A femtosecond pulse laser apparatus includes a pump light source configured to provide a pump light, a gain medium configured to obtain a gain of a laser light using the pump light, a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium, an output mirror configured to transmit a portion of the laser light and reflect the other portion of the laser light to the gain medium, a mode locking portion configured to generate a femtosecond pulse of the laser light, and an acoustic wave generator configured to provide an acoustic wave into the gain medium so as to adjust self-phase modulation of the laser light.

A compact laser source and a single sideband modulator used therein is disclosed. The compact laser source includes a seed laser and one or more channels, with each channel generating one or more output laser beams having corresponding different wavelengths. The compact laser source can be formed in whole or in part on a single optical motherboard to thereby minimize space and power requirements. By employing the disclosed single sideband modulator, harmonics in the generated output laser beams can be minimized. The compact laser source finds application in an atom interferometer (AI) system, which may be used to measure gravity, acceleration, or rotation of the AI system.

Optical frequency combs are used for a wide range of applications, some of which require precise control of the amplitude and phase of individual comb teeth. A technique is provided for tooth-level optical frequency comb control. A frequency comb may include a plurality of comb teeth that are separated from one another by a comb frequency spacing. This technique includes generating a train of control pulses, each of the control pulses being frequency-locked to a corresponding tooth of an optical frequency comb to be controlled. The tooth-level control of the frequency comb is enabled via stimulated Brillouin scattering using the train of control pulses.

A system for determining an absolute carrier-envelope phase (CEP) of ultrashort laser pulses includes a laser system for generating a laser beam including ultrashort optical pulses of a duration of less than 10 fs, an ultrabroadband quarter-wave plate configured to polarize the laser beam, and a gas jet emitting a continuous jet stream into the laser beam. The system includes focusing optics to adjust a focal spot of the laser beam to the gas jet, and a detector arrangement including a beam block and a microchannel plate (MCP) imaging detector, wherein the laser beam is directed to the detector arrangement. The method involves using angular streaking to determine the absolute CEP of both elliptically and linearly polarized light.

A laser apparatus according to the present disclosure includes an excitation light source configured to output excitation light, a laser crystal disposed on an optical path of the excitation light, a first monitor device disposed on an optical path of transmitted excitation light after having transmitted through the laser crystal to monitor the transmitted excitation light, a temperature adjustment device configured to adjust a temperature of the excitation light source to a constant temperature based on a temperature command value, and a controller configured to change the temperature command value based on a result of monitoring by the first monitor device.

A method includes driving, while producing a burst of pulses at a pulse repetition rate, a spectral feature adjuster among a set of discrete states at a frequency correlated with the pulse repetition rate; and in between the production of the bursts of pulses (while no pulses are being produced), driving the spectral feature adjuster according to a driving signal defined by a set of parameters. Each discrete state corresponds to a discrete value of a spectral feature. The method includes ensuring that the spectral feature adjuster is in one of the discrete states that corresponds to a discrete value of the spectral feature of the amplified light beam when a pulse in the next burst is produced by adjusting one or more of: an instruction to the lithography exposure apparatus, the driving signal to the spectral feature adjuster, and/or the instruction to the optical source.

A laser apparatus according to an aspect of the present disclosure includes a laser oscillator that outputs pulsed laser light, a deformable mirror including a deformer that deforms a reflective surface, a first processor that drives the deformer during the period for which the reflective surface reflects the pulsed laser light, a homogenizer that homogenizes the pulsed laser light reflected off the deformable mirror, and a spectrum measuring instrument that measures the spectrum of the pulsed laser light homogenized by the homogenizer.

An exposure method includes reading data representing a relationship between a first parameter relating to an energy ratio between energy of first pulsed laser light having a first wavelength and energy of second pulsed laser light having a second wavelength longer than the first wavelength and a second parameter relating to a sidewall angle of a resist film that is the angle of a sidewall produced when the resist film is exposed to the first pulsed laser light and the second pulsed laser light, and determining a target value of the first parameter based on the data and a target value of the second parameter; and exposing the resist film to the first pulsed laser light and the second pulsed laser light by controlling a narrowed-line gas laser apparatus to output the first pulsed laser light and the second pulsed laser light based on the target value of the first parameter.

A system has fiber amplifiers that amplify a seed signal into a high power signal. Control circuity drives the fiber amplifiers. An auxiliary broad-linewidth signal can be selectively introduced to mitigate the onset of Stimulated Brillouin Scattering (SBS) when the primary input seed source does not meet the requirements of power and/or linewidth. To determine whether to mitigate SBS, an input photodiode can detect the seed signal, and the control circuity can detect an operational parameter associated with a detected signal indicative of an onset of SBS on the optical path. In response to the detection, the control circuitry introduces an auxiliary broad-linewidth signal from a broad-linewidth source, which can mitigate the onset of SBS on the optical path.

Methods and devices are described for performing an all-phase measurement of an ultra-fast laser pulse having a spectral range of greater than one octave. The ultra-fast laser pulse may be split into a first beam comprising a fundamental light with a wavelength λ.sub.0 and a second beam comprising a light with a wavelength 2λ.sub.0. The light with the wavelength 2λ.sub.0 may be frequency doubled to a light with a wavelength λ.sub.0 to generate an interference with the fundamental light. Fourier transform may be performed on an interference spectrum of the interference, and a relative envelope delay (RED) between the fundamental light and the frequency doubled light and a carrier envelope phase (CEP) may be acquired based on a result of the Fourier transform.