JPS61157128A - Device for multiplexing and separating high speed optical pulse - Google Patents

Abstract

PURPOSE:To attain multiplexing and separation of an ultrahigh speed light pulse signal by using a switch control pulse signal to control adjacent light switches in a cross type switch and decreasing the width of the switch control pulse signal less than the difference between an optical pulse propagating time and a pulse delay time. CONSTITUTION:An output light guide path 20 connecting light switches 41, 42 and light switches 42, 43 is constituted by an optical fiber whose length is adjusted to form the optical pulse propagating time between the light switches to be 1ns, a control line 30 includes delay lines 31, 32 to give a prescribed delay to an electric signal and it is designed that a pulse delay time 1.833ns is given between the adjacent light switches. A period of the switching control pulse signal is 2.5ns and the pulse width is 0.4/ns. The light pulse signal given to input light guide paths 11, 12, 13 is nearly synchronized with the switch control pulse signal at the light switches 41, 42, 43 and its pulse width is nearly 0.5ns.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a device for multiplexing or separating high-speed optical pulses used for high-speed signal transmission. Since the commercialization of semiconductor lasers capable of high efficiency, the field of application of optical communications using semiconductor lasers as a light source has rapidly expanded.However, in the direct modulation of semiconductor lasers, the upper limit of the modulation speed is the lifetime of the injected carriers. 9.5
It is also possible to obtain optical pulses with a narrow pulse width of around 0 ps, but in this case too, due to the influence of the long lifetime of the injected carriers, a change in the response depending on the pulse pattern, the so-called pattern effect, occurs, so the speed corresponding to the minimum pulse width is low. For example, it is difficult to conduct one optical signal at 20 Gb/s for a width of 50 ps. On the other hand, a method using a high-speed external modulator has been proposed, but in order to amplify the high-speed random pulse signal and drive the modulator, in addition to a wide-band pulse amplifier, it is necessary to use a wide-band flatness as the frequency characteristic of the modulator. However, in practice, it is difficult to operate at speeds of several Gb/s or higher. As another conventional example, a method is known in which a plurality of independent optical signal sources having low speed but narrow pulse width are combined in parallel by an optical multiplexer to obtain a high-speed optical pulse signal. However, this method has the disadvantage that unless the synchronization jitter between the optical signal sources is kept small, interference occurs between adjacent pulses, making it difficult to increase the speed.
Another disadvantage is that the upper limit of the signal speed is limited by the pulse width of the light source. Furthermore, when the optical waveguide is a single mode system, there is a drawback that the multiplexing loss tends to be large.

(Object of the Invention) The object of the present invention is to eliminate the above-mentioned drawbacks and to provide high-speed optical pulse multiplexing and demultiplexing that enables ultra-high-speed optical pulse signal multiplexing or demultiplexing.
According to the present invention, in a high-speed optical pulse multiplexing/separating device including a plurality of series-connected crossover type optical switches, the optical switches are connected to each other. Adjacent optical switches are controlled by an opening/closing control pulse signal having a pulse delay time different from the optical pulse propagation time between the optical switches, and the width of the opening/closing control pulse signal is the difference between the optical pulse propagation time and the pulse delay time. A high-speed optical pulse multiplexing/demultiplexing device characterized by being smaller than t is obtained.

(Example) Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a first embodiment based on the present invention. This embodiment shows cross-type optical switches 41, 42, 43, . . . connected in series. Output optical waveguide 20 connecting these
．． Input optical waveguides 11, 12, 13, and optical switches 41, 42, . . . are connected to optical switches 41, 42, 43, respectively.
As the zero optical switches 41, 42, and 43, which are composed of the control line 30 for transmitting the opening/closing control pulse signals 43, a directional coupling type optical switch formed on a LiNbO5 electro-optic crystal or the like is used. The coupling state between the input optical waveguides 11, 12, 13 and the output optical waveguide 20 is controlled by the electric signal. The output optical waveguide 20 connecting the optical switches 41 and 42 and between the optical switches 42 and 43 is composed of an optical fiber whose length is adjusted so that the optical pulse propagation time between the optical switches is Ins, The control line 30 is a delay line for giving a certain delay to an electric signal.
The repetition period of the mouth opening/closing control pulse signal, which is designed to provide a pulse delay time of 1.833 nst between adjacent optical switches, is 2.5.
The pulse width is 0.4/ns. input optical waveguide 11,
The optical pulse signals given to 12.13 (respectively input signals #1. +zt - #3) are connected to optical switches 41.42
．． 43 are almost synchronized with the opening/closing control pulse signal, and the pulse width thereof is approximately 0.5 ns.

