JPH084759Y2 - Optical fiber repeater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical fiber repeater for converting an optical signal into an electric signal and performing relay amplification in an optical communication system using an optical fiber.

<Prior art> Generally, in optical fiber communication, an optical signal transmitted by an optical fiber is converted into an electrical signal at intervals of about several tens of km, relayed and amplified, and then converted into an optical signal again for transmission. An optical fiber repeater is provided.

As shown in FIG. 3, this optical fiber repeater basically has an O / E converter 1 for converting an optical signal into an electric signal and a rounding of the waveform of the electric signal from the O / E converter 1. That is, a timing correction circuit (C1ock Recovery Circuit) 2 that removes jitter (time-axis fluctuation), and a timing without rounding based on the corrected signal and the electrical signal from the O / E converter 1. There is provided a selection circuit 3 for reproducing an electric signal that has been affected, and an E / O converter 4 for converting the electric signal from the selection circuit 3 into an optical signal again.

Then, the time correction circuit 2 is provided with a narrow-band timing filter 5 _0, the narrow-band timing filter 5 _0, high selectivity and low loss, i.e., having a high filter quality factor Q is required It

Conventionally, as the narrowband timing filter 5 _0, 1
SAW (surface acoustic wave) filter is used up to GHz,
In the frequency band higher than that, a dielectric resonator is often used.

<Problems to be solved by the invention> However, if a narrow band and low loss filter is to be realized by a dielectric resonator, the size must be increased and integration is not easy. ,
There is a problem that it is difficult to miniaturize and integrate the optical fiber repeater.

The present invention has been made in view of the above points,
The purpose is to facilitate miniaturization and integration of an optical fiber repeater.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention includes a time correction circuit including a narrow band timing filter, converts an optical signal from an optical fiber into an electric signal and amplifies it. In the optical fiber repeater for removing jitter by the time correction circuit, the narrow band timing filter is composed of an active filter including a microwave resonator and an amplification feedback circuit for compensating for the loss of the microwave resonator. .

<Operation> According to the above configuration, since the narrow band timing filter is configured by the active filter for the microwave band, a filter having a high filter sharpness Q can be realized in a smaller size than the conventional dielectric resonator. At the same time, integration becomes possible.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an optical fiber repeater according to an embodiment of the present invention, and portions corresponding to the conventional example of FIG. 3 are designated by the same reference numerals.

This optical fiber repeater also corrects the rounding of the waveform of the electric signal from the O / E converter 1 that converts an optical signal into an electric signal, that is, the jitter ( Time correction circuit (C1ock Re)
covery Circuit) 2 and this corrected signal and O / E
Based on the electric signal from the converter 1, a selection circuit 3 that reproduces an electric signal with a rounded timing and an E / that converts the electric signal from the selection circuit 3 into an optical signal again
And an O converter 4.

In this embodiment, the narrow band timing filter of the time correction circuit 2 is constituted by the active filter 5 in order to enable downsizing and integration of the optical fiber repeater.

FIG. 2 is an equivalent circuit diagram of the active filter 5.

The active filter 5 includes a microwave resonator 6
And an amplification feedback circuit 7 for canceling the insertion loss in the microwave resonator 6 and increasing the filter sharpness Q. The amplification feedback circuit 7 includes a phase adjustment circuit 8 and an amplification circuit 9. And is connected to the microwave resonator 6 by electric field coupling via the capacitive element C1. Further, C2 is a capacitive element for electric field coupling with a circuit (not shown) in the front and rear stages.

In the active filter 5, the output from the microwave resonator 6 is supplied to the amplification feedback circuit 7 and amplified, and the phase is adjusted so as to be in phase with the microwave resonator 6 (an integral multiple of 2π). By feeding back to the microwave resonator 6, the insertion loss of the microwave resonator 6 is compensated and the filter sharpness Q is increased.

As a result, it is possible to realize a filter having a low loss and a narrow band, and it is easy to achieve miniaturization and integration as compared with a conventional example using a dielectric resonator as a narrow band timing filter.

<Advantages of Device> As described above, according to the present invention, the narrow band timing filter of the time correction circuit is an active filter including a microwave resonator and an amplification feedback circuit for compensating for the loss of the microwave resonator. Since it is configured, the optical fiber repeater can be easily downsized and integrated as compared with the conventional example using the dielectric resonator.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG. 2 is a first diagram.
FIG. 3 is an equivalent circuit diagram of the active filter shown in FIG. 3, and FIG. 3 is a schematic configuration diagram of a conventional example. 2 ... Time correction circuit, 5 ... Active filter (narrow band timing filter), 6 ... Microwave resonator, 7
...... Amplification feedback circuit.

Claims (1)

[Scope of utility model registration request] 1. An optical fiber repeater comprising a time correction circuit including a narrow band timing filter, converting an optical signal from an optical fiber into an electric signal for amplification, and removing jitter by the time correction circuit. An optical fiber repeater, wherein the timing filter comprises an active filter including a microwave resonator and an amplification feedback circuit for compensating for the loss of the microwave resonator.