A wavelength conversion optical element using a nonlinear optical effect of a device structure in which wavelength conversion efficiency rises as targeted when the length of a waveguide is increased is provided. The element adopts a waveguide structure using lithium niobate of a second-order nonlinear optical material. Wavelength conversion regions are formed to correspond to two linear waveguides extending in parallel to each other on a plane of the planar structure and correspond to the lengths of the two linear waveguides. One end side of the linear waveguide is an incident side of excitation light and one end side of the linear waveguide is an emission side of wavelength converted light. The linear waveguides excluding the incident side and the emission side are joined by a bent waveguide. Second-order nonlinear optical media forming the linear waveguides have polarization inversion structures in which directions of spontaneous polarization are periodically inverted with respect to a propagation direction of light.

An optical signal processing device includes: a light source which generates a fundamental wave light; an optical modulator which modulates the fundamental wave light, and generates a fundamental wave light having a plurality of carriers synchronized in phase; an optical filter which passes through required components among the plurality of carriers; a first second-order nonlinear optical element on which a light which passes through the optical filter is incident, and which generates a second harmonic of the fundamental wave light; and a second second-order nonlinear optical element on which a signal light and the second harmonic are incident, the second second-order nonlinear optical element performing nondegenerate parametric amplification, wherein the second second-order nonlinear optical element has an output unit for picking up a wavelength converted light corresponding to difference in frequency between the signal light and the second harmonic or an amplified light of the signal light.

An optical signal processing device includes: a light source which generates a fundamental wave light; an optical modulator which modulates the fundamental wave light, and generates a fundamental wave light having a plurality of carriers synchronized in phase; an optical filter which passes through required components among the plurality of carriers; a first second-order nonlinear optical element on which a light which passes through the optical filter is incident, and which generates a second harmonic of the fundamental wave light; and a second second-order nonlinear optical element on which a signal light and the second harmonic are incident, the second second-order nonlinear optical element performing nondegenerate parametric amplification, wherein the second second-order nonlinear optical element has an output unit for picking up a wavelength converted light corresponding to difference in frequency between the signal light and the second harmonic or an amplified light of the signal light.

A wavelength conversion apparatus using a nonlinear optical medium having a periodically poled structure is operated at an optimal temperature in a stable manner. The wavelength conversion apparatus includes a wavelength converter using a nonlinear optical medium and a controller for controlling temperature of the wavelength converter. The wavelength conversion apparatus further includes a first optical branch coupler for branching part of output light from the wavelength converter, and first and second wavelength separation filters for separating and outputting, from part of the output light, each of two light components generated by parametric fluorescence in the wavelength converter. The controller controls the temperature of the wavelength converter on the basis of difference in light intensity of the two light components.

An optical waveguide structure comprises a nonlinear optical waveguide, straight segments in the nonlinear optical waveguide, and curved segments in the nonlinear optical waveguide. The nonlinear optical waveguide comprises a nonlinear optical material having a second order nonlinear coefficient for a nonlinear optical process in which the second order nonlinear coefficient changes with a direction of light propagation. The straight segments in the nonlinear optical waveguide are oriented such a nonlinear optical interaction with light generation that occurs with an overall constructive manner within the nonlinear optical waveguide in response to a light traveling though the nonlinear optical waveguide. The curved segments have a 90 degree bend, wherein the curved segments connect the straight segments to each other within in the nonlinear optical waveguide.

An optical waveguide structure comprises a nonlinear optical waveguide, straight segments in the nonlinear optical waveguide, and curved segments in the nonlinear optical waveguide. The nonlinear optical waveguide comprises a nonlinear optical material having a second order nonlinear coefficient for a nonlinear optical process in which the second order nonlinear coefficient changes with a direction of light propagation. The straight segments in the nonlinear optical waveguide are oriented such a nonlinear optical interaction with light generation that occurs with an overall constructive manner within the nonlinear optical waveguide in response to a light traveling though the nonlinear optical waveguide. The curved segments have a 90 degree bend, wherein the curved segments connect the straight segments to each other within in the nonlinear optical waveguide.

The invention is related to a parametric light generation method and its application and belongs to the technical field of laser and nonlinear optics. The generation method comprises steps as follows: a nonlinear optical material that meets the sum-frequency phase-matched conditions, namely it shall satisfy the energy conservation condition ω.sub.p+ω.sub.i=ω.sub.s and the momentum conservation condition n.sub.pω.sub.p+n.sub.iω.sub.i=n.sub.sω.sub.s simultaneously, is provided; laser light with a wavelength of λ.sub.p is injected into the said nonlinear optical material as pump light; then, the material will output signal light with a wavelength of λ.sub.s, namely the tunable sum-frequency parametric light. With sum-frequency as the basic principle, the invention can realize frequency up-conversion and obtain visible and UV light sources through simple infrared light sources easily.

A configuration of an excitation light generation device for providing an excitation light having a good SN ratio to a PSA is disclosed. Further, a configuration of a relay amplifier of the PSA including the excitation light generation device is also shown. The following disclosure includes the excitation light generation device, an optical amplification device including the excitation light generation device, and an optical transmission system. More specifically, the excitation light generation device for maintaining the SN ratio of the excitation light in a high state by utilizing an optical sensitive amplification function with respect to the excitation light generated by an optical phase lock loop is disclosed. The excitation light generation device of the present disclosure generates a local oscillation excitation light using the OPLL and having a sufficiently high SN ratio, which makes an inherent low noise operation of the PSA possible even to a signal light having a high SN ratio.

An apparatus includes a substrate transmissive of electromagnetic energy of at least a plurality of wavelengths, having a first end, a second end, a first major face, a second major face, at least one edge, a length, a width, and a thickness, at least a first output optic that outputs electromagnetic energy the substrate; and a first input optic oriented and positioned to provide electromagnetic energy into the substrate via at least one of the first or the second major face of the substrate. The first output optic is laterally spaced from the first input optic. A number of reflectors and optional absorbers may be positioned proximate the first major face and/or the second major face to structure electromagnetic energy and/or to translate such from the first input optic to the first output optic. The apparatus may be part of a spectrometer or other optical system.

An apparatus includes a substrate transmissive of electromagnetic energy of at least a plurality of wavelengths, having a first end, a second end, a first major face, a second major face, at least one edge, a length, a width, and a thickness, at least a first output optic that outputs electromagnetic energy the substrate; and a first input optic oriented and positioned to provide electromagnetic energy into the substrate via at least one of the first or the second major face of the substrate. The first output optic is laterally spaced from the first input optic. A number of reflectors and optional absorbers may be positioned proximate the first major face and/or the second major face to structure electromagnetic energy and/or to translate such from the first input optic to the first output optic. The apparatus may be part of a spectrometer or other optical system.