JPS619041A - Photodetecting or light emitting device for optical communication - Google Patents

Abstract

PURPOSE:To eliminate an individual multiplexing/demultiplexing device by constituting separately a light emitting element and a photodetector and providing a wavelength selecting function to each so as to constituted a light emitting device or a photodetector. CONSTITUTION:An optical signal incident in an optical input terminal 3 is condensed by a photodetector lens 5, reflected in an interference membrane filter 9 and outputted externally from an optical output terminal 4. On the other hand, in impressing an electric signal including a signal to be transmitted to an electric signal input terminal 11 of a light emitting element 10, a specific wavelength light is transmitted from the light emitting element. Since this is constituted to transmit an interference filter, the light is mixed with an emitted light and outputted externally from an emitting terminal. A light of a wavelength specific to the interference filter in the light incident from the optical input terminal 3 is transmitted in an input device based on the same principles and reaches a photodetector 12, and an eletric signal is outputted to the output terminal 13, the light other than the said wavelength is reflected by the said interference filter and outputted externally from the output terminal 4.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a light receiving or emitting device used in wavelength multiplexed optical communication, etc.
In particular, it relates to a light receiving or light emitting device having a multiplexing/demultiplexing function.

(Prior art) In conventional wavelength division multiplexing transmission systems for optical communication, multiple channels of electrical signals drive light emitting elements such as light emitting diodes or laser diodes, each with a different wavelength, and their optical outputs are combined by a multiplexer. A method is to combine the signals and propagate them on the same optical transmission path such as an optical fiber. On the receiving side, on the other hand, the received optical signal is separated by a demultiplexer and converted into an electrical signal by a light receiving element such as a PIN diode or an avalanche diode corresponding to each channel. In addition, for the purpose of effective use of optical transmission lines, two-way communication is also carried out using the same transmission line, such as the transmission wavelength fittings of opposing optical communication devices. A multiplexer/demultiplexer is used to separate the sending and receiving optical signals.

Conventionally, in the input/output section of a wavelength multiplexing transmission device, a light emitting element for each wavelength, a light receiving element, and a multiplexer/demultiplexer are configured as individual devices, and these are connected by a light guide such as an optical fiber for input/output. It was common to use it as a device.

Furthermore, the possible transmission distance of a wavelength division multiplexing transmission system depends on the amount of insertion loss and leakage of the multiplexer/demultiplexer, and the number of channels that can be transmitted on the same line depends on the number of terminals that can be connected to the input/output j mK of the multiplexer/demultiplexer. Naturally limited.

In particular, when fiber is used as a transmission line, since the fiber core is small in diameter, the assembly of the input/output terminals of the multiplexer/demultiplexer and the spectroscopic system inside the multiplexer/demultiplexer, which is usually formed by an optical fiber connector or a fiber cord with a plug, is particularly important. High precision is also required for parts processing, and this tendency becomes more pronounced as the number of multiplexed channels increases. Furthermore, this multiplexer/demultiplexer needs to have specific characteristics depending on the wavelength used and the number of multiplexed channels, and if a multiplexer/demultiplexer with the required characteristics cannot be obtained, the number of multiplexed channels and its system are required. configuration will be subject to significant restrictions.

Furthermore, connecting one multiplexer/demultiplexer to each element using a fiber cord increases the number of fiber wires within the device, which increases fiber connector terminal processing, increases insertion loss, and affects the possible transmission distance. There was the problem of giving

(Problems to be Solved by the Invention) As mentioned above, in the conventional wavelength division multiplexing transmission method in optical communication, multiple wavelength signals are sent on the same optical transmission path. The input/output device includes a light emitter, a light receiver, and a multiplexer/demultiplexer having input/output ends for the same number of channels and the same number of channels, connected by a light guide.

The characteristics of these multiplexers and demultiplexers differ depending on the number of channels in the communication system and the wavelength used, and not only do they become extremely expensive as the number of channels increases, but also due to the wavelength characteristics of the nine multiplexers and demultiplexers, The usable wavelength range, that is, the light source used is limited.

This also includes the problem of having to replace the entire device, resulting in a large burden of work and equipment costs.

(Means for Solving the Problems) The present invention has been made in order to solve these problems in conventional optical multiplex communication.

The light receiving or emitting device has the following configuration.

By configuring the conventional light emitting element and light receiving element separately and giving each one a wavelength selection function, it is possible to configure a light emitting device or a light receiving device and connect them in cascade through individual guides. Configure output devices.

That is, one aspect of the present invention is to concentrate the conventional multiplexer/demultiplexer and distribute it to the signal module.As a means for realizing this, for example, the following method is used.

