JPS60212726A - Optical pulse generating device and optical pulse train generating device - Google Patents

Abstract

PURPOSE:To obtain an optical pulse of a high speed without losing interferability by using interferential property of laser light and a time delay of the laser light caused by an optical path difference. CONSTITUTION:Laser light which has been made incident from a light input optical path 1 is branched by a half mirror 5, and divided into the first optical path 2 and the second optical path 3. The first optical path is reflected by total reflecting mirrors 7-9, and thereafter, reflected by a half mirror 10 and outputted to a light output optical path 4, and light passing through the second optical path 3 is reflected by a mirror 6, and thereafter, passes through a phase impedance matching box 11, passes through the half mirror 10 and it is outputted to the light output optical path 4. In this case, the output optical path 4 adjusts in advance the phase impedance matching box 11 and an attenuator 12 so that outputs of the first optical path 2 and the second optical path 3 negate mutually and no output is generated. When the waveform of the first optical path 2 and the waveform of the second optical path 3 are superposed, an output by the light output optical path 4 becomes ''0'', and it is ''0'' when the light input is ''0'', therefore, the light output is generated to the light output optical path 4 only when one optical waveform of the optical path 2 or the optical path 3 is outputted.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a light pulse generator.

Conventional configurations and their problems Conventional methods for generating single pulses include: (1) Chopper control (2) Laser oscillation control using a Q-switch (2) Direct current control of a semiconductor laser.

Method (1) is a method of mechanically blocking the source or electrically deflecting the light using ultrasonic diffraction, etc., but the pulse speed is on the order of several μs to several ms, and the high-speed source is There was a problem that pulses could not be generated.

Methods (1) and (2) are methods in which laser oscillation is directly controlled, and have the disadvantage of generating high-speed optical pulses of several ps to several ns.

OBJECTS OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide an optical pulse generator and an optical pulse train generator that can generate high-speed optical pulses without losing coherence.

Structure of the Invention The present invention provides a means for branching a laser beam into two optical paths, a means for recombining the two optical paths into one optical path, and a means for changing the optical path lengths of the two optical paths depending on a desired pulse width. The structure is characterized by having means for changing the phase of the branched laser beam in one of the two optical paths, and a means for changing the phase of the branched laser beam in one of the two optical paths. It is possible to generate original pulses.

The present invention also provides a configuration in which a plurality of the above-mentioned optical pulse generators are arranged, and a means for branching one laser beam into the arrangement of the above-mentioned optical pulse generators with different optical path lengths and inputting the optical pulses. and means for combining a plurality of optical pulses emitted from the array of generators into one optical path.

It is possible to generate a high-speed optical pulse train without losing coherence.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows the configuration of an optical pulse generator according to a first embodiment of the present invention. In the numbers in Figure 1, 1 is the optical input optical path of the laser beam, 2 is the branched first optical path, 3 is the branched second optical path, 4 is the optical path of the recombined optical output, 6,
10 is a half mirror 16, 8 and 9 are total reflection mirrors,
11 is a phase matching device that controls the phase of light in the second optical path;
2 is a light attenuator. In addition, in Figure 1, H and M are total reflection mirrors, H and M are half mirrors, 1P is a phase matching device, 1 is an attenuator, l is the length of the optical path, and the fear of 21 is the first one. It means the optical path difference between the optical path and the second optical path.

FIG. 2 shows optical pulse waveforms in each optical path during operation in the first embodiment of the present invention.

The operation of the first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The laser light incident from the optical input optical path 1 passes through the half mirror 5.
The optical path is divided into a first optical path 2 and a second optical path 3. The first optical path is reflected by the total reflection mirrors 7.8 and 9, then reflected by the half mirror 1o, and outputted to the optical output optical path 4. Further, the light passing through the second optical path 3 is reflected by the mirror 6, passes through the phase matching device 11, passes through the half mirror 10, and is output to the optical output optical path 4. At this time, in the optical output optical path 4, the phase matching device 11 and the attenuator 12 are adjusted so that the outputs of the first optical path 2 and the second optical path 3 cancel each other out and there is no output. The optical waveform at the end of each optical path based on the optical input waveform shown in FIG. 2 (1) is shown in (li), OiD, 4v). When the waveform of the first optical path 2 and the waveform of the second optical path 3 overlap, the output on the optical output optical path 4 becomes O. Also, the optical input is 0
Since the optical output is 0 at 0 o'clock, the optical output is output to the optical output optical path 4 only when the optical waveform of either the optical path 2 or the optical path 3 is output.

