Wavelength Converter
Provided is a wavelength converter that receives signal light and generates difference frequency light having a wavelength different from the signal light, the wavelength converter including: an optical waveguide core; a substrate having a refractive index lower than the optical waveguide core with respect to the signal light; a wavelength conversion element that converts the wavelength of the signal light; an overcladding formed on at least a part of a surface of the optical waveguide core and having a refractive index lower than the optical waveguide core with respect to optical wavelengths of the signal light and control light multiplexed with the signal light; and a temperature control element that controls a temperature of the wavelength conversion element.
1 . A wavelength converter that receives signal light and generates light having a wavelength different from a wavelength of the signal light, the wavelength converter comprising:
a wavelength conversion element that includes an optical waveguide core and a substrate having a refractive index lower than the optical waveguide core with respect to the signal light and converts the wavelength of the signal light;
an overcladding layer formed on at least a part of a surface of the optical waveguide core and having a refractive index lower than the optical waveguide core with respect to optical wavelengths of the signal light and control light multiplexed with the signal light; and
a temperature control element that controls a temperature of the wavelength conversion element.
2 . The wavelength converter according to claim 1 , wherein the refractive index of the overcladding layer is in a range of 0% or more and 25% or less lower than the refractive index of the optical waveguide core.
3 . The wavelength converter according to claim 1 , wherein the overcladding layer contains lithium niobate (LiNbO 3 ), potassium niobate (KNbO 3 ), lithium tantalate (LiTaO 3 ), lithium tantalate having a non-stoichiometric composition (LiNb(x)Ta(1−x)O 3 (0≤x≤1)), or potassium phosphate titanate (KTiOPO 4 ), further, zirconium (Zr), magnesium (Mg), zinc (Zn), scandium (Sc), or indium (In), or at least one oxide selected from zirconium (Zr), niobium (Nb), tantalum (Ta), hafnium (Hf), magnesium (Mg), zinc (Zn), scandium (Sc), titanium (Ti), yttrium (Y), aluminum (Al), indium (In), or silicon (Si), or
a polyolefin such as a polyethylene, a polypropylene, or a polybutylene, a polydiene such as a polybutadiene or natural rubber, a vinyl polymer such as a polystyrene, a polyvinyl acetate, a polymethyl vinyl ether, a polyethyl vinyl ether, a polyacrylic acid, a polymethyl acrylate, a polymethacrylic acid, a polymethyl methacrylate, a polybutyl methacrylate, a polyhexyl methacrylate, or a polydodecyl methacrylate, a linear olefin-based polyether, a polyphenylene oxide (PPO), or a copolymer or a blend thereof, a polyethersulfone (PES) in which an ether group and a sulfone group are mixed, a polyetherketone (PEK) in which an ether group and a carbonyl group are mixed, a polyether such as a polyphenylene sulfide (PPS) or a polysulfone (PSO) having a thioether group, or a copolymer or a blend thereof, a polyolefin having at least one substituent such as an OH group, a thiol group, a carbonyl group, or a halogen group at a terminal, an epoxy resin, a crosslinked product by an oligomer and a curing agent, or a mixture obtained by mixing two or more kinds of the above materials.
4 . The wavelength converter according to claim 1 , wherein lithium niobate (LiNbO 3 ) is used for the optical waveguide core and lithium tantalate (LiTaO 3 ) is used for the substrate, and the overcladding layer is provided on the surface of the optical waveguide core, the overcladding layer having the refractive index in a range of 0% or more and 25% or less lower than the optical waveguide core in the optical wavelengths of the signal light and the control light.