JPH01134431A - Optical signal switching device - Google Patents

Abstract

PURPOSE:To easily switch an optical signal with time by setting timing pulses of respective currents implanted in optical bistable semiconductor lasers which are cascaded optically. CONSTITUTION:A multiplex input optical signal which is propagated in a fiber FI is entered into the bistable semiconductor lasers (BLD) 101-104 through a branching element 60. At such a time, when currents I11-I14 are turned on in synchronism with the input signal, the BLDs 101-104 operate as gates which enter respective channel signals into BLDs 201-204. When currents I21-I24 are turned on at the same time, the respective input signals are stored temporarily in the BLDs 201-204 and when currents I31-I34 are applied to the BLDs 301-304, the stored signals are read out according to the order. For the purpose, the order of reading is changed to rearrange the optical signals. Consequently, the multichannel optical signal can be switched with low loss and small leakage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device that performs time-division switching of optical signals.

(Points to be Solved by the Prior Art and the Invention) As a method for time-divisionally switching optical signals, for example, a configuration as shown in FIG. 4(a) is known. In the figure (showing a 4-bit example), 1 is an optical switching section, 2 and 3 are spatial optical switches, 4 is an optical memory, and F! and FO are the original fibers. Fiber F! The time-multiplexed optical signals inputted from the spatial optical switch 2 are stored for one frame period in the optical memory 4 for each channel by the spatial optical switch 2, and the signals are switched by changing the order of output by the spatial optical switch 3. be exposed. The multiplexed optical signal with the signals exchanged between channels propagates through the optical fiber FO. FIG. 4(b) shows the above in more detail, showing an optical waveguide 5.0 made on a LiNbO3 substrate.
5' constitutes a spatial optical switch 2.3.

A voltage is applied to the electrode 6 placed on the waveguide through a control line 7, and the signal from the optical fiber FI is distributed to the optical fibers F1 to F4 for each channel. fiber F1
The light propagated through F4 is temporarily stored in bistable semiconductor lasers LDI to LD4 via lens 9. The storage state is determined by applying a voltage to the electrode 6' of the spatial optical switch 3 via the control line τ, and after changing the reading order, an optical signal is emitted to the optical fiber FO.

However, with this method, the optical loss as a device is large due to the loss of the waveguide serving as a space switch and the connection loss between the fiber and the waveguide, etc., and it is difficult to line up a large number of waveguides, so it is difficult to manufacture multiple channels. There were problems such as a decrease in SN due to leakage between waveguides.

(Objective of the Invention) The present invention was proposed against this background, and an object of the present invention is to provide a small switching device that performs switching with low loss and small leakage for multi-channel optical signals. With the goal.

(Means for Solving the Problems) The optical switching device of the present invention, which was proposed to solve the above object, includes an optical branching element and a plurality of cascade-connected twins arranged for each branch. a stable semiconductor laser, an optical isolator and lens disposed between each of the bistable semiconductor lasers, and an optical coupler that optically couples the cascaded subsequent bistable semiconductor laser;
and a control section that supplies a control current to the bistable semiconductor laser.

(Example〕 Next, examples of the present invention will be described.

It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements may be made without departing from the spirit of the present invention.

FIG. 1 is a block diagram of an embodiment of an optical switching device according to the present invention (four channels as an example). In the figure, 10 is an optical switching section, 20 is a control section, and FI and FO are on the input side and output side, respectively. Optical fiber, 101-104
, 201-204° 301-304 are bistable semiconductor lasers, 11-14. 11'-14', 21-24.21
'~2a, 31~34. 31'~34' are electrodes of those bistable semiconductor lasers, 40 is an optical isolator, 50
60 is a lens, 60 is an optical branching element, and 7o is an optical coupler. Thus, the light from the optical fiber FI is branched by an optical branching element 60 and given to bistable semiconductor lasers 101 to 104 via a lens 5°. For example, the light emitted from the bistable semiconductor laser 101 passes through the lens 50, the optical isolator 40° lens 50, and the bistable semiconductor laser 201.
, lens 50, optical isolator 40, lens 50. The bistable semiconductor laser 301 enters the optical coupler 70 via the lens 5o, and the light that has entered the other bistable semiconductor lasers 102 to 104 in this way also enters the optical coupler 0, and then to the optical fiber FO. will be output.