As a result, the optical output waveform for the optical input waveform shown in FIG. 2(1) becomes as shown in (V). The time axis shift in each figure is the time required for light propagation, and is a value determined from the optical path length. At this time, the pulse width t of the optical output waveform.

is the value determined by the optical path difference (24) between the first optical path 2 and the second optical path 3, to = (26) 10 (c is the speed of light) -... -
It has the relationship (1). It can be seen from equation (1) that by arbitrarily selecting the value of (21), an optical output with an arbitrary pulse width can be obtained. For example, if it is 24230(α), a pulse width of tl)=1 (nS) is obtained. Further, pulses are generated corresponding to the rise and fall of the optical input waveform.

It should be noted that a conventional slow pulse generation method may be used as the optical input pulse source, but other methods may be used as long as coherence is not lost. The phase matching device 11 may be one that obtains an optical phase difference by applying an electric field to a ferroelectric material such as KDP or LiNb05. Other methods can also be used in the same way. Further, the phase matching device 11 and the attenuator 12 may be provided in either the first optical path 2 or the second optical path 3.

FIG. 3 is an example when the optical input waveform is not rectangular. Light operates on the same principle as shown in Figure 2.

An optical output waveform shown by l1v)VC is obtained for the original input waveform shown in FIG. 3(1). Pulse width tOU optical path length difference (2e)
This value is determined by , and the waveform is shaped. Since the triangular light output of qψ has a weak light intensity, it can be selectively removed by electrical signal processing. At this time, the optical output waveform is shaped by the rise shape of the optical input waveform. Contrary to FIG. 3, when the optical input waveform rises slowly and falls quickly, the optical output waveform produces a triangular optical output and then an optical pulse with a pulse width of to. At this time as well, since the light intensity of the triangular light output becomes weak, it is only necessary to selectively remove it.

FIG. 4 shows the configuration of an optical pulse generator according to a second embodiment of the present invention. Hereinafter, parts that are the same as those already described will be described using the same numbers. In the numbers in FIG. 4, 1 is the optical input optical path of the laser beam, 2 is the branched first optical path, and 3 is the branched second optical path.

4 is the optical path of the recombined optical output, 6p, 7 is a total reflection mirror, %6 is a half mirror, and 111 is a phase matching device.

12 is an attenuator.

The optical input of the laser beam incident from the optical input optical path 1 is divided into a first optical path 2 and a second optical path 3 by a half mirror 5 [, and then reflected by total reflection mirrors 6 and 7 and combined again. The light is output to the optical path 4. By adjusting the phase matching device 11 and the attenuator 12 in advance, the same operation as in the first embodiment can be obtained. The same applies to the optical output waveforms for each original input waveform shown in FIGS. 2 and 3.

FIG. 6 shows the configuration of an optical pulse train generator according to a third embodiment of the present invention, which is monolithically integrated using a waveguide structure. In the numbers in FIG. 5, 1 is the optical input optical path of the laser beam, 2 is the branched first optical path, and 3 is the branched second optical path.

4 is an optical path for the recombined optical output, 13 is a darating that reflects a part of the optical power, 14fift is a grating that reflects all of the power, 7' is a phase matching device, 8
' is an attenuator %; 16 is a cleavage plane or a grating that reflects all of the optical power; and 16 is a dielectric or semiconductor substrate.

The operation of the device is exactly the same as in the second embodiment, and similar effects can be obtained.

