JPS58105129A - Optical amplifying circuit - Google Patents

Abstract

PURPOSE:To carry out amplification stably without using a Fabry-P erot resonator, by arranging a two-way 90 deg. polarizing rotator between two two-way light traveling wave amplifiers which have nonlinear saturation characteristics and dependency upon a plane of polarization, and arranging two polarization splitters on both sides. CONSTITUTION:This circuit has two-way light traveling wave amplifiers 10L and 10R which has nonlinara saturation characteristics and dependency upon a plane of polarization such as a solid-state laser crystal and a coloring matter laser medium. A two-way 90 deg. polarizing rotator 11 is arranged with said ampli- fiers 10L and 10R. Light A1 having orthogonal planes of polarization by the 1st and the 2nd polarization is caused to strike upon a polarization splitter 15L; and the 1st polarized wave A2 is amplified nonlinearly and output light A6 is emitted from a polarization splitter 15R. Similarly, output light B6 for input light B1 is obtained. This circuit constitution functions as a comparing circuit, waveform shaping circuit, and bistable circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical amplification circuit that nonlinearly amplifies an element without optical distortion.

Conventionally, as this kind of optical amplification circuit, as shown in Fig. 1, an oT
An optical nonlinear absorption medium such as w>v light absorber (e.g. Na
An optical nonlinear medium 1 made of a dispersive medium (such as C82, In8b, GaAs, etc.) whose refractive index nonlinearly changes depending on the light intensity is disposed, and a Fabry-Perot resonator 1L is disposed.
Based on the incidence of the light L1 on the Fabry-Perot resonator 11 (,
A configuration has been proposed in which light L2, which is a nonlinear amplification of light 1.1, is emitted.

However, in the case of such an optical amplification circuit, it is necessary to use Fabry-Perot resonators 1L and IR, and the optical Since the frequency of L1 is limited by the frequency specific to the optical nonlinear medium 1,
The disadvantage is that the light L2 obtained by nonlinearly amplifying the light L1 is extremely unstable.

Therefore, it is our intention to propose a novel optical amplification circuit of this kind that does not have these drawbacks, and this will become clear from what will be described below.

FIG. 2 shows an example of an element i1^ width circuit according to the present invention, -
It is constructed using an axial or biaxial solid-state laser crystal, a dye laser medium, an antireflection-treated semiconductor laser, etc., and has a nonlinear saturation characteristic in the optical amplification gain coefficient, which is known per se. First and second bidirectional optical traveling wave amplifiers having wavefront dependence (hereinafter referred to as optical amplifiers for simplicity)
It has 10L and 10R.

Between the optical amplifiers 10L and 10R, a bidirectional 90° polarization rotator-a (hereinafter referred to as a polarization rotator for simplicity) 11, which itself is well known, is arranged B7.

Also, on the opposite side of the polarization rotator 11 side of the optical amplifiers 10L and 10R, there are input terminals 12 and output terminals 13, which are known per se.
The first and second polarization splitters 15L and 15 having input and output terminals 14 are arranged in such a way that their inputs and outputs 414 are optical amplifiers 10L and 10R.

The above is an example of the configuration of the optical amplifier circuit according to the present invention. According to the configuration according to Jgi, the first and second
first and second planes of polarization (vertical and horizontal planes) of
or having a first polarization plane.
1 to the input end 12 of the polarization splitter 15L (as incident light), the polarized light output A2 having the first polarization plane can be split into the input/output end 14 of the polarization splitter 151, and the The polarized light output A2 is input to the optical amplifier 104 and is nonlinearly amplified.The polarized light output A2 is nonlinearly amplified by the optical amplifier 10L.

5 polarized light outputs A are obtained 7, and the polarized light output A3 is incident on the polarization rotator 11 by n1% from the polarization rotator 11.
Polarization plane! Ji Polarized light output A4 U5 having a second polarization plane (horizontal polarization plane) rotated by 90' from the polarization plane of Al.
Obtained nl, its polarization output A4 Ka SS beam width filter 10 f (,
is incident on r+, and is nonlinearly amplified by the optical amplifier 10L.
1. Nonlinear increase of polarized light output A4 by 1. Increased polarized light output A
5 is obtained, and its polarized light output A 5 b" enters the input/output end 14 of the 1m optical splitter 15 B. Therefore, the polarized light output A5 is outputted from the output end 13 of the polarized light splitter 15R as the output light A.
It is possible to emit light as 6.

In addition, the light B1 similar to the source A1 mentioned above is sent to the polarization splitter 15.
If the input light is made to enter the input end 12 of the polarization splitter 15R as an incident light, a polarized light output B2 having the first polarization plane can be obtained at the input/output end 14 of the polarization splitter 15R. 10R and is nonlinearly amplified.
A nonlinearly amplified polarized light output B5 of the polarized light output B2 is obtained from the optical amplifier 10R, and the polarized light output B5f)S is input to the polarization rotator 11, and the polarization plane is changed from the polarized light output B5 by the polarization rotator 11. A polarized light output B4 having a second polarization plane (horizontal polarization plane) rotated by 90° from the wavefront is obtained,
The polarized light output B4 is input to the optical amplifier 10L and nonlinearly amplified by n1%, and the polarized light output B5 is obtained by nonlinearly amplifying the polarized light output B4 from the optical amplifier 10L.
5 enters the input/output end 14 of the polarization splitter 15L, and therefore the polarization output B5 is input to the output end 15 of the polarization splitter 15L.
Since the optical amplifiers 10L and 10R have a nonlinear saturation characteristic in the optical amplification gain coefficient and n-wavefront dependence, the output light A1 and B1 can be emitted as the output light B6. The relative values of intensity are SA1 and SB, respectively.
Optical amplifiers 10L and 10 have input/output characteristics that make the relative values of the intensities of 1% output lights A6 and B6 SA6 and SB6, respectively.
The optical amplification gain coefficient g1 having the first polarization plane of R and the second
The optical amplification gain coefficient g2 with a polarization plane of gl/g
2 with r expressed as a parameter.

6S can be obtained as exhibiting nonlinear saturation hysteresis characteristics as shown in FIG. 5A, B, 0, and D. However, the input/output characteristics in FIG. 5A-D are for input light B1.
The case where the relative value of the intensity SB is constant is shown.

Therefore, according to the configuration of the optical amplifier circuit according to the present invention shown in FIG. 2, the input light B1 is a repetitive pulse whose relative intensity value SB1 is less than a constant value, as shown in FIG. Synchronize input light A1 with input light B1 in this case,
When it is assumed that the relative value 5A1bS of one intensity is a repetitive pulse that sequentially takes different values as shown in FIG. 4B, the output output light A6 is the relative value of the intensity of the human power light A1 as shown in FIG. When SA is smaller than the relative value SB1 of the intensity of the input light B1, the relative value SA6 of the intensity is a substantially constant value that is almost unrelated to the magnitude of the input light B1. 13S, and vice versa, the relative value S of the intensity can be obtained almost independently of its magnitude.
A6 can be obtained as having a significantly small and almost constant value, and the output light B6 can be obtained as shown in the fourth diagram, when the relative value of the intensity SB6 is 6 to the output light. can be obtained as exhibiting an inverse relationship. Incidentally, FIGS. 4C and 4D show the results when the above-mentioned value of F was set to 0.5.

Therefore, the configuration of the optical amplifier circuit according to the present invention shown in FIG. 2 can function as a comparison circuit.

Further, according to the configuration of the optical amplifier circuit according to the present invention shown in FIG. 2, the input light A1 shown in FIG.

When the output light A6 is assumed to have a gentle waveform,
It can be obtained as having a steep waveform, and the sixth
As shown in the figure, when the human power light A1 has a narrow and gradual waveform, the output light A6 can be obtained as having a wide waveform, and thus functions as a waveform shaping circuit. It is something that can be done. However, in FIGS. 5 and 6, the value of F mentioned above is set to 0.5.

3 Also, the results are shown when the relative value SB of the intensity of the input light B1 is set to 1×10.

Further, according to the configuration of the optical amplification circuit according to the present invention shown in FIG. 2, the input light A1 is alternately changed into two relative intensity values SA1, large and small, as shown in FIG. 6A. When it is assumed that the pulse is a repetitive pulse, the output light A6 is changed as shown in FIG. , the relative value of the intensity SA6 can be obtained as a significantly smaller, almost constant value, and when the relative value of the intensity SA1 reaches a value of ``dog,'' the next value becomes the first smaller value. Until this happens, the relative value SA6 of the intensity can be obtained as a significantly large and approximately constant value, and furthermore, the output light B6 can be
As shown in FIG. 6 O, the relative value SB6 of the intensity is the output light A6.
It is possible to obtain a circuit that exhibits the opposite relationship to that in the case of , and therefore it is possible to obtain a function equivalent to a bistable circuit. In addition, Fig. 6 B and C are.

The results are shown when the value of F mentioned above is 0.5 and the relative value SB1 of the intensity of the input light B1 is 1×10 2 .

Therefore, according to the configuration of the optical amplifier circuit according to the present invention shown in FIG. 2, it is possible to obtain the functions as the comparison circuit, waveform shaping circuit, and bistable circuit described above, and it will be clear from the above. Although a detailed explanation will be omitted for the sake of clarity, by changing the value of r described above, light other than the input lights A1 and B1 described above can be made to enter either or both of the polarization splitters 15L and 15ft as bias light. This device (0) has the great feature of being able to function as various nonlinear amplifier circuits such as limiters and logic circuits. Moreover, such a function hS has an extremely simple configuration using only two optical amplifiers IDL and 10, one polarization rotator 11, and two polarization splitters 15L and 15R.
In addition, unlike the conventional case shown in FIG. 1, it is possible to obtain stable operation without using Fabry-Perot resonators facing each other, and without causing unstable operation due to changes in the resonator length. It has the characteristics of a dog.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional optical 1-width circuit, Fig. 2 is a system diagram showing an example of an optical amplification circuit according to the present invention, Fig. 6 is a curve diagram showing input/output characteristics, and Fig. 4 A-0. FIG. 5, FIG. 6, and FIG. 7 A, 0 are waveform diagrams for explaining the present invention. In the figure, 10L and 101 (represent bidirectional optical traveling wave amplifiers,
11 is a bidirectional 90° polarization rotator, 12 is an input end, 13
14 is an output end, 14 is an input/output end, and 15L and 15R are polarization splitters, respectively. (10) Figure 3 A = SA. No. 31゛・<A f3 A1 Figure 3C No. 4 :;41″, First D A1 Procedural Amendment (Method) April 30, 1980 Mr. Haruki Shimada, Commissioner of the Patent Office (:,.) 1- 1. Indication of the case 1982 Patent Application No. 204032 2. Name of the invention Optical deck circuit 3. Person making the amendment Relationship to the case Patent applicant 8. Contents of the amendment (1) 1.β Specification, No. 10 On page 14 line [41st IA]
-0, J should be corrected as “Figure 4 A-D, J. Above (2)

Claims (1)

[Claims] first and second bidirectional optical traveling wave amplifiers having a nonlinear saturation characteristic and n-wavefront dependence in the optical amplification gain coefficient; A bidirectional 90° polarization rotator f's is disposed on the side opposite to the bidirectional 90° polarization rotator side of the first and second bidirectional optical traveling wave amplifiers. first and second polarization splitters having an end and an input/output end are disposed in such a manner that the input/output ends thereof are on the side of the first and second bidirectional optical traveling wave amplifiers, respectively; An optical amplification circuit characterized by: