JPH01283527A - Light wavelength converting device - Google Patents

Abstract

PURPOSE:To improve the efficiency of the coupling of semiconductor laser light with an optical waveguide by aligning the center of a diffraction grating with the start point of the optical waveguide. CONSTITUTION:The optical waveguide 14 is provided so as to have an opening in the center of the arc of the arcuate diffraction grating 13 formed on the surface of an optical waveguide layer 12. Namely, light which is radiated on the surface of the arcuate diffraction grating optical waveguide layer larger than the beam diameter of the incident laser light is diffracted and coupled with the optical waveguide, and also converged in the optical waveguide layer and made incident on the optical waveguide. Consequently, the efficiency of the coupling is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical wavelength conversion device necessary for utilizing laser light emitted from a semiconductor laser light source in optical memory devices, laser printers, and the like.

Conventional technology Conventionally, second harmonic generation (
It is well known that converting the wavelength of a laser beam into % by using SHG (hereinafter abbreviated as SHG) (Japanese Patent Laid-Open No. 61-7222
Publication No. 2, etc.).

Figures 3 and 4 show conventional optical wavelength conversion devices.
is L 1Nbc)3 single crystal substrate, 2 is L INbC)s
An optical waveguide formed on a single crystal substrate 1; 3 is a light incidence part;
4 is an SHG element (LiNbc) 3 single crystal substrate 1. It is formed from an optical waveguide 2. 5 is a semiconductor laser, 6 is a collimating lens, and 7 is a focus lens. When the light 8 of the semiconductor laser 6 that has been focused by the collimating lens 6 and the focus lens 7 is incident on the light incidence section 3, nonlinear optics in the optical waveguide 2 is generated. The second harmonic (hereinafter abbreviated as SH light) 9 whose wavelength has been converted by the effect is LiNb0. It is generated in the single crystal substrate 1 and taken out to the outside. Note that 10 is the primary light that has passed through the optical waveguide 2.

Problems to be Solved by the Invention However, as shown in FIG. Since the semiconductor laser beam 8 can be focused to a diameter of only about 1 μm, the coupling efficiency introduced into the optical waveguide 3 as shown in FIG. 8 is geometrically expressed as follows. In reality, the focused spot diameter is determined by the light intensity e-2, so the coupling efficiency for the light generated from the semiconductor laser 5 is ○. It will be less than 6.

In an optical waveguide-type optical wavelength conversion element, the SH light intensity can be extracted in proportion to the square of the incident light intensity, so increasing the coupling efficiency to the optical waveguide has been a major problem in terms of frequency loss.

A first aspect of the present invention is to provide an optical wavelength conversion device in which the efficiency of coupling semiconductor laser light to a waveguide is increased in view of the above points.

a nonlinear optical crystal substrate, an optical waveguide layer formed on the nonlinear optical crystal substrate, a diffraction grating formed on the optical guide, and one end of the optical waveguide layer formed on the nonlinear optical crystal substrate. An optical wavelength conversion device comprising an optical waveguide having a starting point at , the center of the diffraction grating coincides with the starting point of the optical waveguide.

Function The function of the present invention is to diffract the light irradiated onto the optical waveguide surface of the arc-shaped diffraction grating, which is larger than the beam diameter of the incident laser beam, and to couple it to the optical waveguide layer, and to condense the light within the optical waveguide u. Furthermore, the coupling efficiency can be increased by making the light incident on an optical waveguide.

Embodiment Hereinafter, an optical wavelength conversion device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a main configuration diagram of an optical wavelength conversion device in an embodiment of the present invention. In the figure, 11 is a nonlinear optical crystal substrate, 12 is an optical waveguide layer formed on the nonlinear optical crystal substrate 11, 13 is an arcuate diffraction grating provided on the optical waveguide @ 12, and 14 is the nonlinear optical crystal substrate 1. An optical waveguide is formed on top of the optical waveguide. The operation of the optical wavelength conversion device configured as described above will be described below with reference to FIGS. 1 and 2.

FIG. 2 is a sectional view of the main part of FIG. 1, and the same parts as those in FIG.

16 is a laser beam emitted from a laser light source (not shown), and 16 is a laser beam that propagates through the waveform layer 12 (hereinafter referred to as propagating light). Now, a laser beam 16 emitted from a laser light source (not shown) is diffracted by an arcuate diffraction grating 13 that is sufficiently larger than its beam width. Of this diffracted light,
The laser light that enters the optical waveguide layer 12 at a specific angle of incidence determined by the thickness of the light L4ffV12 is reflected within the optical waveguide layer 12 and becomes propagated light 16. In addition, since the arc-shaped diffraction grating 13 has a light effect on the diffracted light,
The propagating light 16 is centered around the arc core of the arc-shaped diffraction grating 130, propagates through the optical waveguide 14 having an opening M at the center of the arc, and generates a second harmonic wave.

As described above, the light guide f1. Es14
An arc-shaped diffraction grating 130 formed on the surface of the optical waveguide layer 12
By providing an opening at the center of the arc, most of the laser light incident on the arc-shaped diffraction grating 13 can be made to enter the light guide path 14. Since the arcuate diffraction grating 13 can be made much larger than the aperture size of the optical waveguide 14, there is no need to condense the laser beam and make it incident as in the conventional example.

Although the second harmonic has been described in the embodiment, the third harmonic has been described.
The fourth harmonic can also be extracted using a similar configuration.

Effects of the Invention As described above, the present invention provides a laser light source, a nonlinear optical crystal, an optical waveguide layer formed on a partial area of the surface of the nonlinear optical crystal, and numerous concentric arc-shaped arcs formed on the surface of the optical waveguide layer. In an optical wavelength conversion device comprising a diffraction grating consisting of small grooves and an optical waveguide formed on the surface of the nonlinear optical crystal and having a starting point at one end of the optical waveguide layer, the center of the diffraction grating is located at the center of the optical waveguide. By arranging it so that it coincides with the starting point, the diffracted light of the laser light incident on the arcuate diffraction grating can be made to enter the optical waveguide.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of an optical wavelength conversion device according to an embodiment of the present invention, FIG. 2 is a sectional view of the same, FIG. 3 is a block diagram of a conventional optical wavelength conversion device, and FIG. 4 is a diagram of the same device. FIG. 5 is a perspective view of the main part, and FIG. 5 is a sectional view of the main part of the device. 11...Nonlinear optical crystal substrate, 12...
・Optical waveguide layer, 13... Arc-shaped diffraction grating, 14.
...Optical waveguide. Name of agent: Patent attorney Toshio Nakao and 1 other person11
-・Back Rubo 1st string, j4- Ahead MIF pumping route 2nd figure

Claims (1)

[Claims] a laser light source, a nonlinear optical crystal substrate, an optical waveguide layer formed on the nonlinear optical crystal substrate, a diffraction grating formed on the optical waveguide layer, and an optical waveguide layer formed on the nonlinear optical crystal substrate. and an optical waveguide having a starting point at one end thereof, wherein the center of the diffraction grating coincides with the starting point of the optical waveguide.