A laser apparatus may include a master oscillator, a plurality of amplifiers, a photodetector device configured to detect a light beam traveling back along a laser beam path, and a controller. The photodetector device may include a first photodetector configured to detect energy of a light beam traveling back along the laser beam path and a second photodetector configured to detect power of the light beam traveling back along the laser beam path. The controller may be configured to determine that a return beam is generated when the intensity of the energy detection signal exceeds a first threshold. The controller may be configured to determine that a self-oscillation beam is generated when the intensity of the power detection signal exceeds a second threshold.

A laser apparatus may include a master oscillator, a plurality of amplifiers, a photodetector device configured to detect a light beam traveling back along a laser beam path, and a controller. The photodetector device may include a first photodetector configured to detect energy of a light beam traveling back along the laser beam path and a second photodetector configured to detect power of the light beam traveling back along the laser beam path. The controller may be configured to determine that a return beam is generated when the intensity of the energy detection signal exceeds a first threshold. The controller may be configured to determine that a self-oscillation beam is generated when the intensity of the power detection signal exceeds a second threshold.

A gas laser according to an embodiment includes a gas serving as a laser medium, a thermal radiation source having wavelength selectivity and configured to emit excitation light for excitation of the gas by thermal radiation, and an optical resonator for causing emission light emitted from the gas in response to the excitation light to resonate.

A gas laser according to an embodiment includes a gas serving as a laser medium, a thermal radiation source having wavelength selectivity and configured to emit excitation light for excitation of the gas by thermal radiation, and an optical resonator for causing emission light emitted from the gas in response to the excitation light to resonate.

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

The disclosed invention relates to a COIL based defense system which stays at an altitude of higher than 17 km. The defense system is comprised of a high-altitude airship which carries a COIL in which gases flow along the optical axis with several exit ports. Since the COIL can operate without a vacuum pump, it can be lightweighted.

The disclosed invention relates to a COIL based defense system which stays at an altitude of higher than 17 km. The defense system is comprised of a high-altitude airship which carries a COIL in which gases flow along the optical axis with several exit ports. Since the COIL can operate without a vacuum pump, it can be lightweighted.

The disclosed invention relates to a COIL based defense system which stays at an altitude of higher than 17 km. The defense system is comprised of a high-altitude airship which carries a COIL in which gases flow along the optical axis with several exit ports. Since the COIL can operate without a vacuum pump, it can be lightweighted.

The disclosed invention relates to a COIL based defense system which stays at an altitude of higher than 17 km. The defense system is comprised of a high-altitude airship which carries a COIL in which gases flow along the optical axis with several exit ports. Since the COIL can operate without a vacuum pump, it can be lightweighted.

Laser amplification utilizing plasma confinement of a gas laser gain media is described. The gas laser gain media is compressed into plasma utilizing a self-reinforcing magnetic field referred to a plasma pinch (e.g., a flow stabilized z-pinch). In the pinch, the gas laser gain media is compressed to a high density, which improves the gain of the media. Coherent light is transmitted through the plasma pinch, which is amplified by the plasma pinch.