JPS63266430A - Optical harmonic generator - Google Patents

Abstract

PURPOSE:To obtain stable higher harmonic output light by providing an optical coupling part on a substrate on which a waveguide type harmonic generation part is formed and projecting laser light to said part. CONSTITUTION:Light guides 2, 3 are formed on the substrate 1 consisting of a single crystal such as LiNbO3. A prism 4 is disposed as the optical coupling part in tight contact with one end of the substrate 1. The laser light 5 is projected through the prism 4 to the waveguide 2 in this constitution. Combshaped electrodes 6 output a surface acoustic wave 7 according to the high frequency impressed thereto an change the refractive index of the substrate 1. Zero-order different light A and 1st-order diffracted light B are thereby generated from the laser light 5. The diffracted light B enters the waveguide 3 from a lens 9 thereafter and generates second-order higher harmonics C. The higher harmonics C are phase-matched within the substrate 1 and are outputted in said direction. the stable higher harmonic light is thus obtd. and the need for adjustment such as intricate positioning is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical harmonic generation device, and more particularly to an optical harmonic generation device used for wavelength conversion of laser light.

(Background of the invention) Laser light is used for writing, reading, and measuring information.

It is becoming widely used in various fields such as processing.

However, the wavelength of laser light that can be used is often restricted depending on each field, and the applications of laser oscillators are limited, or laser light of the desired wavelength cannot be obtained.
In many cases, the desired performance as R1 cannot be obtained.

Therefore, it has been proposed to convert the wavelength of laser light using nonlinear optical effects to obtain laser light of a desired wavelength.

For example, in Hitotsubashi's optical wavelength converter,
There is one described in Publication No. 94031. The converter uses 1-iNbo3 as a substrate, and a part of it
An optical waveguide with a high refractive index is formed by exchanging + with H÷ by an ion exchange method. The leading waveguide portion formed in this way is resistant to optical damage and can confine optical energy at high density. When converting the wavelength of laser light, the maximum nonlinear constant of LiNbOs is used,
By establishing phase matching between the waveguide mode of the fundamental wave and the substrate radiation mode of the harmonic, the second harmonic component is radiated into the substrate.

(Problem to be solved by the invention) However, the end area of the optical input part of such an optical wavelength converter is quite small, for example, about 2 μw + xo, 4 μm, and the optical system focuses the laser light and makes it incident. A highly accurate optical system is required, and position adjustment also requires advanced technology. When in use, it is easily affected by vibrations, dust, etc., and it is difficult to obtain stable output light.

Furthermore, when performing information processing using laser light, it is necessary to modulate the intensity of the laser light. Such optical modulators include acousto-optic devices (AOMs) and electro-optic devices (
EOM) etc. are used. However, if an attempt is made to use a combination of individually constructed optical modulators and optical wavelength converters, it is difficult to downsize, the cost increases, and the adjustment of the optical system becomes complicated.

On the other hand, when using a semiconductor laser as a laser light source, the semiconductor laser itself can be directly modulated by the drive current, but the oscillation wavelength and output are likely to become unstable due to oscillation mode popping and the influence of returned light. It is difficult to obtain stable modulated output.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to realize an optical harmonic generation device that can easily input a laser beam and obtain stable harmonic output light.

(Means for Solving the Problems) The present invention, which solves the above problems, includes at least a waveguide type optical harmonic generation section and a laser beam applied to the waveguide type optical harmonic generation section on a common substrate. It is characterized in that it is integrated with an optical coupling part for inputting light.

