Apparatus for providing optical radiation (15), which apparatus comprises an optical input (13), a coupler (2), a first semiconductor amplifier (3), a controller (4), a preamplifier (61), a power amplifier (62) and an output fibre (5), wherein: the optical input (13) is for receiving input optical radiation (14); the optical input (13) is connected in series to the coupler (2), the first semiconductor amplifier (3), the preamplifier (61), the power amplifier (62), and the output fibre (5); the apparatus being characterized in that: the first semiconductor amplifier (3) comprises a waveguide (6) having a low reflecting facet (8); the first semiconductor amplifier (3) is in a double pass configuration such that the low reflecting facet (8) is connected to both the optical input (13) and the preamplifier (61) via the coupler (2); and the controller (4) is configured to cause the waveguide (6) of the first semiconductor amplifier (3) to operate in saturation thereby enabling the first semiconductor amplifier (3) to reduce non-linear effects in the preamplifier (61), the power amplifier (62), and the output fibre (5).

In accordance with an example embodiment, a laser arrangement is provided, the laser arrangement comprising a light source for generating light output; a collimator assembly for collimating the light output from the light source into a pump beam; an optical resonator assembly for generating pulsed output beam based on the pump beam directed thereat; and a beam displacement assembly for laterally shifting the pump beam to adjust the position at which the pump beam meets a surface of the optical resonator assembly.

A kind of all-solid-state high-power slab laser based on phonon band-edge emission, which is comprised of a pumping source, a focusing system, a resonant cavity and a self-frequency-doubling crystal; the said self-frequency-doubling crystal is a Yb-doped RECOB crystal cut into slab shape along the direction of the crystal's maximum effective nonlinear coefficient of its non-principal plane; by changing the cutting direction of the crystal, the phase matching of different wavelengths is realized, thus realizing laser output at the band of 560-600 nm; the said pumping source is a diode laser matrix with a wavelength of 880 nm-980 nm; the input cavity mirror and the output cavity mirror are coated with films to obtain laser output at the band of 560-600 nm; the two large faces of the said self-frequency-doubling crystal is cooled by heat sink and located between the input cavity mirror and the output cavity mirror.

Systems and methods for measuring temperature in an environment by creating a first beam having an energy of about 50 mJ/pulse, and a pulse duration of about 100 ps. A second beam is also created, having an energy of about 2.3 mJ/pulse, and a pulse duration of about 58 ps. The first beam and the second beam are directed into a probe region, thereby expressing an optical output. Properties of the optical output are measured at a sampling rate of at least about 100 kHz, and temperature measurements are derived from the measured properties of the optical output. Such systems and methods can be used to measure temperature in environments exhibiting highly turbulent and transient flow dynamics.

A method and a laser for breaking through the limitation of fluorescence spectrum on laser wavelength is disclosed. The method includes: exciting electrons to a high energy level by pump light, and suppressing an oscillation of radiation light by laser cavity coating, using a laser resonance to enhance a transition probability of an electron-phonon coupling from the high energy level to a multi-phonon coupling level, so as to realize the emission and enhancement of breakthrough fluorescence spectrum and realize the radiation light oscillation, wherein the laser cavity includes an incident mirror, a folding mirror, a tuning element and an exit mirror arranged in sequence along an optical path direction, the laser gain medium is located between an incident mirror and a folding mirror in the laser resonator, and the tuning element is arranged in the laser cavity at a Brewster angle.

A laser system comprising an RE:XAB gain medium within a resonator cavity. X is selected from Ca, Lu, Yb, Nd, Sm, Eu, Gd, Ga, Tb, Dy, Ho, Er, and RE is selected from Lu, Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Pr, Tm, Cr, Ho. The system further comprises a pumping source having optical output directed towards the gain medium. A laser controller operates the pumping source. The system further comprises a heat spreader, the heat spreader in thermal communication with the gain medium through a surface wherein the pump source has optical output incident.

An extra cavity harmonic generator system may produce a round, non-astigmatic third harmonic output beam from a nominally round, non-astigmatic, diffraction limited input fundamental beam. The system may include a second harmonic generation crystal. An input fundamental beam size is expanded in a non-walkoff direction for the SHG crystal at the SHG crystal input face. A higher harmonic generation crystal has an output face oriented at an oblique angle of incidence in a non-walkoff direction for the HHG crystal such that an output higher harmonic beam size is contracted in this direction. Expansion of the input fundamental beam at the SHG crystal input face exceeds reduction of third harmonic beam at the HHG crystal output face.

A solid-state laser system may include first and second solid-state laser units, a wavelength conversion system, an optical shutter, and a controller. The first solid-state laser unit and the second solid-state laser unit may output first pulsed laser light with a first wavelength and second pulsed laser light with a second wavelength, respectively. The controller may perform first control and second control. The first control may cause the first and second pulsed laser light to enter the wavelength conversion system at a substantially coincidental timing, thereby causing the wavelength conversion system to output third pulsed laser light with a third wavelength converted from the first wavelength and the second wavelength, and the second control may prevent the first and second pulsed laser light from entering the wavelength conversion system at the coincidental timing, thereby preventing the wavelength conversion system from outputting the third pulsed laser light.

A laser system includes a nonlinear optical (NLO) crystal, wherein the NLO crystal is annealed within a selected temperature range. The NLO crystal is passivated with at least one of hydrogen, deuterium, a hydrogen-containing compound or a deuterium-containing compound to a selected passivation level. The system further includes at least one light source, wherein at least one light source is configured to generate light of a selected wavelength and at least one light source is configured to transmit light through the NLO crystal. The system further includes a crystal housing unit configured to house the NLO crystal.

Systems and methods for measuring temperature in an environment by creating a first beam having an energy of about 50 mJ/pulse, and a pulse duration of about 100 ps. A second beam is also created, having an energy of about 2.3 mJ/pulse, and a pulse duration of about 58 ps. The first beam and the second beam are directed into a probe region, thereby expressing an optical output. Properties of the optical output are measured at a sampling rate of at least about 100 kHz, and temperature measurements are derived from the measured properties of the optical output. Such systems and methods can be used to measure temperature in environments exhibiting highly turbulent and transient flow dynamics.