JP3062750B1 - Wavelength converter - Google Patents

Abstract

An object of the present invention is to provide a wavelength conversion device that has a small number of light sources, is efficient, does not require large millimeter-wave power, and has good linearity. SOLUTION: A ground electrode layer 5 is formed below a substrate 4 having an electro-optical effect, and two input paths 1 and 2 for guiding input light to one end of the upper surface of the substrate 4; A waveguide 6 having two output paths 7 and 8 for guiding output light to an end of the substrate 4 is formed at a substantially central portion of the upper surface of the substrate 4, and an electrode for forming a microstrip line is formed on an upper layer of the substrate 4. A part of the electrode has an interdigital electrode structure in the upper layer of the waveguide, and one end of the electrode is short-circuited to the ground electrode layer 5, and furthermore, the millimeter wave voltage is
And between the interdigital electrode 3, two input paths 1
Input light from any one of
Changes the traveling direction and the wavelength, and as a result, the two output paths 7
And 8, light whose wavelength has been converted can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wavelength converter, and more particularly, to a wavelength multiplex communication (Wav) having good efficiency.
election Division Multiple
The present invention relates to an optical wavelength device that can be used in a switch for xing (hereinafter simply referred to as WDM), and more particularly to a wavelength converter that forms a wavelength conversion circuit used in a wavelength multiplexing cross-connect.

[0002]

2. Description of the Related Art JP-A-10-221725 discloses that
In order to obtain a wavelength conversion circuit used in WDM cross-connects in large-capacity network communications, an optical semiconductor device that integrates a semiconductor gain section and a spot size conversion section is optically coupled to a silica-based planar optical waveguide and mounted. Hybrid Michelson interference wavelength conversion circuit,
One optical path of the Michelson interference system is constituted by an optical waveguide circuit optically coupled to an optical semiconductor element in which the semiconductor gain section and the spot size conversion section are integrated, and the other circuit of the Michelson interference system is an optical waveguide circuit. It is disclosed that it is constituted only by the above.

In order to obtain an optical transmission system for optically controlling the amplification of an optical fiber amplifier, Japanese Patent Application Laid-Open No. Hei 5-181176 discloses a laser active material and a pump light having a first wavelength λ1. An optical system comprising an optical amplifier including one laser 1 and means for coupling light of a second wavelength λ2 to the optical amplifier, further comprising a third laser for generating light at a third wavelength λ3. The light is coupled to the optical amplifier by a coupler, and the wavelength λ3 of the light generated by the wavelength λ3 of the light generated by the third laser 3 is the amplification of the light of the second wavelength λ2 based on the pump light. Is selected such that it can be controlled as a function of its intensity, the optical transmission system comprising a frequency converter for converting an input signal of the third wavelength λ3 into an optical signal of the second wavelength λ2. Device It is disclosed that it can function as

Further, according to "Applied Optics" edited by Ichiro Yamaguchi, edited by the Japan Society of Applied Physics, pp. 217-219, Ohmsha Publishing Co., Ltd., Chapter 7 in 1998. When ultrasonic waves propagate through transparent liquids or solids, the density changes due to the sound pressure and the refractive index changes, forming a phase grating.The pitch of this grating is equal to the wavelength of the ultrasonic waves and moves at the speed of sound. Further, the phenomenon that light is diffracted by this grating is referred to as an acousto-optic effect (aco
This is referred to as “usto-optic-effect”, and one example of the diffraction is Bragg diffraction. One example of the application is to change the frequency of the ultrasonic wave to change the wavelength of the light diffracted in a certain direction. It is stated that the wavelength can be tuned rapidly.

[0005] However, the above-mentioned conventional method has a problem that the former method requires a plurality of light sources, is inefficient, has poor linearity, and distorts the signal waveform. The latter method has a problem that there is an upper limit to the frequency of the ultrasonic wave, and it is difficult to realize a large wavelength change.

The present invention has been made in view of the above problems, and has a small number of light sources, is efficient, does not require large millimeter-wave power, has good linearity, and has a good signal waveform. It is an object of the present invention to provide a wavelength conversion device that does not cause distortion and has a large wavelength change amount.

[0007]

According to the present invention, a ground electrode layer is formed below a substrate having an electro-optical effect, and input light is applied to one end of the upper surface of the substrate. A waveguide having two input paths for guiding light and two output paths for guiding output light to the other end of the upper surface of the substrate is formed substantially at the center of the upper surface of the substrate, and further comprises a microstrip line. An electrode is formed on the upper layer of the substrate, a part of the electrode has an interdigitated electrode structure in an upper layer of the waveguide, and one end of the electrode is short-circuited to a ground electrode layer. I have.

Further, the present invention is characterized in that, in the above, a buffer layer made of a low refractive index material for preventing light leakage is provided on the upper layer of the substrate.

Further, the present invention is characterized in that, in the above, a layer for adjusting the impedance of a millimeter wave circuit made of a low refractive index material is provided between the substrate and the ground electrode.

Further, the present invention is characterized in that, in the above, the substrate is made of LiNbO ₃ .

Further, the present invention is characterized in that, in the above, both terminals electrically connected to the millimeter wave source are formed at the center end of the ground electrode layer formed below the substrate and at the center end of the cross electrode. ,

Further, according to the present invention, when a millimeter-wave voltage is applied between the ground electrode layer and the interdigital electrode, the input light input from one of the two input paths is changed to the interdigital electrode. , The traveling direction and the wavelength are changed, and as a result, wavelength-converted light is obtained from one of the two output paths.