<Function> According to the optical harmonic generation device of the present invention, an optical coupling part for inputting laser light into the waveguide type optical harmonic generation part is provided on the substrate on which the waveguide type optical harmonic generation part is formed. , the incident area of the laser beam is much wider than before, the precision of the focusing optical system is relatively low, positioning is relatively easy, and stable output is achieved. You can get light.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes a substrate made of, for example, a single crystal of 1iNbo3, and optical waveguides 2.
3 is formed. These leading waveguides 2.3 are connected to the substrate 1
It is formed by covering the unnecessary portions with, for example, an aluminum mask, immersing them in benzoic acid, and heating them, so that l−i+ in the exposed portions is converted to H+. 4 is a prism used as an optical coupling part for making the laser beam 5 enter the leading waveguide 2 on the surface of the substrate 1;
v! on one end side of the surface of Placed in 5th place. A comb-shaped electrode 6 forms a surface acoustic wave device used as an optical modulation section, and is formed by sputtering, for example, to generate a surface acoustic wave 7 on the surface of the optical waveguide 2 in a direction substantially perpendicular to the traveling direction of the laser beam 5. formed by. 8 comb-shaped electrode 7
This is a high frequency TA source for driving the oscilloscope, and is connected to the comb-shaped electrode 7. Reference numeral 9 denotes a lens for condensing the output light of the optical modulation section and inputting it into the optical waveguide 3 used as an optical harmonic generation section, and this embodiment shows an example in which a Lunebourg lens is used.

The operation of the device configured in this way will be explained.

Laser light 5 is incident on leading waveguide 2 via prism 4 . On the other hand, focusing on a surface acoustic wave device used as an optical modulation section, a traveling wave of ultrasonic waves, that is, a surface acoustic wave 7 is outputted in accordance with a high frequency signal applied to a comb-shaped electrode 6, and the refraction of the crystal of the substrate 1 Vary the rate. This results in
A grating will be formed in the leading waveguide 2. When the laser beam 5 passes through the grating, Bragg diffraction acts, and the 0th-order diffraction light A and the 1st-order diffraction light B
occurs. Here, the intensity of the diffracted light can be modulated by adjusting the power of the high-frequency signal applied to the comb-shaped electrode 6, and the diffraction angle can be changed by adjusting the frequency of the high-frequency signal. In other words, by adjusting the high-frequency signal, it is possible to modulate not only the laser light (
, it is also possible to change the position of the laser beam focused on the optical waveguide 3. In the leading waveguide 3, second-order higher dimming C of the first-order diffracted light B of the incident laser light is generated. The phase matching of the second-order harmonic dimming C is achieved within the substrate 1 having a certain angle with respect to the fundamental wave, and output as the second-order harmonic dimming C in that direction.

With this configuration, the input positional accuracy of the laser beam 5 can be considerably relaxed compared to the conventional one, and it is less susceptible to the effects of dust adhesion and vibration, and stable output light can be obtained.

Furthermore, as in the above embodiment, the light modulation section can be integrated on the substrate 1, thereby making it possible to reduce the size and cost of the entire VT device and eliminate the need for complicated positioning and other adjustments. be able to. Here, since the conversion efficiency to the second harmonic is proportional to the square of the input light intensity, by providing the optical modulation section before the optical harmonic generation section as in the above embodiment, the modulation degree can be amplified by the square. Therefore, an improvement in modulation efficiency can be expected.

Note that an optical fiber or a grating may be used as the optical coupling section.

Alternatively, the light modulation section may be an electro-optic effect device in which a comb-shaped electrode 10 is formed in the region of the optical waveguide 2 through which the laser beam 1 passes, as shown in FIG.

Furthermore, the lens that collects the output light of the light modulation section and makes it enter the guiding waveguide may be a geodesic lens 11 having a concave as shown in FIG. 3, or a Fresnel lens as shown in FIG. It may be the lens 12.

(Effects of the Invention) As explained above, according to the present invention, it is possible to realize an optical harmonic generation device which can easily input Raded light and obtain stable harmonic output light, and which can be used to improve the efficiency of laser light in various devices. It is suitable as a wavelength conversion device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a specific example of an optical modulation section, and FIGS. 3 and 4 are specific examples of an optical waveguide lens. 1... Substrate (LiNbOx) 2.3... Optical waveguide 4... Optical coupling part (prism) 5... Laser light 6, 10... Comb-shaped electrode 7
...Surface acoustic wave 8...High frequency power supply 9.11.
12... Optical waveguide lens patent applicant Roku Konishi Photo Industry Co., Ltd. Representative Patent attorney Fuji Ijima 1 person outside the womb Figure 1 Figure 2

Claims (1)

[Claims] Optical harmonics, characterized in that at least a waveguide type optical harmonic generation section and an optical coupling section for inputting laser light into the waveguide type optical harmonic generation section are integrated on a common substrate. Generator.