A wavelength conversion device includes a second-order nonlinear optical medium with a polarization inversion structure, wherein the wavelength conversion device performs wavelength conversion between three wavelengths according to a relationship of 1/λ.sub.1=1/λ.sub.2+1/λ.sub.3, a polarization inversion period Λ of the polarization inversion structure is divided into 2a regions, and when the 2a regions divided from the polarization inversion period Λ each has a width ratio of an inverted region and a non-inverted region of r to 1−r (where 0≤r≤1), a ratio value r is set such that, when one period in phase of a sine function from 0 to 2π is divided into 2a regions, a value of the sine function in a center of each divided region is (1−2r)±0.1.

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.

A system for generating a coherent laser light includes a light source configured to pump a first color laser light and a device configured to generate a coherent second color light and a coherent third color light. The device includes a waveguide configured to couple to the light source and a microring resonator coupled to the light source via the waveguide. The microring resonator is configured to generate a coherent second color light and a coherent third color light. The generation of the coherent second color light and the coherent third color light is based on hybrid-mode optical parametric oscillation.

A miniaturized PPKTP crystal-based entanglement source system using multi-mode reception is provided, which includes a pump light source, a pump light transmission module, an entanglement device, a first collection device, and a second collection device. In the entanglement source system, entangled lights are received by using multi-mode optical fibers, and an entangled light processing scheme of combining a temporal filtering technology and a spatial filtering technology is applied into a collecting device at one side of the entanglement source system, to form asymmetric device structures in the entanglement source system, to enable multi-mode reception.

An exemplary system can be provided which can include, for example, a plurality of source arrangements configured to provide a plurality of electro-magnetic radiations to at least one of at least one sample or at least one reference structure, a first arrangement configured to receive a first radiation(s) from the reference structure(s), a second arrangement configured to receive a second radiation(s) from the sample(s), where a portion(s) of the second radiation(s) can be in an invisible spectrum, a third arrangement configured to combine the first radiation(s) and the second radiation(s) into a third radiation(s), and a fourth arrangement configured to convert the third radiation(s) into a further radiation in a visible spectrum based on the at least one portion.

A solid-state laser system according to an aspect of the present disclosure includes a first non-linear crystal that generates first wavelength-converted light based on a first laser beam, a first adjustment unit configured to perform phase matching of the first wavelength-converted light in the first non-linear crystal, a second non-linear crystal that generates second wavelength-converted light based on a second laser beam and the first wavelength-converted light, a second adjustment unit configured to perform phase matching of the second wavelength-converted light in the second non-linear crystal, a light detection unit configured to detect light having a selected wavelength, and a processor configured to control the first adjustment unit based on intensity of at least one of the first wavelength-converted light and the first laser beam and to control the second adjustment unit based on intensity of at least one of the second wavelength-converted light and the first wavelength-converted light.

An optical-frequency shift device to shift a first optical-signal of a first optical-frequency to a second optical-signal of a second optical-frequency, including a splitter to split the first optical-signal to optical-signals of first and second polarizations, orthogonal each other, a generator to generate first and fourth controlled-light of the first polarization, and second and third controlled-light of the second polarization, each of frequency differences between the first and second controlled-light and between the third and fourth controlled-light having a spacing equal to a difference between the first and second optical-frequencies, a nonlinear optical-medium in which idler light of the second and first polarization are created by causing cross phase modulation of the optical-signals of the first and second polarizations, the first and third controlled-light, and the second and fourth controlled-light, respectively, and an optical-combiner to combine the idler light of the second and first polarization.

A method and apparatus to generate harmonically related laser wavelengths includes a pair of lenses at opposing faces of a non-linear optical material. The lenses are configured to promote incoming and outgoing beams to be normal to each outer lens surface over a range of acceptance angles of the incoming laser beam. This reduces reflection loss for higher efficiency operation. Additionally, the lenses allow a wider range of wavelengths for lasers for more universal application. Examples of the lenses include plano-cylindrical and plano-spherical form factors.

An optical amplifier arrangement has optical parametric amplifiers and white light generations and harmonic generation, in particular frequency doubling, for generating a wide visible to infrared, in any case near-infrared, spectrum of coherent ultra-short light pulses, in particular with a pump laser, and also to a . A method During operation the fundamental is in a wavelength range above 950 nm, and the second signal light and the second idler light of the second optical parametric amplifier together cover a tunability range of wavelengths between 500 nm and 5 μm, in particular between 550 nm and 3 μm, wherein between wavelengths in the tunability range throughout continuous tuning can be carried out, namely through the degeneration range of the second optical parametric amplifier (OPA2) at the fundamental of the pump laser.

The present disclosure provides a liquid crystal phase shifter, comprising a first substrate and a second substrate which are oppositely arranged, and a liquid crystal layer positioned between the first substrate and the second substrate, wherein a plurality of spacers are distributed in the liquid crystal layer, the spacers are in contact with the first substrate and the second substrate, and include a first spacer arranged on the first substrate and a second spacer arranged on the second substrate, and the first spacer and the second spacer are abutted. The present disclosure also provides a manufacturing method of the liquid crystal phase shifter.