Optical wavelength converter device and method of manufacturing same

DETAILED DESCRIPTION In view of the aforesaid problems of the conventional optical wavelength converter device, it is an object of the present invention to provide an optical wavelength converter device in the form of a three-dimensional optical waveguide, which can easily be manufactured and can produce a wavelength-converted wave that can be converged sufficiently down to the diffraction limit, and a method of manufacturing such an optical wavelength converter device.
According to the present invention, since semiconductor materials of the III - V and II - VI groups exhibit a high nonlinear optical effect, a cladding and a waveguide element are made of these materials.
More specifically, an optical wavelength converter device is in the form of a three-dimensional optical waveguide and comprises a cladding having a first refractive index and a waveguide element embedded in the cladding and having a second refractive index higher than the first refractive index, each of the cladding and the waveguide element being made of a III - V group, mixed-crystal compound semiconductor material or a II - VI group, mixed-crystal compound semiconductor material, with the cladding covering all surfaces of the waveguide element which fully reflect the fundamental wave.
The optical wavelength converter device according to the present invention is manufactured as follows: A double-heterostructure is deposited on a substrate, the double-heterostructure having an upper layer, a central layer, and a lower layer, each of the upper,.
central, and lower layers being made of a III - V group, mixed-crystal compound semiconductor material or a II - VI group, mixed-crystal compound semiconductor material, and the central layer having a refractive index higher than the refractive index of the upper and lower layers.
Then, opposite ends of the double-heterostructure are removed, thereby producing a mesa on the substrate.
Finally, a homogeneous crystal of a III - V group, mixed-crystal compound semiconductor material or a II - VI group, mixed-crystal compound semiconductor material is grown on the substrate in contact with opposite ends of the mesa, so that the central layer is embedded as a waveguide element in a cladding which is composed of the homogeneous crystal and the upper and lower layers