) to the sixth optical fiber 52f, and the optical transmission line 16d (the optical transmission unit 12b is connected to one end thereof) corresponds to the fourth optical fiber 52d. The path 16e (having one end connected to the first port of the three-terminal circulator 15) corresponds to the second optical fiber 52b, and the optical transmission path 16f (having one end connected to the third port of the three-terminal circulator 15). Has been)
Corresponds to the first optical fiber 52a.

Further, in the present optical module configured as described above, the optical signal (wavelength λ1) input to the fifth optical fiber 52e is output from the second optical fiber 52b, and the second optical An optical signal (wavelength λ2) input to the fiber 52b is output from the third optical fiber 52c, and an optical signal (wavelength λ1) input to the sixth optical fiber 52f.
Is output from the first optical fiber 52a, and the optical signal (wavelength λ2) input to the first optical fiber 52a is output to the fourth optical fiber 52a.
Output from the optical fiber 52d.

Accordingly, for example, the optical transceiver 20 shown in FIG.
A pair of optical demultiplexers 2 included in (see the second embodiment)
3 and 24 can be integrally formed by the present optical module. In this case, the optical transmission line 26a shown in FIG. 2 (the optical transmission unit 21a is connected to one end).
Corresponds to the fifth optical fiber 52e of the present optical module. Similarly, the optical transmission line 26e (the first port of the four-terminal circulator 25 is connected to one end thereof) corresponds to the second optical fiber 52b, and the optical transmission line 26b (the optical receiving unit 22a is provided at one end thereof). Connected) corresponds to the third optical fiber 52c, and the optical transmission line 26c (the optical transmission section 21b is connected to one end thereof) corresponds to the fourth optical fiber 52d. 26f (one end of which is connected to the third port of the four-terminal circulator 25) corresponds to the first optical fiber 52a, and the optical transmission line 26d (the one end of which is connected to the optical receiver 22a). Corresponds to the sixth optical fiber 52f.

Hereinafter, the optical module will be described more specifically. The lens 51 is of a refractive index distribution type similarly to the fourth embodiment, and the length of the lens end surface 41a coincides with the focal plane. The first to seventh optical fibers 52a to 52g have their end faces set to the lens end face 41.
They are arranged in parallel so as to abut each other. These seven fibers are optical fibers having the same outer diameter. By arranging the other six optical fibers 52b to 52g in close contact with the first optical fiber 52a, the first optical fiber The fibers 52a are arranged at intervals of 60 ° on the same circumference with the center as the center. Also,
The center of the center of the end face of the first optical fiber 52a and the center of the end face of the third optical fiber 52c are arranged so as to coincide with the optical axis of the lens 51 (that is, the center of the lens end face 51a).

The optical filter 53 is a filter that transmits light of wavelength λ1 and reflects light of wavelength λ2.
1 is provided on one end surface 51b side at right angles to the optical axis. Here, a case is shown in which the lens 51 whose lens end face 51b is perpendicular to the optical axis is used, and the optical filter 53 is adhered to the lens end face 51b in close contact.

With the above configuration, similarly to the fourth embodiment, the light of wavelength λ2 emitted from the optical fiber having the end face disposed on the lens end face 51a is transmitted to the lens end face 51a by the lens 51 and the optical filter 53. An image is formed at a point symmetric position with the center as a symmetric point. That is, the light of wavelength λ2 that has propagated through the second optical fiber 52b is
3 and propagates through the fourth optical fiber 54d. The light having the wavelength λ2 that has propagated through the third optical fiber 52c is reflected by the optical filter 53, and
Of the optical fiber 54a.

