JPS63279231A - Optical wavelength converting element - Google Patents

Abstract

PURPOSE:To obtain an element which has high conversion efficiency and allows easy mounting and dismounting by providing a light guide to a substrate consisting of a beta-BaB2O4 single crystal, projecting a basic wave to one end face thereof and taking out the converted second harmonic wave. CONSTITUTION:A photoresist is coated on the Z cut face of the beta-BaB2O4 single crystal substrate 1 and a window is opened in the resist. An Al film is then deposited by evaporation thereon and the Al is diffused after lifting off to form the Al-diffused light guide 2. The 2nd harmonic wave 6 subjected to a wavelength conversion is generated in the substrate and can be taken out of the exit end face when the basic wave 5 is cast through a condenser lens 4 from a laser light source 3 to the end face of this guide 2. The converting element can be formed in such a manner. Coupling of optical fibers for incidence and guiding to the element in the stage of forming the element is also possible. The element which has the high conversion efficiency and allows easy handling is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical wavelength conversion element used in the field of laser processing using laser light or the field of application of photochemical energy.

[Prior Art] Conventionally, in a short wavelength region of 0.7 mm or less, it is difficult to oscillate a semiconductor laser, so a large laser such as a gas laser has been used, and an increase in size has been inevitable. Therefore, 5HG (Second Harmonic
An element that converts semiconductor laser light into half the wavelength by utilizing the generation phenomenon (second harmonic) has been fabricated. Examples of substrates for this element include ADP, KDP, and LiN.
Optical wavelength conversion elements have been created using bO3 and the like.

[Problem to be solved in Issue 1] The conventionally used ADP and KDP have a narrow transparent wavelength range (the former has a wavelength range of 0.19 to 1.5 cm, and the latter has a wavelength range of 0.2 cm).
~1.55 pm), has deliquescent properties, and the second-order nonlinear optical constant is not large (the former is d = 0.499 xlo
-”MKS, the latter is d-0,43x 10-”MKS)
LiNb0i'c has a high lower limit of the transparent wavelength range (0,4 to 1) and a small photodestruction threshold (0,4 to 1).
01GW/cm2. There were problems such as λ-1,061Lm).

Therefore, with the former two methods, a very high conversion efficiency cannot be obtained, and with the latter method, harmonics in the ultraviolet region cannot be obtained and the method cannot be used at high input power.

The present invention provides an optical wavelength conversion element that solves the above problems.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and involves injecting a fundamental wave into one end surface of an optical waveguide formed on a single crystal substrate to produce a nonlinear optical effect. In the optical wavelength conversion element that extracts the second harmonic generated originally, β-BaB2O
The present invention provides an optical wavelength conversion element characterized by using a single crystal.

In the present invention, one end surface of a β-Bai2O4 substrate is coated with a photoresist, and then one
/A window is opened in the cyst, a metal thin film is deposited, and after lift-off, the metal is diffused by high-temperature heat treatment in an inert gas and a guide wave path is formed, thereby creating an optical wavelength conversion element.

Moreover, β-BaB2O. The output end face of the optical fiber that has guided the fundamental wave is coupled to the fundamental wave input end face of an optical wavelength conversion element which has a leading wave path with a width and depth of several ILI formed by ion diffusion etc. on one end face of a single crystal. Furthermore, the second harmonic wave converted and generated by the waveguide can be led out by coupling the converted wave output portion of the end face of the optical wavelength conversion element and the input end face of the output waveguide optical fiber.

[Example] Photoresist was applied 2.
According to the 0-order photolithography technique of carefully spin-coding, a window is made in the leading waveguide part, and unnecessary parts are removed from the AI film by a 400-person steam lift-off method, and then the temperature is lowered in an Ar gas atmosphere. Heat treatment is performed at 1000° C. for 6 hours to diffuse A1. Thereafter, in order to compensate for oxygen deficiencies, thermal diffusion was performed for 1 hour while flowing 02 gas. FIG. 1 is a perspective view showing the configuration of this example, in which β-BaB, 0. On the Z-plane of the substrate l, the width is 4pm.
, an A1 diffused optical waveguide 2 having a depth of 2#L■ is formed. The refractive index aperture of the optical waveguide 2 must be larger than that of the substrate l. When the fundamental wave 5 from the laser light source 3 is applied to one end surface of the optical waveguide created in this way through the condensing lens 4, a wavelength-converted second harmonic wave 6 is generated in the substrate 1.
occurs.

This example is the same as the previous example except that an In vapor deposited film is used. I
n is 300. The optical waveguide is formed as in the previous example, but the heat treatment is carried out at 800° C. for 7 hours, with a width of 0, 3 final layers, and a depth of 1 pot.

2 and 3 show embodiments of the present invention, and are perspective views of an optical wavelength conversion element according to the present invention. This will be explained based on the embodiment shown in FIG.

A groove 10 for the optical wavelength conversion element is made on the substrate 8 made of porous glass or the like so that the optical wavelength conversion element 15 can be placed thereon, and grooves 9 and 10 for installing the optical fiber are formed by photolithography so that the optical fiber 1''l and 12 can be installed. Create 8°.

The depth of the groove 10 for the optical wavelength conversion element is adjusted so that the core of the end surface 7' of the optical waveguide 7 and the end surface 11' of the optical fiber coincide.

Of course, the other end of the leading waveguide and the core of the 12° end face of the output side optical fiber must also match.

FIG. 3 shows a third embodiment, in which condensing lenses 13 and 14 are provided at the ends of the input polarizing fiber 11 and the output optical fiber 12 to focus the laser beam. Board 8
etc. are the same as in the previous embodiment.

〔Effect of the invention〕

β-BaB2Os has a short wavelength limit of 190 in the transparent wavelength region.
It is possible to use ultraviolet laser light with an incident fundamental wave of 380 nm, and unlike ADP and KDP, it does not exhibit deliquescent properties, and the effective second-order nonlinear optical constant is d36 of KDP.
This is four times as large as the value of , and an element with high conversion efficiency can be obtained. In addition, the photodestruction threshold is 2MW/ca2 (λ-4,0
It is large (8 μm) and can be used with higher input power than LiNbO3 elements.

In addition, since the fundamental wave input and second harmonic waveguide optical fibers can already be coupled to the input and output parts of the optical wavelength conversion element at the stage of producing the optical wavelength conversion element, at the stage of using the optical wavelength conversion element, , positioning of the incident wave and the output wave path is no longer necessary, the effort for that is saved, and the element can be easily attached and removed. Furthermore, since flexible optical fibers are used, the installation location of the device can be freely selected.

[Brief explanation of drawings]

1 to 3 are perspective views showing the structure of the optical wavelength conversion element according to the present invention. 1-... β-BaBJ<single crystal substrate, 2.7-... Optical waveguide, 3... Laser light source, 4... Condensing lens, 5
...Incoming fundamental wave, 6...Outgoing second harmonic, 7°...
- End face of optical waveguide, 8... Substrate, 9,9°... Groove for installing optical fiber, 10-... Groove for optical wavelength conversion element, 11.12... Optical fiber, 11', 12 '...
・End face of optical fiber, 13:14...Lens for condensing light. difference

Claims (1)

[Claims] β-BaB_2O_
4. An optical wavelength conversion element characterized by using a single crystal.