A laser processing apparatus for producing a GaN wafer from a GaN ingot includes a laser beam irradiating unit configured to apply a laser beam having a wavelength capable of passing through the GaN ingot held by a chuck table. The laser beam irradiating unit includes a laser oscillator configured to oscillate the laser beam. The laser oscillator includes a seeder configured to oscillate a high-frequency pulsed laser, a thinning-out unit configured to thin out high-frequency pulses oscillated by the seeder at a predetermined repetition frequency, and generate one burst pulse with a plurality of high-frequency pulses as sub-pulses, and an amplifier configured to amplify the generated burst pulse.

Embodiments of the disclosure provide a system for controlling power of laser lights emitted by an optical sensing device. The system includes at least one storage device configured to store instructions and at least one processor communicatively coupled to the at least one storage device and configured to execute the instructions to perform operations. The operations include detecting an object within a field of view of the optical sensing device based on a reflected laser signal received by the optical sensing device, determining a distance of the object from the optical sensing device, determining a value indicating a total power of one or more laser beams to be incident on an aperture at the distance, and comparing the value with a predetermined tolerance value. The operations also includes adjusting a laser emission scheme to reduce the total power when the value is greater than the predetermined tolerance value.

Systems and methods are disclosed for selectively passing or blocking laser electromagnetic energy. A laser system comprises a shutter, whereby when the shutter is rotated one or more open areas of the shutter and one or more solid areas of the shutter are alternately positioned in a path of electromagnetic radiation emitted by the laser. The shutter may operate in different modes, including allowing all laser pulses to pass through in whole or in part, blocking all laser pulses from passing through, and alternately allowing and blocking laser pulses. In some embodiments, the shutter is controlled to allow only a part of each selected laser pulse to pass through. A laser system comprises a waveplate rotatable into different positions corresponding to different operating modes. The different operating modes may include allowing part and blocking part of the laser electromagnetic radiation.

A method of patterning lithographic substrates that includes using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates. The method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly, and applying variable attenuation to EUV radiation that has been output by the free electron laser in order to further control the power of EUV radiation delivered to the lithographic apparatus.

In one aspect, the present disclosure describes a fiber laser system for the generation and delivery of femtosecond (fs) pulses in multiple wavelength ranges. For improved versatility in multi-photon microscopy, an example of a dual wavelength fiber system based on Nd fiber source providing gain at 920 and 1060 nm is described. An example of a three-wavelength system is included providing outputs at 780 nm, 940 nm, and 1050 nm. The systems include dispersion compensation so that high quality fs pulses are provided for applications in microscopy, for example in multiphoton microscope (MPM) systems.

An optical pulse generator arranged to generate an initial sequence of optical pulses having an initial inter-pulse period; and an optical pulse burst formation apparatus including: an interleaving stage to receive an initial sequence of optical pulses having an initial inter-pulse period, including: an optical splitter to power split received optical pulses, thereby generating a first and second replica sequences of optical pulses; a first optical arm to receive the first replica sequence, having a first optical path length; and a second optical arm to receive the second replica sequence, having a second optical path length, different to the first optical path length by a path length difference; and an optical combiner arranged to combine the first replica sequence of pulses and the second replica sequence of delayed pulses to form an output sequence of optical pulse bursts.

Disclosed is a system and method for remote sensing, surface profiling, object identification, and aiming based on two-photon population inversion and subsequent photon backscattering enhanced by superradiance using two co-propagating pump waves. The present disclosure enables efficient and highly-directional photon backscattering by generating the pump waves in properly pulsed time-frequency modes, proper spatial modes, with proper group-velocity difference in air. The pump waves are relatively delayed in a tunable pulse delay device and launched to free space along a desirable direction using a laser-pointing device. When the pump waves overlap in air, signal photons will be created through two-photon driven superradiant backscattering if target gas molecules are present. The backscattered signal photons propagate back, picked using optical filters, and detected. By scanning the relative delay and the launching direction while the signal photons are detected, three-dimensional information of target objects is acquired remotely.

A WDM seed beam source for a fiber laser amplifier system that includes a number of master oscillators that generate seed beams at different wavelengths and a spectral multiplexer that multiplexes all of the seed beams onto a single fiber. An EOM modulates the combined seed beams on the single fiber and a spectral demultiplexer then separates the modulated seed beams into their constituent wavelengths on separate fibers before the seed beams are amplified and spectrally combined. The fiber laser amplifier system includes a separate fiber amplifier that amplifies the separated seed beams, an emitter array that directs the amplified beams into free space, beam collimating optics that focuses the uncombined beams, and an SBC grating responsive to the collimated uncombined beams that spatially combines the collimated uncombined beams.

A coherently beam combining (CBC) fiber laser amplifier system including 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 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 and cause the profile to taper to a lower value at a perimeter of each input array cell. 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.

An embodiment of the present invention provides a continuous-wave terahertz generation and detection device using a photomixing technique, the device including: first and second light source units configured to output continuous-wave laser light sources, which have single wavelength and different frequencies, to generate optical signals; a first electro-optic phase modulator configured to shift a frequency of the optical signal generated by the first light source unit, and a second electro-optic phase modulator configured to shift a frequency of the optical signal generated by the second light source unit; a first optical amplifier configured to receive and amplify the optical signal whose frequency is shifted by the first electro-optic phase modulator and the optical signal generated by the second light source unit, and a second optical amplifier configured to receive and amplify the optical signal whose frequency is shifted by the second electro-optic phase modulator and the optical signal generated by the first light source unit; an opto-electronic converter configured to convert the optical signal amplified by the first optical amplifier into a terahertz wave; a photomixer configured to mix the optical signal amplified by the second optical amplifier and the terahertz wave generated by the opto-electronic converter and convert the mixed signal into an electrical signal; a photodetector configured to combine the optical signals transferred from the first and second optical amplifiers and convert the combined optical signal into an electrical signal; and a filter unit configured to filter the electrical signal passing through the photodetector, wherein the electrical signal obtained through the photodetector is compared with the electrical signal obtained by the photomixer, and phase noise having the same frequency is removed.