JPS5817737A - Multiplex light source - Google Patents

Abstract

PURPOSE:To prevent the error from disclosing at existing/spare device switching, by providing a delay circuit for one of existing or spare laser light sources and compensating the shift in arrival time of an optical signal at the reception side caused by the difference of center illumination wave length of the laser light sources. CONSTITUTION:A semiconductor laser LD1 is driven with a driving circuit DR1 and an optical output P1 is transmitted to an optical fiber via a photo switch PS. If the arrival time of the optical output of the laser LD1 is lower than that of a laser LD2, the output of the driving circuit DR2 is given to the laser LD2 via a delay circuit DL for driving. Thus, the output P1 of the laser LD1 and the output P2 of the laser LD2 are transmitted via the photoswitch PS, although the timing of the output is shifted, they can be reached to the reception side with coincidence.

Description

[Detailed description of the invention] The present invention is effective when switching between the current and standby light sources.

This invention relates to a multiplexed light source that prevents errors from occurring on the receiving side.

In optical communication systems, multiplexing of light sources has been conventionally performed to improve the reliability of light sources.

-Example #! Shown in Figure 1.

In the figure, the semiconductor laser LD1 is first connected to the drive circuit DR.
The optical output Pt is sent to the optical fiber F via the optical switch P8.

When deterioration of the semiconductor laser LDI is detected, the semiconductor lasers I and D2 are driven by the drive circuit 'DR2, and then the optical outputs P, P! are combined and sent to a single fiber 7.

At this time, the original switch ps is P, +P, =P,
Gradually increase the ratio of P while keeping it constant.

As a result, the reception@RIO can receive optical signals without causing instantaneous signal interruption. However, semiconductor laser L
If the center emission wavelengths of Dl and LD2 are different, the receiver R
In EO, due to wavelength dispersion of optical fiber F, St and 8f
As shown, the signal arrival time deviates by T, and due to this deviation, Pl and P.

When the signals are synthesized and output, the signal waveform deteriorates and errors occur.

The purpose of the present invention is to eliminate such shortcomings, and the purpose is to have a working light source and a spare light source, and to drive the light source when the working light source deteriorates and causes a cough. In a multiplexed light source, a delay circuit is provided in the drive circuit of at least one of the working or standby light sources, and the arrival time of the optical signal at reception caused by the difference between the center emission waves of the working and standby light sources is determined. The multiplexed light source is configured to compensate for the deviation of the light source by delaying the drive signal of the light source using the delay circuit. .

The present invention will be explained in detail below based on an embodiment.0 Fig. 2 is a diagram showing an embodiment of the present invention, where DL is a delay circuit, and the same members as in Fig. 1 are designated by the same reference numerals. It is attached.

In the present invention, the deviation in the arrival time of the signal is compensated for by shifting the drive timing, and for this purpose, the output signal of the drive circuit DR2 is delayed by the delay circuit DL as shown in FIG.

As a result, the output timings of the optical outputs P and P are shifted, but they reach the receiving side at the same time.

In the example shown in the figure, the optical output of the semiconductor laser LDI is delayed in arrival time compared to the optical output of the LD2.

When there is a drop, a delay circuit DL is provided at the output stage of the drive circuit DRI.

FIG. 3 shows another embodiment of the present invention, in which VDL is a delay circuit whose delay time is variable, DOCIN is a delay control circuit, ExC is a switching control path, and bvx.

DV2 is a splitter, and 5PEI and 5PE2 are spectrometers.

The same members as in FIG. 2 are given the same reference numerals.

In the example shown in the figure, when the semiconductor laser LDI deteriorates, the switching control circuit KXC also drives the drive circuit DR2, and the branching circuit DV
Part of the optical output PI + Pt is branched by I and DV2 and input to spectrometers 5PEI and 8Pff12, respectively.

The spectrometers spmx and 5pz2 detect the center axis wavelength, and based on this, delay control 111!21 [・C
ON changes the delay time of the delay circuit VDL.

As described above, according to the present invention, there is no deviation in arrival time, so no errors occur during switching.

[Brief explanation of the drawing]

FIG. 1 shows a nine-m1 system using conventional multiplexed light sources, and FIGS. 2 and 3 show embodiments of the present invention. FIG. In the figure, DRI, Dft, 2 are drive circuits, LDI, LD2 are semiconductor lasers, ps is an optical switch, DL, VDL are delay circuits, DVI, DV2 are branchers, 8'pH. 5PE2 is a spectrometer, D CON is a delay control circuit, wx
c is a switching control circuit.

Claims (1)

[Claims] In a multiplexed light source that has a working light source and a backup light source and drives the backup light source when the working light source deteriorates, a delay circuit is provided in the drive circuit of at least one of the working light source or the backup light source. A multiplexing system is provided to compensate for the difference in the arrival time of the original signal at the receiver 91111 caused by the difference in the center emission wavelength of the active and standby light sources by delaying the drive signal of the light source in the delay path. light source.