Optical wavelength conversion device and method for manufacturing the same
An object is to provide, for example, a method for manufacturing an optical wavelength conversion device having a structure that enables efficient formation of crystal regions on the surface of, or inside, an amorphous material. An amorphous main body is intermittently irradiated with a first laser beam for generating a high-density excited electron region inside the main body and a second laser beam for heating the high-density excited electron region, with respective focus regions of the first and second laser beams overlapping each other. During the intermittent irradiation with the first and second laser beams, the relative position of the main body and the overlapping focus region of the first and second laser beams are varied. This enables part of the main body where the overlapping focus region moves to serve as a heat source for forming a crystal region.
1. A method for manufacturing an optical wavelength conversion device, comprising:
a preparing step of preparing a main body made of an amorphous material;
a first irradiating step of irradiating the main body with a first laser beam focused on a surface of or inside the main body and exciting electrons in a focus region of the first laser beam, the first laser beam being a femtosecond laser beam having a wavelength outside an absorption wavelength band of the main body;
a second irradiating step of irradiating the main body with a second laser beam focused to overlap the focus region of the first laser beam and heating the focus region of the first laser beam, the second laser beam being a continuous wave laser beam or a pulsed laser beam with a pulse width of one picosecond or more, the second laser beam being a laser beam having, outside the focus region of the first laser beam, a wavelength outside the absorption wavelength band of the main body; and
a scanning step of varying a relative position of the main body and an overlapping focus region of the first and second laser beams while the first and second irradiating steps are being intermittently carried out in a synchronized manner.
2. The method according to claim 1 , wherein
the main body is made of BaO—TiO 2 —GeO 2 —SiO 2 -based glass or SrO—TiO 2 —SiO 2 -based glass.
3. The method according to claim 2 , wherein
the main body includes a metal of any of the lanthanoid series, actinoid series, and group 4 to group 12 as an additive.
4. The method according to claim 1 , wherein
the first laser beam includes any of a laser beam output from a titanium-sapphire laser, a laser beam obtained by converting a wavelength of the laser beam output from the titanium-sapphire laser, a laser beam output from a ytterbium-doped fiber laser, and a laser beam obtained by converting a wavelength of the laser beam output from the ytterbium-doped fiber laser.
5. The method according to claim 1 , wherein
the second laser beam includes a laser beam output from any of a carbon dioxide laser, an ytterbium-doped fiber laser, and a semiconductor laser.
6. The method according to claim 1 , further comprising
a processing step of forming a channel waveguide structure in the main body before the first and second irradiating steps or after the scanning step, the channel waveguide structure having an optical axis extending along a direction in which the overlapping focus region of the first and second laser beams moves.