A resonant cavity and a method for manufacturing the same are provided. The resonant cavity includes a first reflective surface and a second reflective surface, each of the first and second reflective surfaces providing a phase shift of a reflected electric field component of light waves oscillating along a first principal axis that differs by about π relative to a phase shift of a reflected electric field component of light waves oscillating along a second principal axis that is normal to the first principal axis. At least one of the first and second reflective surfaces having diattenuation. The first principal axis of the first reflective surface is set rotated relative to the first principal axis of the second reflective surface by about an angle α.sub.0 between an unbroken parity-time symmetric region and a broken parity-time symmetric region. As a result, spatial hole burning and dual mode operation can be eliminated.

A master oscillator configured as a seed laser for a laser optical module includes a reduced size, temperature controlled non-planar ring oscillator, a piezo-electric transducer mounted on the non-planar ring oscillator, a pump laser diode, and coupling optics configured to couple a laser output of the pump laser diode to an end face of the non-planar ring oscillator. The pump laser diode may operate as a single-mode pump.

A method and system for combining two or more optical fields is disclosed. A first continuous-wave high powered output field generated by a solid-state master laser is injected into a first solid state optical amplifier to produce a single output field from the laser system that exhibits a high phase-coherence with the output field of the master laser. The power of the output field equals the sum of powers of the master laser and that generated by the first optical amplifier, while exhibiting similar beams characteristics to that produced by the output field of the master laser i.e. it exhibits low noise, in a single transverse and longitudinal mode Gaussian beam, and has a single polarisation. The laser system is highly scalable in that N optical amplifiers may be located in series with the master laser to provide a single low noise, high power output field.

A laser light source includes: a resonance unit with a light emitter; and an optical negative feedback unit. The resonance unit includes: a first waveguide; a first reflector to input the reflected light to the first waveguide; a second waveguide; a second reflector connected to the second waveguide; and a ring resonator between the first waveguide and the second waveguide. The light from the first reflector is blocked from the ring resonator and partially transmitted to a first end of the first waveguide opposite to a second end connected to the light emitter and the first reflector. The optical negative feedback unit includes: a third waveguide to which the light transmitted to the first end of the first waveguide is inputted; and a third reflector connected to the third waveguide. The light from the third reflector is inputted to the first waveguide via the third waveguide.

A device and a method for measuring thermal load caused by excited state absorption in laser gain crystal are disclosed. Thermal focal lengths on the tangential and sagittal planes of the laser gain crystal are obtained by obtaining the threshold when the pump power is decreased, the optimal operating point, and cavity parameters of the single-frequency laser. Individual ABCD matrices of the laser gain crystal on the tangential plane and the sagittal plane are obtained based on thermal focal length. The thermal load corresponding to the threshold when the pump power is decreased, the ESA thermal load corresponding to the threshold when the pump power is decreased, and the ESA thermal load at the optimal operating point are obtained

A device and a method for measuring a thermal load caused by energy transfer upconversion in a laser gain crystal. Increasing the pump power multiple times so that the power meter obtains multiple thresholds for a single-frequency laser; obtaining an average pump threshold of the output laser; obtaining cavity parameters of the single-frequency laser; obtaining thermal focal lengths on the tangential and sagittal planes of the laser gain crystal inside the single-frequency laser; obtaining individual ABCD matrices of the laser system on the tangential and the sagittal planes; obtaining a thermal load at the threshold based on the ABCD transfer matrix of the laser gain crystal on the tangential plane, the ABCD transfer matrix of the laser gain crystal on the sagittal plane, and the average pump threshold of the laser system; obtaining a thermal load caused by ETU at threshold based on the thermal load at the threshold.

A laser system includes a resonant laser cavity configured to output a laser signal. The system also includes a utility waveguide configured to receive the laser signal from the laser cavity. The utility waveguide includes a perturbation region that is external to the laser cavity and receives the laser signal from the laser cavity and outputs a laser beam. The perturbation region includes one or more perturbation structures that each causes one or more perturbation(s) in the index of refraction of the utility waveguide. The perturbation structures are selected to provide optical feedback to the resonant laser cavity such that a power versus wavelength distribution in the laser beam is different from the power versus wavelength distribution that would be in the laser signal in the absence of the perturbation structures.

An apparatus may include a diode-pumped solid-state laser oscillator configured to output a pulsed laser beam, a modulator configured to modify an energy and a temporal profile of the pulsed laser beam, and an amplifier configured to amplify an energy of the pulse laser beam. A modified and amplified beam to laser peen a target part may have an energy of about 5J to about 10 J, an average power (defined as energy (J)frequency (Hz)) of from about 25 W to about 200 W, with a flattop beam uniformity of less than about 0.2. The diode-pumped solid-state oscillator may be configured to output a beam having both a single longitudinal mode and a single transverse mode, and to produce and output beams at a frequency of about 20 Hz.

A single longitudinal mode ring Raman laser including: a pump source outputting a pump light power, resonantly coupled to a first ring resonator; a optical measurement and piezo-actuator for stabilising the resonant coupling of the pump light power to a first ring resonator; a first ring resonator including a Raman gain medium, wherein the Raman gain medium receives the pump light power and undergoes Raman lasing generating resonated Stokes power at the corresponding Stokes output wavelength; the first ring resonator acting as a feedback loop for the pump light power and the resonated Stokes power and outputting a portion of the Stokes power as the laser output.

Provided is a laser device that includes a laser chamber in which a pair of discharge electrodes are disposed; a line narrowing optical system including a grating disposed in a position outside the laser chamber; a beam expander optical system that increases a diameter of a light beam, outputted from the laser chamber and traveling toward the grating, in a first direction parallel to a discharge direction between the discharge electrodes and in a second direction orthogonal to the discharge direction; and a holding platform that is formed as a component separate from the laser chamber and the grating, holds the beam expander optical system, and forms along with the beam expander optical system a beam expander unit.