The mirror 54 is installed on the lens end face 51b side so as to be inclined with respect to the lens end face 51b. At this time, the angle is adjusted so that the light emitted from the third optical fiber 52c forms an image at the end face position of the sixth optical fiber 52f. As a result, the light of wavelength λ1 emitted from the optical fiber having the end face disposed on the lens end face 51a is transmitted to the first optical fiber 52a by the lens 51 and the mirror 54.
Is formed at a point symmetrical position with the center of the end face of as a symmetrical point. That is, the light of wavelength λ1 that has propagated through the second optical fiber 52b is reflected by the mirror 54,
The light of wavelength λ1 that has propagated through the third optical fiber 52c is reflected by the mirror 54 and propagates through the sixth optical fiber 54f. .

As described above, the third optical fiber 52
The light having the wavelength λ1 and the light having the wavelength λ2 (that is, the optical multiplexed signal) that have propagated through the third optical fiber 52f
And the first optical fiber 52a.
That is, the present optical module functions as one optical demultiplexer. Of course, when the light propagates in the opposite direction, it functions as an optical multiplexer.

The light having the wavelength λ1 and the light having the wavelength λ2 (that is, the optical multiplexed signal) transmitted through the second optical fiber 52b are demultiplexed to the fifth optical fiber 52e and the fourth optical fiber 52d, respectively. Will be done. That is, the optical module functions as another duplexer.
As described above, the present optical module is one in which two splitters or multiplexers are integrated.

As described above, according to the present embodiment, two optical demultiplexers can be integrated with a small number of components, and a low-cost optical transmission system can be realized. . What is different from the fourth embodiment is that
Seven optical fibers 52a to 52g are arranged so that the other six optical fibers 52b to 52g are in close contact with each other around the first optical fiber 52a. The components can be easily aligned based on the outer diameter of the optical fiber without requiring any components.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical bidirectional multiplex transmission system according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an optical bidirectional multiplex transmission system according to a second embodiment of the present invention.

FIG. 3 is a perspective view of an optical module according to a third embodiment of the present invention.

FIG. 4 is a plan view of an optical module according to a third embodiment of the present invention.

FIG. 5 is a front sectional view (a sectional view taken along a dashed line in FIG. 4) of an optical module according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing an example in which an optical element is coupled to the optical module of FIG.

FIG. 7 is a perspective view of an optical module according to a fourth embodiment of the present invention.

FIG. 8 is a front cross-sectional view (a cross-sectional view taken along a dashed-dotted line in FIG. 7).

FIG. 9 is a perspective view of an optical module according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration example of a conventional optical bidirectional multiplex transmission system.

[Explanation of symbols]

11a, 11b Optical transmitters 12a, 12b Optical receivers 13 Optical multiplexers 14 Optical demultiplexers 15 Three-terminal circulators 16a to 16f, 17 Optical transmission paths 18 ₁ to 18 _n Optical bidirectional multiplexing systems 20 Optical transceivers 21a, 21b light transmitting portions 22a, 22b light receiving portions 23 and 24 optical demultiplexer 28 bidirectional optical multiplexing demultiplexer 25 four-terminal circulator 26 a to 26 h, 27 optical transmission line 29 ₁ ~ 29 _n light bidirectional multiplex system 30 optical transceiver 33a-33f, 42a-42f, 45a-42g Optical waveguides 34, 43, 53 Optical filters 41, 51 Lenses 44, 54 Mirrors

Claims (20)