Figure 3 is an operational diagram of this embodiment.B Each input signal is multiplexed so that the interval is the difference between the optical pulse propagation time and the delay time of the opening/closing control pulse signal.According to this embodiment While the optical pulse signal input by the previous stage optical switch is passing through each optical switch section, the switch is in the open state and is output as is to the output optical waveguide 20, and the optical pulse signal and the optical pulse signal inputted by the optical switch section are inserted. Mutual interference with the optical pulse signal generated does not occur. The interval between optical pulse signals inserted and multiplexed in adjacent optical switch units is determined by the difference between the optical pulse propagation time and the pulse delay time of the switching control pulse signal, so it is extremely stable and eliminates relative jitter due to sb multiplexing. It is possible to prevent the amount from increasing. Since the optical pulse signal width after multiplexing is determined by the switching control pulse signal, it contributes to the waveform shaping of each input signal and to the reduction of mutual jitter at the same time.

In this embodiment, three human signals with a bit rate of 400 Mb/s are multiplexed to obtain a signal of 1.2 Gb/s.

FIG. 2 is a diagram showing a second embodiment based on the present invention. This embodiment is similar to the first embodiment except that it is constructed in an integrated manner on a GaAs semiconductor substrate. Some 0
An n-type AJ' is placed on an n-type GaAa substrate with a (100) orientation.
o, aGag, 7Ali (lx 10 cIn
Si-doped (2 μm thick), n-type GaAs (I
8i doped with X I O 15 cm, thickness 0.1 μm
), p-type AjO, 30a. , 7AS (2X10 o
n Be-doped, 1 μm thick)'t-t-sequential epitaxial, p-type Aj. , 30a. , yAS layer into a ridge waveguide shape, the input optical waveguides 11, 12, 13 . Output optical waveguides 20° optical switches 41, 42, 43 are formed.

The ridge waveguide width is 2 μm, the waveguide spacing in the optical switch section is 1 μm, the coupling length is 1 mm, and each optical switch 41
．． 42.43 is 10 mm (light pulse propagation time approximately 100 pS). The control line 30 is p-type Aj
The parts other than the optical switch section are formed of Au wiring via 5i02 on the 3Gao, 3Gao, and yAs layers.

By inserting delay lines 31 and 32 between optical switches 41 and 42 and 42 and 43, a pulse delay time of approximately 200 ps, which is 100 ps larger than the above-mentioned optical pulse propagation time, can be achieved.
I am getting s.

In this embodiment, input signal #1. #2. 1.3μ as #3
Input all signals with m wavelength and bit rate of 2 Gb/s,
Repeatedly 500 ps as opening/closing control pulse signal.

A pulse with a width of 50 ps was used. This will result in 6 Gb/
In the configuration of the embodiment in which s multiplexed optical pulse signals can be obtained, by increasing the number of input terminals, it is possible to obtain 5
/s is possible. Since the optical switch section, which is the insertion point of the optical pulse signal, is connected in series, there is little bending in the leading wavepath section when segmenting as in this example, and it is also possible to use an optical multiplexer when there is a large number of multiplexed signals. The advantage is that there is less problem of multiplexing loss.

Incidentally, in the above-mentioned embodiments, a configuration having an optical multiplexing function was described, but if the input and output are reversed and a switching control pulse signal synchronized with the input optical pulse signal is used, the optical pulses separated at each party switch section can be used. It goes without saying that signals can be obtained (effects of the invention).Finally, to summarize the effects of the present invention, it is possible to multiplex or separate ultra-high-speed optical pulse signals with less pulse jitter and pulse pattern effects. be.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing the configurations of first and second embodiments, respectively, based on the present invention. FIG. 3 is an operational diagram of the first embodiment. In FIG. 3, 11°12.13 is an input optical waveguide, and 20 is an output optical waveguide. 30 is a control line, and 41, 42, and 43 are optical switches. 71 Figure II 1213 Human-powered optical waveguide? ! 20 Deba leading waveguide 30 control line 41.42.43 Optical switch 72 Figure 111213 Manual optical waveguide 20 Output optical waveguide 30 Control line

Claims (1)

[Claims] A plurality of cross-type optical switches connected in series, the optical switches adjacent to each other of the optical switches have a pulse delay time different from the optical pulse propagation time between the optical switches, and the width of the opening/closing control pulse signal is A high-speed optical pulse multiplexing and demultiplexing device comprising means for applying a switching control pulse signal smaller than the difference between the optical pulse propagation time and the pulse delay time.