The gratings 13 and 14 have a period determined according to the wavelength of the laser beam, and are made using a change in refractive index or the like. The phase matching device 7' changes the refractive index by applying an electric field to a portion of the substrate 16. The substrate 16 is made of a dielectric or semiconductor material, and has a structure in which the refractive index of the surface is higher than the refractive index of the inside of the substrate, so that laser light can be guided through the substrate surface.

According to the embodiments described above, high-speed optical pulses can be generated without loss of coherence.

The structure of the original pulse train generator according to the fourth embodiment of the present invention is shown in FIG. 6 for ease of explanation.

The explanation will be given using the example of the optical waveform shown in FIG.

In FIG. 6, 20 is the original input optical path, 30 is the optical output optical path, and 21+221 417 42)S-7 min-.

231 43 is a total reflection mirror, 31.32 is the 1st degree 2.
3 is an optical pulse generator according to the third embodiment.

Although FIG. 6 shows an example using n optical pulse generators, the figure numbers are omitted to simplify the explanation.

The n optical pulse generators are manufactured with the same configuration, and the width of the optical pulse is 1. It is set to . When the optical input waveform of FIG. 7 (1) enters the original input optical path 1 of FIG. 6, the optical output waveform of each pulse generator is as shown in FIG. 7 (++), OiD
, 4V), as shown in M. The value of the interval t1 between the original pulses at this time is determined by the difference in the optical path length between each device, which is the sum of the optical path length until the original input enters each party pulse generator and the optical path length until the optical output is emitted. This is a determined value, and when the optical path length difference is L, the optical pulse interval t1 is given by t1=L/C (O is the speed of light).

FIG. 7(v) shows the optical signal waveform in the optical output optical path 30, and n original pulse trains can be obtained by combining n original pulse generators with respect to the step-like original input waveform.

In the description of this embodiment, a configuration in which a plurality of optical pulse generators are arranged in parallel has been described, but the same effect can be obtained even in a configuration in which optical pulse train generators and optical pulse generators are connected in series in multiple stages. Needless to say.

Effects of the Invention As described above, the present invention achieves the effect of obtaining high-speed optical pulses without losing coherence by using the coherence of laser light and the time delay of laser light due to the optical path difference. This makes it possible to realize an excellent optical pulse generator and optical pulse train generator that can perform the following.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of the optical pulse generator, and FIGS. 2 and 3 are optical input response comparison diagrams. 4 and 6 are block diagrams of a 21st third embodiment of the optical pulse generator, respectively, and FIG. 6 is a block diagram of the first embodiment of the optical pulse train generator. FIG. 7 is a comparison diagram of optical input response. 1... Light input optical path, 2... First optical path %3... Second optical path, 4... Group optical output optical path,
5, 1o... half mirror, 6, 7, s, 9.
...Total reflection mirror. 11... Phase matching device, 12... Attenuator, 2o... Optical input optical path, 3o... Old... Optical output optical path, 21 H22r41.42... Group/half mirror. −
%23.43... Total reflection mirror, 31.32.
...Light pulse generator. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure Light Input Arrow R Power II Figure Exaggeration Figure 3 Figure 4 Figure 5 Light Input Figure 6 Light Input Maruta Power

Claims (1)

[Claims] (1) means for branching the laser beam into two optical paths;
means for recombining two optical paths into one optical path; The method includes means for varying the optical path lengths of the two optical paths according to a desired pulse width, and means for changing the phase of one of the branched laser beams in one of the two optical paths. Characteristics of the original pulse generator. (O) A means for branching a laser beam into two optical paths, a means for combining the two optical paths into one optical path again, a means for varying the optical path length of the two optical paths according to a desired pulse width, It has a configuration in which a plurality of optical pulse generators each having a means for changing the phase of one of the branched laser beams is arranged in one of the two optical paths, and one laser beam is used to generate the optical pulse. An optical pulse train generator characterized by having means for branching and inputting optical path lengths to an array of the apparatus and means for combining a plurality of optical pulses emitted from the array of optical pulse generators into one optical path. .