Figure 2 ((A) is an example of a bistable semiconductor laser (hereinafter referred to as B).
(abbreviated as LD)) 101, 201, and 301 are shown. Also, (/1) shows the optical input/output characteristics of each bistable semiconductor laser.Bistable semiconductor laser 1
01 to 104 and 301 to 304 have threshold characteristics as shown in FIG. 2(c), and bistable semiconductor lasers 20
1 to 204 are set to have bistable characteristics as shown in FIG. 2(b). In other words, the current flowing through the two electrodes 11 and 11' of the BLD 1010! 1. .

l'1. and 1'1. By setting 111 to an appropriate value and setting the current of 111 to a large value (in the case of "11"!H), the optical output can have a threshold characteristic with respect to the optical input, as shown in the figure. That is, it oscillates when light above a certain threshold is input, and does not oscillate below that. Also,
When 111 is small, no oscillation occurs even if the optical input is large.

The BLD 301 is also set to have similar threshold characteristics.

On the other hand, regarding the optical input and output characteristics of BLD 201,
LD 2010 The current flowing through the two electrodes 21 and 21' is 21 e I'21, and I'2. is set to an appropriate value and the current of I21 is set to a large value (I2.==
In the case of I), as shown in the figure, the optical output can be made to have bistability with respect to the optical input. In other words, if light exceeding a certain threshold is input, BLD will occur even if the light input is turned off.
201 continues to output light. Moreover, when the current of X21 is made small (in the case of !2.÷!1), no light is output even if there is light input.

Under the above operating conditions, a current is applied to each BLD via the control line at the timing shown in FIG. 3 in synchronization with the multiplexed optical input signal. In this example, signals are exchanged as follows: CHI →'CH3 CH2 → CHI CH3 → CH2 CH4 → CH4.

In FIG. 1, the multiplexed input optical signal propagated through the fiber FI is sent to each BLD 101 to 1 by a branching element 60.
It is incident on 04. At this time! 11~I,, When turned on in synchronization with i input signals CHI~CH4, BLD 1
01 to 104 are BLD 2 for each channel signal.
It acts as a dart that is incident on 01 to 204. at the same time! 2. ~t2,1 When turned on, each input signal of CHI to CH4 is temporarily stored in BI and D 201 to 204, respectively. Next, 151-I5. BLD 301~30
4, the stored signals can be read out in accordance with the order. The read optical signals are combined by the optical fiber 0 to become a multiplexed signal with the channels swapped, and propagate through the fiber FO. That is,
In the above process, BLDs 101 to 104 are write darts, BLDs 201 to 204 are optical memories, and BLs are
D 301 to 304 act as readout r-), and by changing the readout order, the optical signals are replaced.

(Effects of the Invention) As described above, according to the present invention, the timing/base pulse of each current injected into optically cascaded optical bistable semiconductor lasers can be set.

Temporal switching of optical signals can be easily performed. In addition, since it can be made into a small module, it is easy to handle, and has advantages such as high-speed switching, amplification function, and no decay wave, so it can be used as a high-performance optical signal processing device in optical communication such as a high-speed optical switching device. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of cascade connection of bistable semiconductor lasers according to the present invention and each setting operation, and FIG. 3 is a diagram showing an embodiment of the bistable semiconductor laser according to the present invention. A diagram showing the timing of control/9 pulses to the semiconductor laser,
FIG. 4 shows a conventional example. FO, FI...Optical fiber, 1... Original switching unit, 2.3... Space optical switch, 4... Original memory,
5.5'...LINbO, optical waveguide, 6.6'...
Electrode, 7゜1... Control line, LDI ~ LD4...
Bistable semiconductor laser, 8,8'...electrode, 9,
9'... Lens, 10... Switching section, 20.
...Control unit, 101~104°201~204, 30
1-304... Bistable semiconductor laser, 11-14
, 11'~14', 21~24°21'~24'
, 31-34, 31'-34'...electrode, 40.
... Optical isolator, 50... Lens, 70... Optical splitter, 60... Optical branching element.

Claims (2)

[Claims] (1) An optical branching element, a plurality of cascade-connected bistable semiconductor lasers arranged for each branch, an optical isolator and lens arranged between each of the bistable semiconductor lasers, and a cascade-connected rear stage An optical signal switching device comprising: an optical coupler for optically coupling bistable semiconductor lasers; and a control section for supplying a control current to the bistable semiconductor lasers. (2) Consisting of a plurality of three cascade-connected bistable semiconductor lasers arranged in parallel, the first bistable semiconductor laser has threshold characteristics, and the second bistable semiconductor laser has bistable Claim 1, characterized in that the third bistable semiconductor laser has a threshold characteristic, and is configured such that independent currents are applied to the electrodes of each bistable semiconductor laser. The optical signal switching device described.