(i it) A method of using a light-emitting device and a light-receiving device in which a spectroscopic element that reflects or transmits wavelengths other than the emission wavelength of the light-emitting element and an element that does not have wavelength selectivity are combined and integrated.

(i) An optical transmission module that combines the light emitting or light receiving device described in (i)lii) above with an electrical conversion circuit, or an element without wavelength selectivity and a multiplexer/demultiplexer with an electrical conversion circuit. , a method using an optical receiver module.

It is clear that other methods can be considered by appropriately combining the three methods described above.

To show this specific configuration, the original communication light receiving or light emitting device of the present invention has a light receiving element or a light emitting element, an electrical signal input/output end thereof, an output light end, and an input light end, and the incident light An interference film filter is fixed at a predetermined position to reflect light other than a specific wavelength band of optical signals inputted from the end to the output light end, and the light receiving element or the light emitting element is fixed at a predetermined position. It is configured to receive or emit light of a specific wavelength through the .

(Function) Since the present invention is configured as explained above,
Assuming that the light wavelength characteristics of the interference film filter in the light receiving device and the light receiving/emitting device are the same for each light emitting device and the light receiving device, any channel can be created by vertically connecting these light receiving or light emitting devices according to the number of channels used. A multiplication table communication system can be configured depending on the number and wavelength used.

Therefore, it is extremely easy to change the system.

In other words, each light receiving or light emitting device operates so that only the light wavelength of the channel/channel that it shares is transmitted through the interference film filter, and other light wavelengths are reflected. A light-receiving or light-emitting element fixed at a predetermined position receives or emits only the corresponding wavelength of light to transmit a signal.

(Example) The present invention will be described in detail below based on an illustrated example.

FIG. 1 is a sectional view showing an embodiment of a light emitting device according to the present invention.

In the figure, 1 is a light emitting device according to the present invention.
An input light window hole and an output light window hole are provided at two adjacent apex corners of the rectangular parallelepiped housing 2 to reflect the multiplication table and condense the light onto the light projection lens 6, respectively. A light emitting element 10 such as a laser diode is arranged on an extension of the optical axis of the light emitting lens 6 toward the rear surface of the interference filter 9, and its electric signal input terminal 11? It is provided outside the housing 2. The input/output lenses 5 and 6 are provided with sleeves in the optical axis direction of the lenses to facilitate connection with the fiber guide.

Further, the interference film filter 9 has a characteristic of transmitting only light having the same wavelength as the light emitted by the light emitting element and reflecting light in other wavelength ranges.

FIG. 2 shows a light receiving device according to the present invention, which has the same structure as the output device shown in FIG. 1, but has the following differences:
Instead of the light emitting element 10, a light receiving element 121 such as an avalanche diode is positioned on the extension of the optical axis of the light receiving lens 30 toward the rear surface of the interference filter, and its electrical signal output end 13 is provided.
is provided outside the housing 2 as described above, and
The interference filter 5 has a characteristic of transmitting only light having the same wavelength as the light receiving wavelength of the light receiving element 12 and reflecting light of other wavelengths.

Since the present invention is constructed as described above, the optical signal of each device is inserted into the core part, and when an electric signal containing a signal to be transmitted is applied to the ten electric signal input terminals 11 by the nine light receiving lenses 5, the light signal is transmitted from the light emitting element. Since the light having a unique wavelength is emitted and is configured to pass through the interference filter, it is mixed with the above-mentioned emitted light and outputted to the outside from the emitting terminal.

Only the wavelength specific to the interference filter is transmitted through the interference filter, reaches the light receiving element 12, and outputs an electrical signal to its output terminal 13. Light other than this wavelength is reflected by the interference filter and output to the output terminal 4.
Output to the outside from.

FIG. 3 shows an example of configuring an optical communication system using the above-mentioned input/output devices, and the number of multiplexed channels is assumed to be four for ease of explanation. In other words, the wavelength of light used is 4
Although it is assumed that two channels are sent from the transmission device 14 to the opposing transmission device 15 and two channels are sent from the transmission device 15 to the transmission device 14, the actual transmission is determined based on the allowable transmission line loss, the sending level, and the allowable amount of crosstalk. The number of multiplexed channels and the transmission direction can be freely selected as long as the number of connected elements is within the insertion loss within the device.

In addition, as for the connection method of each device, the light emitting device 9 has its output light terminal facing the transmission line fa side, and the light receiving device has its input light terminal facing the transmission line side fa, and the light guides 16, 1, 6, . -・Knee...continues in cascade. 8λ1*8 in the transmission device 14
2! are each wavelength λ1. Light emitting device R according to the present invention that emits λ2.λ3. R1λ4 are respectively wavelengths λ3. λ4
This is a light receiving device according to the present invention which detects a light output terminal CNout and an input light terminal CN1n, which are connected in accordance with the above-mentioned conditions.

