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 squeezed light generator (SLG) for generating squeezed light (SQL) is disclosed, said squeezed light generator (SLG) comprising: —a waveguide (WG) being arranged to receive fundamental wavelength laser light (FWL), the waveguide (WG) comprising a second harmonic generator (SHG) for generating second harmonic light (SHL) from the fundamental wavelength light (FWL), —an optical cavity (OC) resonant for both fundamental wavelength light (FWL) and the second harmonic light (SHL), the optical cavity (OC) being arranged to receive the second harmonic light (SHL), and —a parametric down converter (PDC) arranged inside said optical cavity (OC), the parametric down converter (PDC) being adapted for generating said squeezed light (SQL) using said second harmonic light (SHL). Also, a method for generating squeezed light (SQL) is disclosed.

A nonlinear fiber interferometer is disclosed suitable for fiber sensor and other applications. A first nonlinear fiber section amplifies probe and conjugate sidebands of a pump through four-wave mixing. A second section introduces a phase shift to be measured, for example from a sensor. A third nonlinear fiber section amplifies with phase-sensitive gain to increase signal-to-noise ratio. Based on phase-sensitive output power of probe and/or conjugate components, the phase shift can be measured. Superior performance can be obtained by balancing gain between the (first and third) nonlinear sections. Non-fiber, for example photonic integrated circuit, embodiments are disclosed. Differential sensing, alternative detection schemes, sensing applications, associated methods, and other variations are disclosed.

In some embodiments, a device for generating mid-infrared radiation is provided. The device may include a thin film quadratic nonlinear waveguide formed on a mid-infrared transparent cladding by a thin film material of a predetermined film thickness, the waveguide having a predetermined etch depth and a predetermined top width. At least one of the predetermined film thickness, the predetermined etch depth, and the predetermined top width may be tuned for the device to generate a coherent idler wave as a mid-infrared radiation from a fixed pump wave and a tunable signal wave.

A self-seeded optical parametric amplifier (OPA) system includes a cavity mirror, a wavelength conversion unit, and a dichroic filter. The cavity mirror is configured to allow high transmission for an input laser beam and high reflection for a feedback beam. The wavelength conversion unit is configured to convert the input laser beam into a signal laser beam and an idler laser beam. The dichroic filter is configured to allow one of the signal laser beam and the idler laser beam to pass through the dichroic filter and reflect the other one onto a feedback path.

The invention is a nonlinear Raman optical device generating zig-zag radiation beam paths in a nonlinear medium having dichroic coatings reflecting at a pump radiation wavelength, with a first mirror between an injected beam of pump radiation and a first end of the nonlinear medium and a second mirror at a second end of the nonlinear medium, the second mirror being partially reflecting at a first Stokes wavelength of the pump radiation.

A method, apparatus, and system for non-linear optical process. A first light of a first wavelength is routed in a first loop in a main nonlinear optical waveguide. The first loop has a first length for the first light of the first wavelength. A second light of a second wavelength is routed in a second loop that includes portions of the main nonlinear optical waveguide and a first extension optical waveguide. The second loop has a second length for the second light of the second wavelength. A third light of a third wavelength is routed in a third loop that include portions of the main nonlinear optical waveguide and a second extension optical waveguide. The third loop has a third length for the third light of the third wavelength.

An optical waveguide structure comprises a first coupler and a second coupler that, in combination, direct a first-wavelength light to travel through a nonlinear-optical waveguide, the two couplers and an extension waveguide but not a secondary waveguide, a first resonator loop is defined for which the first-wavelength light is resonant. The two couplers, in combination, also direct a second-wavelength light to travel through the nonlinear-optical waveguide, the two couplers and the secondary waveguide but not the extension waveguide, wherein a different second resonator loop is defined for which the second-wavelength light is resonant.

An optical waveguide structure comprises a nonlinear optical waveguide comprising a nonlinear optical material having a second order nonlinear coefficient that changes with a direction of light propagation. A first portion of the nonlinear optical waveguide in which a light propagating through the first portion is affected by a positive value of a second order nonlinear coefficient. A second portion of the nonlinear optical waveguide in which the light propagating through the first portion is affected by a negative value of a second order nonlinear coefficient, wherein a set of dimensions in the nonlinear optical waveguide in the first portion and the second portion is selected to cause the light to have a phase walk-off that is an odd multiple of 180 degrees.

Improved efficiency for nonlinear optical interactions is provided by using strongly confining waveguides for simultaneous imposition of dispersion design constraints at two or more dispersion orders. Quasi-phase-matching allows for phase-matching to be accomplished independently of the waveguide design, which helps provide sufficient design freedom for the dispersion design.