Tunable monolithic cavity-based frequency converter pumped by a single-frequency laser where cavity resonance(s) are achieved by independently changing the temperatures of different sections of the crystal, including the periodically poled section and one or more adjacent, non-poled regions. Having independent control of the phase matching temperature and the cavity resonance for a down-converted beam increases the efficiency.

The disclosure herein generally relates to a system (10) for converting an input light (12) into an output light beam (14) that has a spatial beam quality that is greater than that of the input light (12). The system (10) comprises an optical resonator having disposed therein a Raman crystal (20). The Raman crystal (20) is for receiving the input light (12) and the optical resonator is configured to resonate a Stokes light beam (22) generated from the input light (12) by at least one nonlinear interaction within the Raman crystal (20). The at least one nonlinear interaction comprises at least one Raman interaction. The Stokes light beam (22) has a spatial beam quality that is greater than that of the input light (12). The system (10) comprises a light extractor (18) arranged to generate the output light beam (14) by extracting at least some of the Stokes light beam (22) from the optical resonator.

In one aspect, a device for generating triplet photons is disclosed, which includes a waveguide extending from a proximal end for receiving pump radiation to a distal end through which triplet photons generated via nonlinear interaction of the pump radiation with the waveguide exit the waveguide, where the waveguide is configured such that the triplet photons generated within the waveguide reach its distal end at a rate in a range of about 0.05 triplet photons/second/mW and 0.3 triplet photons/second/mW, e.g., in a range of about 0.1 triplet photons/second/mW to about 0.2 triplet photons/second/mW.

Systems and methods for spectrally broadening seed pulses with a single pass laser amplifier are disclosed. A bulk TM:II-VI polycrystalline material with combined gain and nonlinear characteristic provides passive (cold) spectral broadening of high power seed pulses. Continuous pumping provides more significant spectral broadening. In particular, pulsed pumping of TM:II-VI polycrystalline material (e.g. Cr2+:ZnS, Cr2+:ZnSe, and Cr2+:CdSe) is shown to provide significant spectral broadening to the super continuum generation SCG level. Pulse picking, pump sources, master oscillators and various optical components are described.

A system and method that may enable the generation of highly-efficient, high-power, narrow-linewidth, and tunable light sources from microwave frequencies to mid-infrared wavelengths is disclosed. The light source comprises a nonlinear medium coupled to a multi-modal cavity and a high-energy pump source. The nonlinear medium provides three-wave mixing between modes present in the cavity to generate, for example, terahertz waves. The broadband cavity enables cascading nonlinear processes. By engineering the Q-factors of the cavity's many modes, red-shifted (stokes) cascaded nonlinear processes strongly dominate over their blue-shifted (anti-stokes) counterparts, resulting in a quasi-complete depletion of the pump energy into the THz mode.

Tunable monolithic cavity-based frequency converter pumped by a single-frequency laser where cavity resonance(s) are achieved by independently changing the temperatures of different sections of the crystal, including the periodically poled section and one or more adjacent, non-poled regions. Having independent control of the phase matching temperature and the cavity resonance for a down-converted beam increases the efficiency.

An optical second-harmonic generator (or spontaneous parametric down-converter) includes a microresonator formed of a nonlinear optical medium. The microresonator supports at least two modes that can be phase matched at different frequencies so that light can be converted between them: A first resonant mode having substantially radial polarization and a second resonant mode having substantially vertical polarization. The first and second modes have the same radial order. The thickness of the nonlinear medium is less than one-half the pump wavelength within the medium.

Non-classical light is generated from classical light by providing a non-classical light generation stage with at least one waveguide; inputting classical light into the non-classical light generation stage; and converting at least part of the classical light into non-classical light. The classical light is in a non-fundamental propagation mode of a waveguide of the non-classical light generation stage, and the non-classical light is in a fundamental propagation mode a waveguide of the non-classical light generation stage. The converting does not involve quasi-phase-matching. An input adaptation stage obtains classical light for input into the non-classical light generation stage. In the input adaptation stage, classical light is converted into classical light of a different waveguide propagation mode. A system has a non-classical light generation stage for converting classical light at least partly into non-classical light, and an optical switch and/or an optical phase shifter, arranged on a single optical chip.

A device for a nonlinear optical frequency-conversion of laser radiation comprises a multipass arrangement being arranged such that a laser radiation coupled into the multipass arrangement carries out multiple roundtrips in the multipass arrangement. The device further comprises a nonlinear optical medium-arranged at least partly within the multipass arrangement such that at least in several of the roundtrips the laser radiation coupled into the multipass arrangement passes through the nonlinear optical medium to carry out a nonlinear optical conversion of a part of the laser radiation propagating through the nonlinear optical medium into frequency-converted components based on a second order susceptibility .sup.(2) of the nonlinear optical medium. The device is configured such that the laser radiation- and the frequency-converted components propagate in the multipass arrangement-along a common beam path including at least five passes through the nonlinear optical medium.

Provided is an optical parametric oscillation laser based on I-type quasi-phase matching. The optical parametric oscillation laser comprises a femtosecond laser pumping source (1), an input coupling mirror (3), an Mg:PPLN crystal (4), an output coupling mirror (7) and a beam splitter prism (12), wherein the femtosecond laser pumping source (1) of a synchronous pump, the input coupling mirror (3), the Mg:PPLN crystal (4), the output coupling mirror (7) and the beam splitter prism (12) are sequentially placed. Group velocity mismatching between near-infrared pump light and intermediate infrared signal light in the intermediate infrared optical parametric oscillation laser is eliminated by using the dispersion relationship between the crystal and the temperature and in a manner of adjusting the working temperature of the crystal, so that an optical parametric oscillation process can satisfy phase matching and group velocity matching at the same time, and therefore intermediate infrared ultrashort pulse laser with high power and wide spectrum is obtained.