In addition, the final stage input/output device Sλ1.8λ− in each transmission device
4 is a connection terminal CNt 7 of each transmission device 14 and 15
, CN18'f: Connected to a transmission line, for example, an optical fiber fa.

Each light receiving device and light emitting device of the input/output section of the optical communication system connected in this way connects its electric signal input/output end to the input/output end of the signal processing devices 17 and 180, respectively, and sends necessary electrical signals to the light emitting device. All communication is performed by inputting the light into the light receiving device or deriving it from the light receiving device.

However, the present invention is not necessarily limited to the embodiments described above, and any shapes or combinations may be used as long as they are based on the same principle.

For example, in the above explanation, the interference film filter and the
,, 8th construction. Woyo 4-~1 month, 9e, 4゜8. “!
However, it is clear that the light emitting element may be one that does not have wavelength selectivity.

Furthermore, the structure and material of the spectral filter of the present invention.

The convergence method using the lens may be of a different type.

(Effects of the Invention) Since the present invention is configured and operated as explained above, there is no need for a unique multiplexer/demultiplexer determined by the number of channels and the optical wavelength used, which was conventionally required. In addition, the component occupancy rate of each input/output device can be reduced.

Furthermore, if overlapping wavelengths are not used for the two transmission lines, the order of cascade connection of these input/output devices can be set arbitrarily, and the number of channels and wavelengths used can be easily changed.

Furthermore, in the conventional n-channel multiplex communication system, 4 is n
In contrast, in order to multiplex channels, n+1 optical guides are required to connect the n elements to the multiplexer/demultiplexer and the multiplexer/demultiplexer to the transmission line.

According to this method, a light guide connecting n light emitting or light receiving devices is used to transmit n -1 light emitting or light receiving devices and the final stage light emitting or light receiving device;
It is sufficient to have a total of n light guides (one light guide connecting the paths) and the fiber wiring within the transmission device can be reduced. The input optical terminal is also used for optical processing adjustment of each light emitting or light receiving device.

The manufacturing cost can be reduced by simply using an output optical terminal, an element having wavelength selectivity, or a spectroscopic element and an element having no wavelength selectivity.

In addition, this method uses not only wavelength division multiplexing transmission, but also beam submultiplexing and
It is clear that the same effect can be obtained in the combination of optical transmission signals or bidirectional transmission using an optical directional coupler.9 The present invention reduces the cost of input/output devices in optical communication systems. It is extremely effective in achieving ease of use.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a light-emitting device according to the present invention, FIG. 2 is a cross-sectional view showing an example of a light-receiving device according to the present invention, and FIG. FIG. 1 is a block diagram showing an input/output section of an optical communication system using such a light receiving/emitting device. 1... Light emitting device according to the present invention. 7...Glass substrate, 8...
...Dielectric multilayer film, 9...Interference film filter. 10......Light emitting element, 11...
・・・・Electric signal input terminal, 12・・・・・・・・・
Light receiving element, 13... Electric signal output end, 14 and 15... Transmission device + fa in optical communication system Transmission line, SλI+Sλ2+”λ3 and Sλ4...
...Output device, R・λ1. R1λ2. R1λ
3 and R・λ4... Input device. Patent applicant: Toyo Tsushinki Co., Ltd. 11 bottles 1z1 ulcer

Claims (4)

[Claims] (1) In an input/output device used in an optical transmission system that multiplex transmits multiple modulated optical signals with different wavelengths in the same direction or in both directions on the same optical transmission path, the optical input end, output end, and electrical signal a light emitting element having an input end, and a predetermined interference film filter that reflects light incident from the input end to the output end or reflects light incident from the output end to the input end and transmits only light of a specific wavelength. 1. A light emitting device for optical communication, characterized in that the light emitting devices are fixed in position and positioned so that the light emitted by the light emitting devices passes through the interference film filter and is outputted to the light output end. (2) The light according to claim 1, wherein the light emitting element is a light receiving element, and is positioned on the axis of light that enters from the light input end and passes through the interference film filter. Communication light receiving device. (3) The light receiving system for optical communication according to claim (1) or (2), characterized in that a filter having a semi-transmissive characteristic for light in the entire wavelength range is used in place of the interference film filter; Light emitting device. (4) Claim (1) characterized in that the light receiving element or the light emitting element has optical wavelength selectivity;
The light receiving or light emitting device for optical communication according to (2) or (3).