A disk resonator is pumped by counterpropagating pump signals to produce corresponding counterpropagating Brillouin laser signals. The pump laser optical frequencies are separated by a frequency offset Δν.sub.P but excite the same nominal resonator optical mode; the Brillouin laser optical frequencies are separated by a beat frequency Δν.sub.L with 0<Δν.sub.L<Δν.sub.P. A photodetector receives the Brillouin laser signals and produces an electrical signal at the beat frequency Δν.sub.L. The frequency offset Δν.sub.P can be large so enough to prevent locking of the Brillouin laser signals onto a common Brillouin laser frequency. A signal processing system derives from the beat frequency Δν.sub.L an estimated angular velocity component of the disk optical resonator about an axis substantially perpendicular to the disk optical resonator.

A laser stabilization system and method are provided. The laser stabilization system includes: a laser configured to produce a laser light signal at a target frequency; a phase modulator configured to apply a phase modulation to the laser light signal to produce a phase modulated laser light signal; a stable optical resonator configured to receive the phase modulated laser light signal and return a light signal; a light detection system configured to receive the light signal from the stable optical resonator and produce an amplitude modulated electrical signal based on the light signal; and a digital domain circuit configured to generate a control signal based on the amplitude modulated electrical signal.

A laser system according to the present disclosure includes: a laser apparatus configured to emit a laser beam; a transmission optical system disposed on a path between the laser apparatus and a target supplied into an EUV chamber in which EUV light is generated; a reflection optical system configured to reflect, toward the target, the laser beam from the transmission optical system; a first sensor configured to detect the laser beam traveling from the laser apparatus toward the reflection optical system; a second sensor configured to detect return light of the laser beam reflected by the reflection optical system and traveling backward to the laser apparatus; and a control unit configured to determine that the reflection optical system is damaged when no anomaly of the laser beam is detected and a light amount of the return light exceeds a predetermined light amount value.

A frequency stabilizing system for high precision single-cavity multi-frequency comb includes a single-cavity multi-comb pulse oscillator, a frequency detection system, and a frequency feedback control system. The single-cavity multi-comb pulse oscillator is configured to output mode-locked pulse trains with a certain repetition rate difference at two or more central wavelengths. The frequency detection system is configured to detect the frequency signal, and output the corresponding electrical signal. The frequency feedback control system is configured to process the electrical signal from the frequency detection system, and transmit it to the frequency response component in the single-cavity multi-comb pulse oscillator to control a strain of the frequency response component, so as to realize feedback control on the frequency (repetition rate, repetition rate difference, and carrier envelope offset frequency) of the mode-locked pulse trains.

Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.

Multi-Channels coherent beam combining (CBC) using a mechanism for phase and/or polarization locking that uses a reference optical beam and an array of optical detectors each detector being configured and located to detect overall intensity of an optical interference signal caused by interfering of the reference beam and a beam of the respective channel, where the fast intensity per-channel detection allows simultaneous and quick phase/polarization locking of all channels for improving beam combining system performances.

A sensing method for in-situ non-perturbing measurement of characteristics of laser beams at the exit of the laser beam delivery fiber tips include measuring power of a laser beam transmitted through delivery fiber tip in fiber-optics systems. A sensing devices for in-situ non-perturbing sensing and control of multiple characteristics of laser light transmitted through light delivery fiber tips includes a fiber-tip coupler comprised of a shell with enclosed delivery fiber having a specially designed angle-cleaved endcap and one or several tap fibers that are specially arranged and assembled at back side of the endcap and other variations. Methods and system architectures for in-situ non-perturbing control of characteristics of laser beams at the exit of the laser beam delivery fiber tips include fiber-tip couplers and sensing modules that receive laser light from tap fibers, and systems for optical processing to enhance light characteristics suitable for in-situ measurement.

A hybrid coherent beam combining (CBC) and spectral beam combining (SBC) fiber laser amplifier system including a beam shaper array assembly and a beam source that provides a plurality of beams having a low fill factor profile. The assembly includes an input beam shaper array having a plurality of rectilinear input cells positioned adjacent to each other that are shaped to cause the beam to expand as it propagates away from the input array to be converted from the low fill factor profile to a high fill factor profile. The assembly further includes an output beam shaper array having a plurality of output cells positioned adjacent to each other that are shaped to cause the beam to stop expanding so that the output array provides a plurality of adjacent beams with minimal overlap and a minimal gap between the beams.

A system and method for fabricating an optical element. The method includes welding an array of fibers to the optical element, measuring an angle error and a position error of each fiber, calculating a correction for each fiber for the angle error and the position error and correcting the angle and position of each fiber using the calculated corrections.

A sensing method for in-situ non-perturbing measurement of characteristics of laser beams at the exit of the laser beam delivery fiber tips include measuring power of a laser beam transmitted through delivery fiber tip in fiber-optics systems. A sensing devices for in-situ non-perturbing sensing and control of multiple characteristics of laser light transmitted through light delivery fiber tips includes a fiber-tip coupler comprised of a shell with enclosed delivery fiber having a specially designed angle-cleaved endcap and one or several tap fibers that are specially arranged and assembled at back side of the endcap and other variations. Methods and system architectures for in-situ non-perturbing control of characteristics of laser beams at the exit of the laser beam delivery fiber tips include fiber-tip couplers and sensing modules that receive laser light from tap fibers, and systems for optical processing to enhance light characteristics suitable for in-situ measurement.