A difference frequency generation optical transmitter and sum frequency generation optical receiver operating in the mid-infrared wavelength range for use in free space optical satellite communications are described. By using mid-infrared light, the transmitter/receiver can mitigate atmospheric scintillation, scattering, and other non-ideal optical effects in the communication channel. This is achieved through the use of nonlinear optical crystals designed for difference frequency generation in the case of the transmitter and sum frequency generation for the receiver. High-speed modulated communication signals can thus be frequency converted to the mid-infrared wavelength range by a relatively low cost, compact and high-power optical communication system.

In this patent, we teach methods to generate coherent X-ray and UUV rays beams for X ray and UUV microscopes using intense femtosecond pulses resulting the Ultra-Supercontinuum (USC) and Higher Harmonic Generation (HHG) from χ3 and χ.sup.5 media produce from electronic and molecular Kerr effect. The response of n.sub.2 (χ3) and n.sub.4 (χ5) at the optical frequency from instantaneously response of carrier phase of envelope results in odd HHG and spectral broadening about each harmonic on the anti-Stokes side of the pump pulse at wo typically in the visible, NIR, and MIR. From the slower molecular Kerr response on femtosecond to picosecond from orientation and molecular motion on n.sub.2 and n.sub.4 which follow the envelope of optical field of the laser gives rise to extreme broadening without HHG. The resulting spectra extend on the Stokes side towards the IR, RF to DC covering most of the electromagnetic spectrum. These HHG and Super broadening covering UUV to X rays and possibly to gamma ray regime for microscopes.

In this patent, we teach methods to generate coherent X-ray and UUV rays beams for X ray and UUV microscopes using intense femtosecond pulses resulting the Ultra-Supercontinuum (USC) and Higher Harmonic Generation (HHG) from χ3 and χ.sup.5 media produce from electronic and molecular Kerr effect. The response of n.sub.2 (χ3) and n.sub.4 (χ5) at the optical frequency from instantaneously response of carrier phase of envelope results in odd HHG and spectral broadening about each harmonic on the anti-Stokes side of the pump pulse at wo typically in the visible, NIR, and MIR. From the slower molecular Kerr response on femtosecond to picosecond from orientation and molecular motion on n.sub.2 and n.sub.4 which follow the envelope of optical field of the laser gives rise to extreme broadening without HHG. The resulting spectra extend on the Stokes side towards the IR, RF to DC covering most of the electromagnetic spectrum. These HHG and Super broadening covering UUV to X rays and possibly to gamma ray regime for microscopes.

A method for intracavity frequency conversion includes end-pumping a solid-state gain medium in a laser resonator with a pump laser beam to generate an intracavity laser beam circulating in the laser resonator, and frequency-converting a portion of the intracavity laser beam in a nonlinear crystal, located in the laser resonator, to generate a frequency-converted laser beam. The method controls the output power and at least one output beam parameter of the frequency-converted laser beam by adjusting (a) the pump power and (b) a resonator loss imposed on the intracavity laser beam. Taking advantage of both the pump laser beam and the intracavity laser beam contributing to thermal lensing in the gain medium, this control scheme is capable of controlling the output power and the output beam parameter(s) independently of each other.

A method for intracavity frequency conversion includes end-pumping a solid-state gain medium in a laser resonator with a pump laser beam to generate an intracavity laser beam circulating in the laser resonator, and frequency-converting a portion of the intracavity laser beam in a nonlinear crystal, located in the laser resonator, to generate a frequency-converted laser beam. The method controls the output power and at least one output beam parameter of the frequency-converted laser beam by adjusting (a) the pump power and (b) a resonator loss imposed on the intracavity laser beam. Taking advantage of both the pump laser beam and the intracavity laser beam contributing to thermal lensing in the gain medium, this control scheme is capable of controlling the output power and the output beam parameter(s) independently of each other.

A tube preparation step of preparing a resin tube that has a tube wall impregnable with a solution including a fine substance and is made of a light-transmitting resin material, a solution preparation step of preparing a solution that includes a fine fluorescent substance that emits fluorescence or a fine scattering substance that scatters light as an oscillation material and an impregnation step of causing the resin tube to be immersed in the solution and causing the tube wall of the resin tube to be impregnated with the oscillation material, are included.

Methods, systems and methods for reducing temporal coherence of laser systems are described. One example laser system includes a seed laser having a continuous wave output and operable at a first wavelength, a phase modulator positioned to receive laser light from the seed laser and to impart phase modulation to the seed laser. The laser system also includes an optical parametric amplifier positioned to receive phase-modulated laser light at one of its inputs and a pump laser light at another input, and to produce an output beam having spectral characteristics of the phase-modulated laser light that is amplified according to a temporal feature of the pump laser light. In the example laser system, an output of the optical parametric amplifier has a lower temporal coherence compared to the seed laser.

A high repetition rate pulse laser including a linear cavity having a first direction and a second direction opposite to the first direction is disclosed. The pulse laser includes, along the first direction, a first optical component, a gain and Raman medium, an acousto-optic crystal, a first lithium triborate (LBO) crystal and a second optical component. The first optical component allows a pumping light incident in the first direction to transmit therethrough. The gain and Raman medium receives the pumping light from the first optical component, and generates a first infrared base laser light having a first wavelength and a second infrared base laser light having a second wavelength. The acousto-optic crystal receives a radio frequency control signal from a radio frequency controller, wherein the radio frequency control signal has a signal period including a low level period and a high level period.

A compact, portable Raman spectrometer makes fast, sensitive standoff measurements at little to no risk of eye injury or igniting the materials being probed. This spectrometer uses differential Raman spectroscopy and ambient light measurements to measure point-and-shoot Raman signatures of dark or highly fluorescent materials at distances of 1 cm to 10 m or more. It scans the Raman pump beam(s) across the sample to reduce the risk of unduly heating or igniting the sample. Beam scanning also transforms the spectrometer into an instrument with a lower effective safety classification, reducing the risk of eye injury. The spectrometer's long standoff range automatic focusing make it easier to identify chemicals through clear and translucent obstacles, such as flow tubes, windows, and containers. And the spectrometer's components are light and small enough to be packaged in a handheld housing or housing suitable for a small robot to carry.

The present disclosure discloses a method and apparatus for generating an optical frequency comb. The specific generation method comprises: receiving a pump laser that matches a thermally stable state of a nonlinear optical resonant cavity and causing the pump laser to oscillate in the nonlinear optical resonant cavity, such that a Brillouin gain corresponding to the pump laser coincides with a target longitudinal mode in the nonlinear optical resonant cavity; continuously generating a Brillouin laser at the target longitudinal mode in the case that a pump power of the pump laser exceeds a threshold for generating the Brillouin laser; and generating an optical frequency comb by using the Brillouin laser through a Kerr nonlinear four-wave mixing process. According to the technical solution of the present disclosure, the nonlinear optical resonant cavity with the Brillouin gain can generate an optical frequency comb in its thermally stable region. This optical frequency comb not only has good stability, but also has low quantum noise and narrow linewidth characteristics.