[Claims] 1. An optical bidirectional multiplex transmission system for multiplexing two optical signals having wavelengths different from each other and transmitting the multiplexed signals bidirectionally, comprising a pair of optical transceivers, wherein each optical transceiver is mutually First and second optical transmitters for transmitting two optical signals having different wavelengths, two optical signals having two input terminals and one output terminal, and having two different input wavelengths An optical multiplexer that has one input terminal and two output terminals, splits an input optical multiplexed signal into two optical signals having different wavelengths, and outputs An optical demultiplexer, first and second optical receivers for receiving two optical signals having mutually different wavelengths, and an optical signal input to the first port is output from the second port, and Light input to two ports A three-terminal circulator for outputting a signal from a third port, the second ports of the three-terminal circulators provided in each of the optical transceivers are connected to each other via an optical transmission path, and each of the optical transceivers is The first and second
Is connected to two input terminals of the optical multiplexer, an output terminal of the optical multiplexer is connected to a first port of the three-terminal circulator, and a third port of the three-terminal circulator is connected to the optical An optical bidirectional multiplex transmission system, wherein the optical duplexer is connected to an input end of a duplexer, and two output ends of the optical splitter are connected to the first and second optical receivers. 2. The optical bidirectional multiplexing apparatus according to claim 1, wherein the wavelengths of the two optical signals multiplex-transmitted in the forward direction are the same as the wavelengths of the two optical signals multiplex-transmitted in the reverse direction. Transmission system. 3. A plurality of pairs of the optical transmission / reception devices, wherein the plurality of pairs of the optical transmission / reception devices execute operations of multiplexing two optical signals and transmitting the signals in two directions in parallel. 3. The optical bidirectional multiplex transmission system according to claim 2, wherein: 4. An optical bidirectional multiplex transmission system for multiplexing two optical signals having mutually different wavelengths and transmitting the multiplexed signals bidirectionally, comprising a pair of optical transceivers, wherein each optical transceiver is mutually A first and a second optical transmitter for transmitting two optical signals having different wavelengths, having two input / output terminals and one multiplexed input / output terminal;
Two input optical signals having different wavelengths are multiplexed with each other and output, and the input optical multiplexed signal is
An optical bidirectional demultiplexer for demultiplexing and outputting two optical signals having different wavelengths; a first and a second optical receiver for receiving two optical signals having different wavelengths; an input terminal A pair of optical demultiplexers that output the optical signal input to the input / output terminal from the input / output terminal, and output the optical signal input to the input / output terminal from the output terminal; An optical signal output from the two ports and input to the second port is output from the third port, an optical signal input to the third port is output from the fourth port, and
A four-terminal circulator for outputting an optical signal input to a port from a first port, wherein multiplexed input / output terminals of optical bidirectional multiplex / demultiplexers provided in each of the optical transmission / reception devices are mutually connected via an optical transmission path; In each of the optical transmitting and receiving devices, the input terminal of one of the optical demultiplexers is connected to the first optical transmitting unit, and the input / output terminal of the optical demultiplexer is connected to the input terminal of the four-terminal circulator. 1 port, and the output end of the optical demultiplexer is connected to the first port.
The input end of the other optical demultiplexer is connected to the second optical transmission unit, and the input / output end of the optical demultiplexer is connected to the third port of the four-terminal circulator. Connected, and the output end of the optical demultiplexer is connected to the second optical receiver, and the second and fourth ports of the four-terminal circulator are connected to two input / output terminals of the optical bidirectional multiplex demultiplexer. An optical two-way multiplex transmission system, characterized by being connected to: 5. The optical bidirectional multiplexing apparatus according to claim 4, wherein the wavelengths of the two optical signals multiplex-transmitted in the forward direction are the same as the wavelengths of the two optical signals multiplex-transmitted in the reverse direction. Transmission system. 6. A plurality of sets of said pair of optical transmitting and receiving devices, wherein said plurality of pairs of optical transmitting and receiving devices execute operations of multiplexing two optical signals and transmitting the signals in two directions in parallel. The optical bidirectional multiplex transmission system according to claim 5, wherein 7. An optical signal having a first wavelength and said first optical signal having a first wavelength.
