A fiber gain medium provided by a rare-earth doped fiber (10) is contained in a first resonant cavity by end reflectors (12, 18). The reflector (12) is wavelength selective to limit the frequency band of the first resonant cavity. The first resonant cavity also contains a second resonant enhancement cavity (16) with multiple transmission bands lying within the first resonant cavity's frequency band. Multiple standing wave modes of the first resonant cavity lie within both the frequency band of the first resonant cavity and the transmission bands of the second resonant cavity, and it is these standing wave modes that support laser action when the rare-earth doped fiber is suitably pumped by pump lasers (40).

An optical apparatus to provide several light bands on a single coaligned beam line or axis. The apparatus generally comprises five main components: a pump, a fold mirror, an input coupler, a nonlinear optical (NLO) crystal, and an output coupler. Alternatively, the present invention may comprise four main components, namely, a pump, an acute porro prism, a NLO crystal, and an input-output coupler. The pump input beam makes two passes through the nonlinear optical crystal and generates two new colors, having different wavelengths, during each pass through the nonlinear optical crystal.

An optical arrangement for enlarging spectral bandwidths by nonlinear self-phase modulation for shortening ultrashort pulses using a multipass cell and a nonlinear medium. The nonlinear medium is arranged within the multipass cell, and a laser beam having ultrashort pulses passes through the nonlinear medium multiple times. The laser beam is coupled into the multipass cell by way of a shaping optical unit. The laser beam is shaped into an astigmatic beam and coupled into the multipass cell by way of the shaping optical unit.

An optical apparatus comprising: a source and a loop. The source generates a pump. The resonating cavity of the source includes: a gain medium; and a tunable filter for selecting a wavelength. The loop comprises: an input coupler; a waveguide; and an output coupler. The input coupler receives the pump and a signal and outputs the pump and the signal into the waveguide In the waveguide, energy in the pump is transferred into energy in the signal while a relative center position of the signal is crossing a center position of the pump in a first direction while both are passing through the waveguide and into the output coupler. The output coupler r outputs a first portion of the signal and a second portion of the signal is fed into the input coupler as the signal, completing the loop.

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.

The present disclosure relates to a scalable bulk monolayer MoS.sub.2 (BM-MoS.sub.2) thin film for highly efficient SHG. The solution-assembled centimeter-scale BM-MoS.sub.2 thin films consist of alternating monolayer MoS.sub.2 atomic crystals and organic molecular layers that prevent interlayer coupling, thus preserving monolayer-like physical properties while achieving significantly increased optical cross-sections. The SHG studies demonstrate that the BM-MoS.sub.2 exhibits a giant SHG that is 126 times higher than monolayer MoS.sub.2 and 21 times higher than the single crystalline GaAs wafer, a material with the highest second-order NLO susceptibility among known bulk semiconductors. The facile assembly of BM-MoS.sub.2 thin films with highly efficient SHG offers a scalable pathway for developing ultrathin, efficient, and cost-effective NLO devices.

An optical frequency comb generation system comprises an optical waveguide, which in turn comprises a length defining an elongated direction of the waveguide, and first and second reflector portions along the length and arranged to reflect light within the waveguide. A weak reflector portion is between the first and second reflector portions along the length of the waveguide and has a reflectivity less than the reflectivity of the first and second reflector portions. The weak reflector portion is arranged to shift wavelengths of resonances of light within the waveguide.

For adapting optical properties of a continuous body arranged in a resonator cavity and comprising a nonlinear optical material to light of two different wavelengths passing through the continuous body along an optical axis, the continuous body having a total length along the optical axis, a spatially constant temperature is adjusted in a first region of the continuous body, the first region extending over at least 20% of the total length, and a temperature gradient is adjusted in a second region of the continuous body, the second region neighboring the first region and extending over at least 10% of the total length. The temperature gradient may be selected such as to achieve resonance of the light of both wavelengths in the resonator cavity.