An apparatus for generating electromagnetic radiation includes a pump laser so adapted that in operation of the apparatus it generates electromagnetic continuous-wave pump radiation; an optical parametric oscillator which is arranged in the beam path of the pump radiation and has a non-linear optical crystal, and is so adapted that in operation of the apparatus it generates signal and idler radiation from the pump radiation, and a non-linear optical device having a non-linear optical crystal, being arranged at least in a beam path of the signal radiation or idler radiation, and being so adapted that in operation of the apparatus it generates from the signal or idler radiation electromagnetic radiation at a frequency greater than a frequency of the signal or idler radiation. The non-linear optical crystal being heated in a furnace so that the crystal has a temperature gradient in the beam direction of the signal or idler radiation.

The present application discloses a nonlinear optical crystal material, preparation method and application of the nonlinear optical crystal material. The nonlinear optical crystal material has an excellent infrared nonlinear optical performance, whose frequency-doubling intensity can reach 9.3 times of AgGaS.sub.2 with the same particle size, and it meets type-I phase matching; and its laser damage threshold can reach 7.5 times of AgGaS.sub.2 with the same particle size. The nonlinear optical crystal material has important application value in the frequency-converters which can be used for frequency doubling, sum frequency, difference frequency, optical parametric oscillation of laser in mid and far infrared waveband, and the like.

The present application discloses a nonlinear optical crystal material, preparation method and application of the nonlinear optical crystal material. The nonlinear optical crystal material has an excellent infrared nonlinear optical performance, whose frequency-doubling intensity can reach 9.3 times of AgGaS.sub.2 with the same particle size, and it meets type-I phase matching; and its laser damage threshold can reach 7.5 times of AgGaS.sub.2 with the same particle size. The nonlinear optical crystal material has important application value in the frequency-converters which can be used for frequency doubling, sum frequency, difference frequency, optical parametric oscillation of laser in mid and far infrared waveband, and the like.

A device includes: at least one laser element with light emitting points to output fundamental waves in a one-dimensional array; a wavelength converting element to carry out wavelength conversion of the incident fundamental waves, and to output wavelength converted light rays; and an output mirror to reflect the fundamental waves, and to transmit the wavelength converted light rays resulting from the wavelength conversion by the wavelength converting element. The wavelength converting element is disposed between the laser element and the output mirror, and the distance between the position of a waist of the fundamental waves output from the laser element and the output mirror is set in accordance with a Talbot condition under which the adjacent light emitting points cause phase synchronization with each other.

This disclosure provides an optical parametric oscillator, comprising, in a light path, a first lens, a laser crystal, a second lens, a nonlinear optical crystal, and a third lens in this order, wherein an optical parametric oscillation chamber is formed between the second lens and the third lens, and the nonlinear optical crystal is a monoclinic Ga.sub.2S.sub.3 crystal, the space group of the monoclinic Ga.sub.2S.sub.3 crystal is Cc, and the unit cell parameters are a=11.1 Å, b=6.4 Å, c=7.0 Å, α=90°, β=121°, γ=90°, and Z=4.

This disclosure provides an optical parametric oscillator, comprising, in a light path, a first lens, a laser crystal, a second lens, a nonlinear optical crystal, and a third lens in this order, wherein an optical parametric oscillation chamber is formed between the second lens and the third lens, and the nonlinear optical crystal is a monoclinic Ga.sub.2S.sub.3 crystal, the space group of the monoclinic Ga.sub.2S.sub.3 crystal is Cc, and the unit cell parameters are a=11.1 Å, b=6.4 Å, c=7.0 Å, α=90°, β=121°, γ=90°, and Z=4.

The multi wavelength laser device includes a laser light source 10 that emits a plurality of laser lights 20 whose fundamental wavelengths differ from one another, a dispersing element 30 that changes the traveling direction of each of the plurality of laser lights according to the wavelength and the incidence direction, and that emits the laser lights in a state in which the laser lights are superposed on the same axis, and a wavelength conversion element 40 that has a plurality of polarization layers disposed therein and having different periods, and that performs wavelength conversion on the fundamental wave laser lights emitted from the dispersing element 30 and placed in the state in which the laser lights are superposed on the same axis, and emits a plurality of laser lights 50 acquired through the wavelength conversion in a state in which the laser lights are superposed on the same axis.

The multi wavelength laser device includes a laser light source 10 that emits a plurality of laser lights 20 whose fundamental wavelengths differ from one another, a dispersing element 30 that changes the traveling direction of each of the plurality of laser lights according to the wavelength and the incidence direction, and that emits the laser lights in a state in which the laser lights are superposed on the same axis, and a wavelength conversion element 40 that has a plurality of polarization layers disposed therein and having different periods, and that performs wavelength conversion on the fundamental wave laser lights emitted from the dispersing element 30 and placed in the state in which the laser lights are superposed on the same axis, and emits a plurality of laser lights 50 acquired through the wavelength conversion in a state in which the laser lights are superposed on the same axis.

A continuously tunable radio frequency (RF) sensor system is provided. The system includes a pump laser system that includes first and second pump lasers, at least one frequency modulator to modulate frequencies of first and second laser light from the pump lasers to first and second select frequencies, a switch system to selectively pass one of the first and second laser light, an amplifier to amplify the passed laser light, a frequency doubler to double the frequency of the amplified laser light to generate pump light. A laser source lock system is in communication with the pump laser system to ensure a frequency of the pump light is referenced to atoms in a vapor cell and provide a probe light. The pump light and probe light are transmitted through the vapor cell. A detector measures the probe light that passed through the vapor cell.

A continuously tunable radio frequency (RF) sensor system is provided. The system includes a pump laser system that includes first and second pump lasers, at least one frequency modulator to modulate frequencies of first and second laser light from the pump lasers to first and second select frequencies, a switch system to selectively pass one of the first and second laser light, an amplifier to amplify the passed laser light, a frequency doubler to double the frequency of the amplified laser light to generate pump light. A laser source lock system is in communication with the pump laser system to ensure a frequency of the pump light is referenced to atoms in a vapor cell and provide a probe light. The pump light and probe light are transmitted through the vapor cell. A detector measures the probe light that passed through the vapor cell.