A system for nonlinear frequency conversion includes an acousto-optic modulator for diffracting a portion of an input laser beam as a first-order beam and transmitting a non-diffracted portion of the input laser beam as a zeroth-order beam. The system also includes a nonlinear crystal arranged to receive and frequency convert each of the zeroth-order and first-order beams to generate two respective frequency-converted laser beams, whereby, when the acousto-optic modulator changes the average-power ratio between the zeroth-order and first-order beams, variations of the heat load in the nonlinear crystal are minimized. Either one of the two frequency-converted laser beams may be used as an output laser beam of the system, while the other one of the two frequency-converted laser beams serves to stabilize the heat load in the nonlinear crystal when the acousto-optic modulator is operated to change the average power in the output laser beam.

A light generation and light distribution method. The method includes generating laser light with a semiconductor laser or an array of semiconductor lasers at a generation location. Light generated by the semiconductor laser is guided to a frequency converter. Light converted by the frequency converter is directed to a plurality of distribution locations. The distribution locations can be remote or local. A light generation and light distribution system includes a semiconductor laser or array of lasers at a generation location. A frequency-conversion optical component modifies the wavelength of the radiation generated by the semiconductor laser to one or more desired wavelengths for disinfection, medical therapy, photochemical processes, and/or lighting. Light extraction and distribution optical components extract from the distribution system a portion of the light in the system so as to provide for one or more of disinfection, medical therapies, general or background lighting, and photochemical processes.

A light generation and light distribution method. The method includes generating laser light with a semiconductor laser or an array of semiconductor lasers at a generation location. Light generated by the semiconductor laser is guided to a frequency converter. Light converted by the frequency converter is directed to a plurality of distribution locations. The distribution locations can be remote or local. A light generation and light distribution system includes a semiconductor laser or array of lasers at a generation location. A frequency-conversion optical component modifies the wavelength of the radiation generated by the semiconductor laser to one or more desired wavelengths for disinfection, medical therapy, photochemical processes, and/or lighting. Light extraction and distribution optical components extract from the distribution system a portion of the light in the system so as to provide for one or more of disinfection, medical therapies, general or background lighting, and photochemical processes.

The present invention provides a system for detecting whether a subject having a target suffers from an Alzheimer's disease. The system includes a multi-harmonic generation microscope and a processor. The multi-harmonic generation microscope images the target by a second harmonic generation (SHG) and a third harmonic generation (THG) to respectively obtain an SHG image and a THG image. The processor couples to the multi-harmonic generation microscope and configures to add a first color to the SHG image and a second color to the THG image to respectively obtain a color-added SHG image and a color-added THG image, and combine the color-added SHG image and the color-added THG image to obtain a combined image, wherein the combined image is used to determine whether the subject suffers from the Alzheimer's disease.

The present invention provides a system for detecting whether a subject having a target suffers from an Alzheimer's disease. The system includes a multi-harmonic generation microscope and a processor. The multi-harmonic generation microscope images the target by a second harmonic generation (SHG) and a third harmonic generation (THG) to respectively obtain an SHG image and a THG image. The processor couples to the multi-harmonic generation microscope and configures to add a first color to the SHG image and a second color to the THG image to respectively obtain a color-added SHG image and a color-added THG image, and combine the color-added SHG image and the color-added THG image to obtain a combined image, wherein the combined image is used to determine whether the subject suffers from the Alzheimer's disease.

An all-optical optical parametric oscillator includes a laser module, a temperature control module, a plurality of filters and a beam splitter arranged in sequence. A bulk material or waveguide material is arranged in the temperature control module. Both ends of the bulk material are provided with a first OPO cavity mirror M.sub.1′ and a second OPO cavity mirror M.sub.2′. Each of the first OPO cavity mirror M.sub.1′ and the second OPO cavity mirror M.sub.2′ is coated with a high-reflectivity film with respect to an OPO signal light and an OPO idler light, and coated with a high-transmittance film with respect to an OPO pump light, a poling fundamental frequency light and a poling frequency doubled light. The temperature of the material is changed by changing the temperature of the temperature control module to realize temperature tuning of wavelength λ.sub.s of the OPO signal light and wavelength λ.sub.i of the OPO idler light.

An all-optical optical parametric oscillator includes a laser module, a temperature control module, a plurality of filters and a beam splitter arranged in sequence. A bulk material or waveguide material is arranged in the temperature control module. Both ends of the bulk material are provided with a first OPO cavity mirror M.sub.1′ and a second OPO cavity mirror M.sub.2′. Each of the first OPO cavity mirror M.sub.1′ and the second OPO cavity mirror M.sub.2′ is coated with a high-reflectivity film with respect to an OPO signal light and an OPO idler light, and coated with a high-transmittance film with respect to an OPO pump light, a poling fundamental frequency light and a poling frequency doubled light. The temperature of the material is changed by changing the temperature of the temperature control module to realize temperature tuning of wavelength λ.sub.s of the OPO signal light and wavelength λ.sub.i of the OPO idler light.

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.