The interdigital electrode used as a component of the present invention is described in "Microwave Integrated Circuit" by Yoshihiro Konishi, 5
According to the (2) interdigital capacitor in the hybrid integrated circuit, Chapter 2 in 1973, Sanpo Publishing Co., Ltd., the capacitor having the structure in which the dielectric is sandwiched between the upper and lower electrodes is compared with the microstrip circuit. This has the advantage that the size can be remarkably saved, but it also has the disadvantage that when it is added to a thin-film microstrip circuit, the manufacturing procedure becomes complicated. Although it occupies a relatively large area, it has the advantage that it can be easily configured with the same processing means required for forming a general thin film microstrip circuit.

According to the present invention, when a millimeter-wave signal is input to an intersecting electrode provided on an optical waveguide structure made of a material having an electro-optic effect and input light is diffracted, the diffracted light is more millimeter than the input light. Since the frequency is shifted by the frequency of the wave signal, wavelength conversion can be realized. Also,
The present invention has a resonance structure including the inductance of the microstrip line between the short-circuit point with the ground electrode and the interdigital electrode and the capacitance of the interdigital electrode. It is possible to perform wavelength conversion with high efficiency.

In short, the features of the present invention do not require a separate light source, and theoretically enable wavelength conversion with zero loss of input light, and the conversion accuracy is the accuracy of the frequency of the modulated signal. It depends on the current technology, but it is 50-100
It is possible to obtain a very high-precision wavelength converter with a millimeter-wave oscillator of about GHz, and furthermore, if the resonance structure which is a component of the present invention is used, efficient wavelength conversion can be performed with a small millimeter-wave output. It becomes possible.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. FIG. 1 is a perspective view of a wavelength converter according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a first input path;
Is the second input path, 3 is the interdigital electrode, 4 is LiNbO
_{3 is a} substrate, 5 is a ground electrode layer, 6 is a Ti waveguide,
7 is the first output path, 8 is the second output path, and 9 and 10
Indicates terminals electrically connected to the millimeter wave source.

In an embodiment of the present invention, a wavelength converter of 50 GHz will be described as an example. As shown in FIG. 1, when a millimeter-wave voltage at 50 GHz is applied between the ground electrode layer 5 and the interdigital electrode 3, the input light input from the first input path 1 changes to the portion of the interdigital electrode 3. Then, the traveling direction and the wavelength of the input light are changed, and as a result, the wavelength-converted light can be obtained from the second output path 8.

On the other hand, when the above-mentioned millimeter-wave voltage is not applied, the input light is emitted from the first output path 7 without being changed in wavelength.

In the embodiment of the present invention, the wavelength converter of 50 GHz has been described as an example, but as described above,
With a millimeter-wave oscillator in the range of about 50 to 100 GHz, it is possible to obtain a wavelength converter having very high accuracy.

[0020]

According to the wavelength conversion device of the present invention, there are provided two input paths for forming a ground electrode layer below a substrate having an electro-optic effect and guiding input light to one end of the upper surface of the substrate. A waveguide having two output paths for guiding output light to the other end of the upper surface of the substrate is formed at a substantially central portion of the upper surface of the substrate, and an electrode for forming a microstrip line is formed on an upper layer of the substrate. Since part of the electrode has an interdigital electrode structure in the upper layer of the waveguide, and one end of the electrode is short-circuited to the ground electrode layer, the following effects are obtained. (1) Highly efficient wavelength conversion is possible without impairing the input signal. (2) Since the output side does not include the wavelength component on the input side, a filter required for removing the wavelength component is usually unnecessary. (3) Since modulation is performed by an electric signal, it is possible to control the wavelength on the output side with very high accuracy. (4) Since wavelength conversion is performed without converting an optical signal into an electric signal, it is suitable for high-speed communication. (5) The attenuation of the optical signal can be kept very small.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 first input path 2 second input path 3 interdigital electrode 4 LiNbO ₃ substrate 5 ground electrode layer 6 Ti waveguide 7 first output path 8 second output path 9 terminal electrically connected to millimeter wave source 10 mm Terminal electrically connected to the wave source

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 2/02 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A ground electrode layer is formed below a substrate having an electro-optic effect, and two input paths for guiding input light to one end of an upper surface of the substrate; A waveguide having two output paths for guiding output light is formed at a substantially central portion of the upper surface of the substrate, and an electrode for forming a microstrip line is formed on an upper layer of the substrate. An interdigital electrode structure in the upper layer of the waveguide, and one end of an electrode formed in the upper layer of the substrate;
Part is short-circuited to the ground electrode,
Of the microstrip line between
Resonance Structure Consisting of Capacitors and Interdigitated Electrodes
In the electrode formed in the upper layer of the substrate
Between the side not shorted to the ground electrode and the ground electrode
A wavelength converter characterized in that a millimeter-wave voltage is applied therebetween. 2. A 請 characterized by having a buffer layer for preventing light leakage of a low refractive index material on the substrate layer
The wavelength converter according to claim 1 . 3. A serial to have a layer for EP dancing adjustment of millimeter wave circuit made of a low refractive index material to claim 1 or claim 2, wherein between the substrate and the ground electrode
Wavelength conversion apparatus mounting. 4. The wavelength converter according to claim 1, wherein said substrate is made of LiNbO ₃ .