A linearly polarized upconverting optical signal at optical frequency ν.sub.OPT and a propagating input signal at frequency ν.sub.GHz are combined by an input beam combiner to copropagate through a nonlinear optical medium and generate upconverted optical signals at one or both sum or difference frequencies ν.sub.SUM=ν.sub.OPT+ν.sub.GHz or ν.sub.DIFF=ν.sub.OPT−ν.sub.GHz. The orthogonally polarized upconverting and upconverted optical signals are separated by a polarizer, and the upconverted optical signal is preferentially transmitted to a detection system by an optical filter. The input signal is modulated to encode transmitted information, and that modulation is imparted onto the upconverted optical signal. The detection system includes one or more photodetectors, receives the upconverted optical signal, and generates therefrom electrical signals that are modulated to encode the transmitted information.

A frequency conversion device, including a source of a pump beam of electromagnetic radiation of a first wavelength, and an array of mutually spaced semiconductor islands including at least one III-V semiconductor compound and configured so that the pump beam of electromagnetic radiation of the first wavelength incident upon the semiconductor islands and electromagnetic radiation of a second wavelength incident upon the semiconductor islands cause the semiconductor islands to emit electromagnetic radiation of a third wavelength different to the first and second wavelengths by at least one of a sum frequency generation process and a difference frequency generation process, wherein the semiconductor islands are supported by a transparent support such that the support is substantially transparent to radiation of the third wavelength, wherein at least the radiation of the third wavelength passes through the transparent support.

One aspect of the present disclosure relates to a medical laser system, comprising: a first laser source comprising at least a first gain medium for generating a first optical field; and at least one first U-switch configured to control a resonance quality of the first laser source; a control circuit configured to control the first U-switch to cause the first laser source to generate the first optical field as a first pulse train of laser pulses; a second laser source for generating a second optical field as a second pulse train of laser pulses; at least one nonlinear medium for generating a third optical field by a nonlinear interaction between the first optical field and the second optical field; a sensor configured to detect a property of at least one of the optical fields; wherein the control circuit is configured to control operation of the first U-switch so as to adjust a relative timing of the laser pulses of the first pulse train and the laser pulses of the second pulse train responsive to the detected property.

An optical quantum state converter comprises an optical fiber input port configured to receive an optical signal comprising an optical quantum state at a first wavelength from an optical source. An optical combiner having a first input is coupled to the optical fiber input port. An optical pump source having an output that is coupled to a second input of the optical combiner provides an optical pump signal at a pump signal wavelength to a second input of the combiner. A nonlinear optical waveguide having an input that is coupled to an output of the optical combiner converts the optical quantum state at the first wavelength to an optical quantum state at a second wavelength determined by the optical pump signal.

A terahertz-wave generation method of generating a terahertz wave in a direction satisfying a non-collinear phase-matching condition by making pump light incident on a nonlinear optical crystal capable of generating a terahertz wave by optical parametric effect, makes the pump light incident on the nonlinear optical crystal so that a peak excited power density is equal to or greater than a predetermined terahertz-wave lasing threshold and equal to or less than a predetermined laser damage threshold, and an average excited power density, is equal to or less than a predetermined photorefractive effect occurrence threshold, the pump light having a pulse width of 10 ps or more, the pulse width of 1 ns or less, and a repetition frequency of 1 kHz or more.

A pressure cell for sum frequency generation spectroscopy includes: a metal pressure chamber; a heating stage that heats the liquid sample; a pump, connected to an interior of the metal pressure chamber, that pressurizes the interior of the metal pressure chamber; and a controller that controls the pump and the heating stage to control a pressure of the interior of the metal pressure chamber and a temperature of a liquid sample. The metal pressure chamber includes: a base that retains the liquid sample; a removable lid that seals against the base to enclose the liquid sample in the metal pressure chamber; and a window in the removable lid that exposes the liquid sample to an exterior of the metal pressure chamber.

An optic produces a beam of ultraviolet laser radiation from a beam of visible laser radiation and spatially separates the ultraviolet laser beam from the visible laser beam. The optic includes two crystals made of the same optically-nonlinear material that are contact bonded along a planar interface. One crystal has principle crystal axes that are oriented for type-I second-harmonic generation. The ultraviolet laser beam exits the optic through an uncoated surface of the other crystal. The principle crystal axes of the two crystals have different orientations and have reflection symmetry about the planar interface.

Optical transmitters and optical receivers utilizing long wave infrared light for use with an earth-orbiting satellite communication system, and a structure including an intracavity optical nonlinear process, are described herein. The transmitters include a pumping laser diode with a fast-axis collimating lens and a pumping wavelength λ0, operating in a continuous wavelength (CW) mode. The transmitters also include a laser cavity having a beam combiner or a dichroic mirror, a laser crystal with a lasing wavelength λ1 and a difference frequency generation orientation patterned semiconductor to generate long wave-IR light. The transmitters also include a second laser at a wavelength λ2, operating in a modulation mode. The receivers have a similar structure to the transmitters, utilizing a sum frequency generation orientation patterned semiconductor to convert long wave-IR light into the short wave-IR.

An optic produces a beam of ultraviolet laser radiation from a beam of visible laser radiation and spatially separates the ultraviolet laser beam from the visible laser beam. The optic includes two crystals made of the same optically-nonlinear material that are contact bonded along a planar interface. One crystal has principle crystal axes that are oriented for type-I second-harmonic generation. The ultraviolet laser beam exits the optic through an uncoated surface of the other crystal. The principle crystal axes of the two crystals have different orientations and have reflection symmetry about the planar interface.

An optical parametric device (OPD), which is selected from an optical parametric oscillator (OPO) or optical parametric generator (OPG), is configured with a nonlinear optical element (NOE) which converts an incoupled pump radiation at first frequency into output signal and idler radiations at one second frequency or different second frequencies, which is/are lower than the first frequency, by utilizing nonlinear interaction via a random quasi-phase matching process (RQPM-NOE). The NOE is made from a nonlinear optical material selected from optical ceramics, polycrystals, micro and nanocrystals, colloids of micro and nanocrystals, and composites of micro and nanocrystals in polymer or glassy matrices. The nonlinear optical material is prepared by modifying a microstructure of the initial sample of the NOE such that an average grain size is of the order of a coherence length of the three-wave interaction which enables the three wave nonlinear interaction with a highest parametric gain achievable via the RQPM process