JPS6364035A - Light wavelength converting circuit - Google Patents

Abstract

PURPOSE:To contrive a simplified constitution by making the modulated light having a second wavelength incident on a nonlinear optical element having a differential gain characteristic and modulating it with an optical signal having a first wavelength and using a light wavelength filter to take out only the light having the second wavelength of the output light. CONSTITUTION:The signal light having a wavelength lambda1 which is made incident on an end face 104 of a light wavelength filter 102 is emitted from an end face 106 and is made incident on an end face 107 of a nonlinear optical element 101. The modulated light having a wavelength lambda2 which is made incident on an end face 105 of the filter 102 is emitted from the end face 106 and is made incident on the end face 107 of the element 101. The light emitted from an end face 108 of the element 101 is made incident on an end face 109 of a light wavelength filter 103, and only the component having the wavelength lambda2 is emitted from the end face 101. Thus, the constitution is simplified and the light wavelength is converted on the level of light.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical wavelength conversion circuit used in a wavelength division optical exchange or the like.

(Prior art) Optical fiber transmission systems that use optical fibers as transmission paths have the advantages of being able to transmit a large amount of information because the optical fiber has a wide band, and that the optical fiber is not subject to induced noise. Therefore, it is expected that it will be widely used in the future. In addition to this optical fiber transmission system, it is desirable to use an optical switch that can exchange optical signals in the optical domain. As such an optical exchanger, a wavelength division optical exchanger described in Japanese Patent No. 57-079388 is known. In a wavelength-division optical switch, a communication channel is established between each wavelength of wavelength-multiplexed input and output optical signals, and switching is performed by converting the wavelengths. Therefore, an optical wavelength conversion circuit that converts the wavelength of the optical signal is essential. be. The conventional wavelength conversion circuit is the fifth
As shown in the figure, the input signal light of wavelength λ1 is sent to the light receiving element 50.
1 converts the electrical signal into an electrical signal, and converts the electrical signal into an electrical amplifier 50.
A light emitting element 503 whose output wavelength is λ2 after being amplified by 2
By driving the wavelength λ2, the wavelength is converted to λ2 and outputted.

(Problems to be Solved by the Invention) Currently, such wavelength conversion circuits have problems in that they are difficult to integrate, increase in scale, and are difficult to reduce cost due to the following reasons. In other words, light emitting elements and light receiving elements are made using InP-based materials, whereas electrical circuits such as electric amplifiers are made from Si or GaAs-based materials. Although it is possible to simplify the configuration of electrical circuits, which are inevitably complicated, by making them using InP-based materials, it is difficult to achieve high integration of electrical circuits using InP-based materials with current technology. .

An object of the present invention is to provide an optical wavelength conversion circuit having a simple configuration.

(Means for Solving the Problem) The optical wavelength conversion circuit provided by the present invention has a differential gain characteristic in the relationship between the amount of incident light and the transmittance, and has a differential gain characteristic in the relationship between the amount of incident light and the transmittance. a nonlinear optical element into which the modulated light of
The device is characterized in that it includes at least an optical wavelength filter that selectively extracts light having a wavelength of .

Furthermore, the optical wavelength conversion circuit provided by the present invention has a plurality of end faces, and modulated light of a first wavelength is inputted to the first end face, and the incident light amount and transmittance of the first end face and the second end face are determined. A nonlinear optical element having a differential gain characteristic in the relationship: the light incident on the first end face is emitted from the second end face but not the third end face, and the light incident on the second end face is emitted from the second end face. a directional optical element in which signal light of a second wavelength is emitted from the third end face and is incident on the first end face, and the second end face is in contact with the second end face of the nonlinear optical element; It is characterized by containing at least

(Function) In the present invention, the modulated light of the second wavelength is input to the nonlinear optical element having differential gain characteristics as described above, and is modulated by the optical signal of the first wavelength, so that the output light has the wavelength of Chinese cabbage 2. Only light is extracted using an optical wavelength filter or optical combiner.

Therefore, the present invention can provide a wavelength conversion circuit that has a simple configuration and directly converts optical wavelengths.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1, a signal light having a wavelength λ1 that is incident on the end face 104 of the optical wavelength filter 102 is emitted from the end face 106 and is made incident on the end face 107 of the nonlinear optical element 101. The modulated light of wavelength λ2 incident on the end face 105 of the optical wavelength filter 102 is also emitted from the end face 106 and passes through the nonlinear optical element 1.
The light is incident on the end face 107 of 01. Nonlinear optical element 101
The light emitted from the end face 10B is incident on the end face 109 of the optical wavelength filter 103, and only the component of wavelength λ2 is emitted from the end face 110.

FIG. 2 is a diagram for explaining the operation of the first embodiment of the present invention shown in FIG. 1, and shows the relationship between the amount of incident light and the transmittance of the nonlinear optical element 101. Nonlinear optical element 101
When the input light amount is O, the transmittance is also O, and when the input light amount is increased and exceeds P2, the transmittance changes from 0 to 1. It has a differential gain characteristic that rapidly increases up to . Of the light incident on the end face 107 of the nonlinear optical element 101 in FIG.
The light intensity of the modulated light component is set to P, which is smaller than P2, and the light intensity of the signal light component with wavelength λl is set to 0 at low level and P at high level, so that P, +P, is larger than P2. If the signal light with wavelength λ1 is at a low level, the input light amount of the nonlinear optical element 101 is Pl, so the output light amount is O1.If the signal light is at a high level, the input light amount is P.
, +P, >P2, so the transmittance is tl and the output light amount is t
, (P, +P3), so the level of the output light quantity also changes according to the binary level of the signal light of wavelength ^1. Therefore, if the wavelength λ2 component of the output light from the end face 108 is selected by the optical wavelength filter 103, modulated light having the wavelength λ2 and the same binary level information as the wavelength λl can be obtained, and from the wavelength ^l to the wavelength λ2. wavelength conversion can be performed.

There are various types of nonlinear optical element 101 having differential gain characteristics, such as one that utilizes a change in absorption characteristics of a multi-quantum well structure element due to input light, and one that utilizes a change in refractive index within an optical resonator due to input light. There are many elements based on this principle. Regarding changes in absorption characteristics of multi-quantum well structure elements depending on input light, see, for example, IEE, Journal of Quantum Electronics (IEE).
EJournal of Quantum Elec
tronics) Volume 20, Issue 3, Pages 265-2
On page 75, there is an Applied Physics Letter regarding changes in the refractive index within an optical cavity due to input light.
Lied Physics Letter) 46 (10
) volume May 15, 1985 issue pages 918 to 920
detailed on the page.

FIG. 3 is a diagram showing a second embodiment of the present invention, and the same numbers as in FIG. 1 represent the same components as in FIG. 1. In FIG. 3, the end face 3 of the optical wavelength filter 301
The optical signal having the wavelength λl incident on the nonlinear optical element 101 is emitted from the end face 303 and is incident on the end face 107 of the nonlinear optical element 101. On the other hand, the wavelength λ
Two modulated lights are incident. Here, if the light intensity of the modulated light of wavelength ^2 is set to P2 shown in FIG. The transmittance of the element 101 varies from O to 1 depending on the sum of the amounts of light incident on the end surfaces 107 and 10B.
It changes up to ゜. Therefore, the light having the wavelength λ2 that is incident from the end face 108 and emitted from the end face 107 is modulated by a change in transmittance according to the binary level of the signal light having the wavelength λ.

This modulated light of wavelength λ2 can be separated from the light incident on the end face 303 by the light wavelength filter 301 that outputs only the light of wavelength λ2 from the end face 304.

FIG. 4 is a diagram showing a third embodiment of the present invention, in which the same numbers as in FIG. 1 represent the same components as in FIG. The configuration is the same except for the one used.

In FIG. 4, the signal light with wavelength ^ is input to the end face 107 of the nonlinear optical element 101 via the optical combiner 402, and the modulated light with the wavelength λ2 is input to the end face 10B. Here, if the light intensity of the modulated light of wavelength λ2 is set to P2 shown in FIG.
The light of wavelength λ2 which enters from the sun and is emitted from the end face 187 is modulated according to the binary level of the signal light of wavelength λ.

This modulated light of wavelength λ2 is incident on the end face 406 of the light confluencer 402 and can be taken out from the end face 405.

Note that instead of the light combiner 402, an optical circulator or the like may be used in which the light incident on the end face 404 is emitted from the end face 406 but not from the end face 405, and the light incident on the end face 406 is emitted from the end face 405. A similar effect can be obtained.

(Effects of the Invention) As described above, according to the present invention, it is possible to obtain an optical wavelength conversion circuit that has a simple configuration and is capable of converting optical wavelengths at the optical level.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG. 2 is a diagram showing a first embodiment of the present invention.
3 is a diagram showing the second embodiment of the present invention, and FIG. 4 is a diagram showing the third embodiment of the present invention. , FIG. 5 is a diagram showing the configuration of a conventional optical wavelength conversion circuit. In the figure, 101 is a nonlinear optical element, 102.103
．． 301 is an optical wavelength filter, 402 is an optical combiner, 5
01 represents a light receiving element, 502 represents an electric amplifier, and 503 represents a light emitting element. Figure 2! ! ! ! ! grace

Claims (2)

[Claims] (1) A nonlinear optical element having a differential gain characteristic in the relationship between the amount of incident light and the transmittance, into which modulated signal light of a first wavelength and modulated light of a second wavelength are input; An optical wavelength conversion circuit comprising at least an optical wavelength filter that selects and extracts light of the second wavelength from the output light of the element. (2) It has a plurality of end faces, and modulated light of a first wavelength is input to the first end face, and the relationship between the amount of incident light and the transmittance of the first end face and the second end face has a differential gain characteristic. A nonlinear optical element, in which light incident on the first end face is emitted from the second end face but not emitted from the third end face, and light incident on the second end face is emitted from the third end face. A light comprising at least a directional optical element in which a signal light of a second wavelength is incident on the first end face, and the second end face is in contact with the second end face of the nonlinear optical element. Wavelength conversion circuit.