An optical signal having a second wavelength different from the above wavelength is multiplexed with each other, and / or an input optical multiplexed signal is an optical signal having the first wavelength and the second wavelength is a leading example. An optical module for splitting an optical signal into an optical signal, comprising: an optical waveguide substrate; and an optical module provided substantially perpendicular to a main plane of the optical waveguide substrate, transmitting the optical signal having the first wavelength, and An optical filter that reflects an optical signal having a second wavelength; and first to sixth optical waveguides extending from one point on the optical filter along a main plane of the optical waveguide substrate toward an outer peripheral end face. The first optical waveguide forms an angle of θ1 with the optical filter; the second optical waveguide is on an extension of the first optical waveguide; and the third optical waveguide is formed of the optical filter. And (180 °
-Θ1), the fourth optical waveguide makes an angle of θ2 with the optical filter, the fifth optical waveguide is on an extension of the fourth optical waveguide, and the sixth optical waveguide The optical waveguide is connected to the optical filter by (180 °).
An optical module having an angle of -θ2). 8. The optical multiplexer and the optical demultiplexer are integrally formed by the optical module according to claim 3.
The optical bidirectional multiplex transmission system according to claim 2. 9. The optical bidirectional multiplex transmission system according to claim 5, wherein the pair of optical demultiplexers is integrally formed by the optical module according to claim 3. 10. The first optical waveguide includes a first optical transmission line for transmitting an optical multiplex signal to be demultiplexed by the optical filter, and the second optical waveguide includes an optical filter. A first for receiving an optical signal having a first wavelength obtained by demultiplexing
A light receiving element for receiving an optical signal having a second wavelength obtained by splitting the optical filter in the third optical waveguide.
A light emitting element for transmitting an optical signal having a first wavelength to which the optical filter is to be multiplexed, the light receiving element of the sixth optical waveguide; A second optical signal for transmitting an optical signal having a second wavelength to be multiplexed by the optical filter.
A light-emitting element, wherein a second optical transmission path for transmitting an optical multiplexed signal obtained by multiplexing the optical filter is provided on the fourth optical waveguide, on the outer peripheral surface of the optical waveguide substrate. The optical module according to claim 7, wherein the optical module is optically coupled. 11. The first optical transmitter, the second optical transmitter, the optical multiplexer, the optical demultiplexer, the first optical receiver, and the second optical receiver, 11. The optical module according to claim 10, wherein the optical module is integrally formed.
2. The optical bidirectional multiplex transmission system according to 1. 12. The apparatus according to claim 10, wherein the first optical transmitter, the second optical transmitter, the pair of optical demultiplexers, the first optical receiver, and the second optical receiver are configured as described in claim 10. The optical bidirectional multiplex transmission system according to claim 5, wherein the optical module is integrally configured by the optical module. 13. An optical signal having a first wavelength and an optical signal having a second wavelength different from the first wavelength are multiplexed with each other and / or an input optical multiplexed signal is converted into an optical multiplexed signal. An optical module for demultiplexing an optical signal having a first wavelength and an optical signal having a second wavelength, wherein the first to sixth optical fibers, a lens, and the first wavelength Transmitting an optical signal having
An optical filter that reflects an optical signal having a wavelength of: and a mirror, wherein the optical filter is located at one focal position of the lens,
The first to sixth optical fibers are arranged at right angles to the optical axis of the lens, and the end face centers of the first to sixth optical fibers are arranged in a line and at equal intervals in this order. The center between the center of the end face of the second optical fiber and the center of the end face of the third optical fiber is provided at the other focal position of the lens, and the mirror is located near the optical filter. And an optical signal having a first wavelength emitted from an end face of the first optical fiber, the optical signal being provided at a predetermined angle with respect to the optical filter on a side opposite to the lens. The optical module is characterized in that the angle is such that the light is reflected to enter the end face of the sixth optical fiber. 14. The optical multiplexer and the optical demultiplexer,
The optical bidirectional multiplex transmission system according to claim 2 or 3, wherein the optical module is configured integrally with the optical module according to claim 13. 15. The optical module according to claim 13, wherein the pair of optical demultiplexers are integrally formed.
Or the optical bidirectional multiplex transmission system according to 6. 16. An optical signal having a first wavelength and an optical signal having a second wavelength different from the first wavelength are multiplexed with each other and / or an input optical multiplexed signal is converted into an optical multiplexed signal. An optical module for demultiplexing an optical signal having a first wavelength and an optical signal having a second wavelength, wherein the first to seventh optical fibers, a lens, and the first wavelength Transmitting an optical signal having
An optical filter that reflects an optical signal having a wavelength of: and a mirror, wherein the optical filter is located at one focal position of the lens,
The first to seventh optical fibers are arranged at right angles to the optical axis of the lens, and the second to seventh optical fibers are in close contact with each other around the first optical fiber in this order. And the center of the center of the end surface of the first optical fiber and the center of the center of the end surface of the third optical fiber are provided at the other focal position of the lens. An optical filter is provided in the vicinity of the optical filter and opposite to the lens at a predetermined angle with respect to the optical filter, and the tilt angle is the first light emitted from the end face of the third optical fiber. An optical signal having an angle such that an optical signal having a wavelength of? Is reflected and made incident on the end face of the sixth optical fiber. 17. The optical multiplexer and the optical demultiplexer,
The optical bidirectional multiplex transmission system according to claim 2 or 3, wherein the optical module is configured integrally with the optical module according to claim 16. 18. The optical module according to claim 16, wherein the pair of optical demultiplexers is integrally formed by the optical module according to claim 16.
Or the optical bidirectional multiplex transmission system according to 6. 19. An optical bidirectional multiplex transmission / reception device for multiplexing two optical signals having different wavelengths and transmitting the signal in two directions, the two-way multiplex transmission / reception device for transmitting two optical signals having different wavelengths. A first and a second optical transmitter, an optical multiplexer having two input terminals and one output terminal, and multiplexing and outputting two input optical signals having different wavelengths from each other; An optical demultiplexer that has two input terminals and two output terminals and that splits an input optical multiplexed signal into two optical signals having different wavelengths and outputs the two signals; two optical demultiplexers having different wavelengths A first and a second optical receiver for receiving an optical signal, and an optical signal input to the first port is output from the second port, and an optical signal input to the second port is output from the third port. Three-terminal circular output A second port of the three-terminal circulator is connected to an optical transmission line, the first and second optical transmitters are connected to two input terminals of the optical multiplexer, and an output of the optical multiplexer is provided. An end is connected to a first port of the three-terminal circulator, a third port of the three-terminal circulator is connected to an input end of the optical demultiplexer, and two output ends of the optical demultiplexer are the first and the second. An optical bidirectional multiplex transmission / reception device connected to a second optical reception unit. 20. An optical bidirectional multiplex transmission / reception apparatus for multiplexing two optical signals having different wavelengths and transmitting the signals in two directions, comprising transmitting and receiving two optical signals having different wavelengths. A first and a second optical transmitter, having two input / output terminals and one multiplexed input / output terminal;
Two input optical signals having different wavelengths are multiplexed with each other and output, and the input optical multiplexed signal is
An optical bidirectional demultiplexer for demultiplexing and outputting two optical signals having different wavelengths; a first and a second optical receiver for receiving two optical signals having different wavelengths; an input terminal A pair of optical demultiplexers that output the optical signal input to the input / output terminal from the input / output terminal, and output the optical signal input to the input / output terminal from the output terminal; An optical signal output from the two ports and input to the second port is output from the third port, an optical signal input to the third port is output from the fourth port, and
A four-terminal circulator for outputting an optical signal input to a port from a first port; a multiplexed input / output terminal of the optical bidirectional multiplex demultiplexer is connected to an optical transmission line; An input terminal is connected to the first optical transmitter, an input / output terminal of the optical demultiplexer is connected to a first port of the four-terminal circulator, and an output terminal of the optical demultiplexer is connected to the first terminal. The input end of the other optical demultiplexer is connected to the second optical transmission unit, and the input / output end of the optical demultiplexer is connected to the third port of the four-terminal circulator. Connected, and the output end of the optical demultiplexer is connected to the second optical receiver, and the second and fourth ports of the four-terminal circulator are connected to two input / output terminals of the optical bidirectional multiplex demultiplexer. An optical two-way multiplex transmission system, characterized by being connected to: