Wavelength conversion element

Claim 2

A wavelength conversion element comprising: a substrate made of LiTaO 3 , LiNbO 3 or LiNbO 3 doped with MgO of non-linear optical medium; a plurality of three-dimensional waveguides formed in the substrate and crossed on the substrate; a potential difference application means formed on an intersection to apply a potential difference for change of optical path of a fundamental wave guided through a waveguide; and a second harmonic generation means formed on at least one of the plurality of waveguides for defining a change in refractive index in a waveguide with a period Λ and generating a second harmonic of the fundamental wave introduced into the waveguide, where Λ=2mπ/{β(2ω)-2β(ω)}, where m is a natural number, ω is a frequency of the fundamental wave, β(ω) is a propagation constant of the fundamental wave, and β(2ω) is a propagation constant of the second harmonic.

Claim 3

A wavelength conversion element according to claim 1, wherein a polarization with a direction of an electric field parallel to a x axis is used as the fundamental wave and a polarization with a direction of an electric field parallel to the x axis is used as the second harmonic in a case where a ±c plate is used as the substrate, a direction of light propagation is taken as a z axis and the x axis perpendicular to the z axis is taken as a ±c axis of the substrate.

Claim 4

A wavelength conversion element according to claim 1, wherein a y-directional polarization with a direction of an electric field parallel to a y axis is used as the fundamental wave and a polarization with a direction of an electric field parallel to an x axis is used as the second harmonic in a case where a ±c plate is used as the substrate, a direction of light propagation is taken as a z axis and a ±c axis of the substrate is taken as the x axis perpendicular to the z axis.

Claim 5

A wavelength conversion element according to claim 1, wherein the second harmonic generation means comprises polarization inversion layers transverse of the waveguide and arranged with the period Λ for each other.

Claim 6

A wavelength conversion element according to claim 1, wherein the second harmonic generation means comprises polarization inversion layers arranged with the period Λ for each other on both sides of the waveguide.

Claim 7

A wavelength conversion element according to either one of claims 4 or 5, wherein the polarization inversion layers are formed by proton exchange of the substrate.

Claim 8

A wavelength conversion element comprising: a substrate of non-linear optical medium; a plurality of three-dimensional waveguides formed in the substrate and crossed on the substrate; a potential difference application means formed on an intersection to apply a potential difference for change of optical path of a fundamental wave guided through a waveguide; and a shorter wavelength harmonic generation means formed on at least one of the plurality of waveguides for generating a shorter wavelength harmonic from the fundamental wave introduced into the waveguide.

Claim 9

A wavelength conversion element comprising: a substrate of non-linear optical medium; a plurality of three-dimensional waveguides formed in the substrate and crossed on the substrate; a potential difference application means formed on an intersection to apply a potential difference for change of optical path of a fundamental wave guided through a waveguide; and a shorter wavelength harmonic generation means formed on at least one of the plurality of waveguides for generating a shorter wavelength harmonic from the fundamental wave introduced into the waveguide.

Claim 10

A wavelength conversion element according to claim 7, wherein said wavelength conversion element further comprises a shorter wavelength harmonic annihilation means for annihilating the generated shorter wavelength harmonic.

Claim 11

A wavelength conversion element according to claim 7, wherein the substrate is formed of non-linear optical medium of LiTaO 3 .

Claim 12

A wavelength conversion element according to claim 7, wherein the shorter wavelength harmonic generation means is constructed by a phase matching portion for matching phases of the fundamental wave and the shorter wavelength harmonic generated therefrom.

Claim 13

A wavelength conversion element according to claim 7, wherein the substrate is made of non-linear optical medium of LiNbO 3 or LiNbO 3 doped with MgO.

Claim 14

A wavelength conversion element according to claim 10, wherein the phase matching portion is formed by polarization inversion with a predetermined period, or by birefringence of non-linear optical medium.

Claim 15

A wavelength conversion element according to either one of claims 9 or 11, wherein the plurality of waveguides are proton exchange waveguides.

Claim 16

A wavelength conversion element according to claim 8, wherein the shorter wavelength harmonic annihilation means is constructed by a cladding metal layer to absorb the shorter wavelength harmonic.

Claim 17

A wavelength conversion element comprising: a substrate made of LiTaO 3 , LiNbO 3 or LiNbO 3 doped with MgO of non-linear medium; a three-dimensional waveguide formed in the substrate; and a second harmonic generation means for defining a change in refractive index in the waveguide with a period Λ and generating a second harmonic of a fundamental wave introduced into the waveguide, where Λ=2mπ/{β(2ω)-2β(ω)}, where m is a natural number, ω is a frequency of the fundamental wave, β(ω) is a propagation constant of the fundamental wave, and β(2ω) is a propagation constant of the second harmonic, wherein a y-directional polarization with a direction of an electric field parallel to a y axis is used as the fundamental wave and a polarization with a direction of an electric field parallel to an x axis is used as the second harmonic in a case where a ±c plate is used as the substrate, a direction of light propagation is taken as a z axis and a ±c axis of the substrate is taken as the x axis perpendicular to the z axis.

Claim 18

A wavelength conversion element comprising: a substrate made of LiTaO 3 , LiNbO 3 or LiNbO 3 doped with MgO of non-linear medium; a three-dimensional waveguide formed in the substrate; and a second harmonic generation means for defining a change in refractive index in the waveguide with a period Λ and generating a second harmonic of a fundamental wave introduced into the waveguide, where Λ=2mπ/{β(2ω)-2β(ω)}, where m is a natural number, ω is a frequency of the fundamental wave, β(ω) is a propagation constant of the fundamental wave, and β(2ω) is a propagation constant of the second harmonic, wherein a y-directional polarization with a direction of an electric field parallel to a y axis is used as the fundamental wave and a polarization with a direction of an electric field parallel to an x axis is used as the second harmonic in a case where a ±c plate is used as the substrate, a direction of light propagation is taken as a z axis and a ±c axis of the substrate is taken as the x axis perpendicular to the z axis.

Claim 19

A wavelength conversion element according to claim 15, wherein the second harmonic generation means comprises polarization inversion layers transverse of the waveguide and arranged with the period Λ for each other.

Claim 20

A wavelength conversion element according to claim 15, wherein the second harmonic generation means comprises polarization inversion layers arranged with the period Λ for each other on both sides of the waveguide.