JPH0223732A - Optical communication system - Google Patents

Abstract

PURPOSE:To reduce cost and power consumption by connecting the station of subscriber system communication and the outside of a subscriber by means of an optical fiber transmitting a signal with a prescribed wave length, and providing a secondary higher harmonic generation means which inputs the signal of the prescribed wave length to the termination part of the fiber and outputs the signal of the prescribed wave length when the subscriber receives the signal outside. CONSTITUTION:When the station and the subscriber are connected by the optical fiber, and the transmitted signal is received by a subscriber indoor plastic fiber, the secondary higher harmonic generation means 500 is added and connected to the terminal which is positioned in the outside of the optical fiber for transmission. Here, the means 500 is constituted by a crystal generating a secondary higher harmonic, and it changes the optical signal with the wave length of lambda=1.3m, which is transmitted from the single mode optical fiber, for example, into the wave length of lambda=0.6-0.7mum by using the plastic fiber with satisfactory transmission loss characteristic for reception through the use of the non-linear characteristic.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to provide an optical communication system for subscriber systems using optical fibers, which is low in cost and low in power consumption. In a subscriber system in which an optical fiber that transmits a signal at a predetermined wavelength is used to connect a station and a subscriber's outdoors, and a plastic fiber is used to receive the signal inside the subscriber's house, a predetermined A second harmonic generating means is added which outputs a second harmonic of a predetermined wavelength when a signal with a wavelength of The harmonic output is configured to be incident on the plastic fiber.

[Industrial application field]

The present invention relates to an improvement in a subscriber system optical communication system using optical fibers.

At this time, there is a demand for an optical communication system that is low in cost and low in power consumption.

[Conventional technology]

FIG. 4 is a diagram showing the relationship between wavelength and transmission loss of an example of a plastic fiber.

FIG. 5 is a diagram showing the configuration of a conventional example.

When information such as images and data is exchanged between the information center connected to the exchange and each home using a subscriber system that connects the exchange (hereinafter referred to as the exchange) and each home, the system shown in Figure 5 As shown, the station and each home are connected by, for example, a single mode optical fiber, and an optical signal having a wavelength (λ) of, for example, 1.3 μm is used.

Although optical fibers are used indoors as they have the advantage of being non-inductive, plastic fibers are used because of their safety, ease of handling, cost, etc. However, since the plastic fiber has a large transmission loss at a long wavelength of 1.3 μm and hardly passes it, the optical signal from the single mode fiber is first received by a light receiving element such as the PIN diode 1 and converted into an electrical signal.

Then, indoors, as shown in Figure 4, the wavelength range (0.6 to 0.7
A light-emitting element that emits light in μm), such as a light-emitting diode (
(hereinafter referred to as LED) 2 or the like is used, and the LED is modulated by the electrical signal and input into the plastic fiber. and P connected to the other end of the plastic fiber.
The signal is converted back into an electrical signal by the TN diode 3 and received by a terminal device (not shown) or the like.

In this way, necessary information was obtained from, for example, an information center.

[Problem to be solved by the invention]

However, the above-described configuration requires an extra light emitting element and a receiving circuit, resulting in an increase in cost and power consumption.

Therefore, it is an object of the present invention to provide an optical communication system with lower cost and lower power consumption.

[Means to solve the problem]

The above problem is solved by the configuration shown in FIG.

In other words, in Fig. 1, an optical fiber that transmits signals at a predetermined wavelength is used to connect the subscriber communications station and the subscriber's outdoors.
In subscriber systems that use plastic fibers to receive data indoors, 500 is added to the outdoor end of the optical fiber, and when a signal of a predetermined wavelength is input, the second harmonic of the predetermined wavelength is output. This is second harmonic generation means.

One end of a plastic fiber is connected to the output part of the second harmonic generation means, so that the second harmonic output is input to the plastic fiber.

[For production]

In FIG. 1, in the second harmonic generation means 500,
When a signal of a predetermined wavelength is input, a second harmonic of a predetermined wavelength is output. One end of a plastic fiber is connected to the output part of the second harmonic generation means, so that the second harmonic output is input to the plastic fiber.

As a result, data can be transmitted using a plastic fiber with low transmission loss in the second harmonic region without using extra light emitting elements or receiving circuits, making it possible to achieve lower costs and lower power consumption.

〔Example〕

FIG. 2 is a diagram showing the configuration of an embodiment of the present invention.

FIG. 3 is a diagram explaining the operation of the SHG crystal used in the example.

The same reference numerals refer to the same objects throughout the design.

As shown in FIG.
By using the nonlinear characteristics of the cs GenerBtor crystal (hereinafter referred to as 5) IG crystal), the long wavelength (5) transmitted from the single mode optical fiber shown in Fig.
For example, an optical signal of λ = 1.3 μm is transferred to a wavelength range (λ-06 to 0) where plastic fiber has good transmission loss characteristics.
．． 7 μm).

As a result, PIN diode 1 and LED in the case of the conventional example
There is no need to use the second etc., making it possible to reduce costs and power consumption.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize an optical communication system with lower cost and lower power consumption.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of the present invention, Fig. 2 is a diagram showing the configuration of an embodiment of the invention, Fig. 3 is a diagram explaining the operation of the SHG crystal used in the embodiment, and Fig. 4 is an example. FIG. 5 is a diagram showing the relationship between the wavelength and transmission loss of a plastic fiber. FIG. 5 is a diagram showing the configuration of a conventional example. In the figure, 500 indicates second harmonic generation means.

Claims (1)

[Claims] A subscriber system that connects a subscriber communications station and a subscriber's outdoors using an optical fiber that transmits a signal at a predetermined wavelength, and receives the signal inside the subscriber's house using a plastic fiber. 2, which outputs a second harmonic of a predetermined wavelength when a signal of the predetermined wavelength is input to the outdoor terminal end of the optical fiber.
A second harmonic generation means (500) is added, and one end of the plastic fiber is connected to the output part of the second harmonic generation means, so that the second harmonic output is input to the plastic fiber. An optical communication system characterized by