A laser device configured to emit a coherent optical radiation is provided. The laser device has an amplifier system having a single interferometric optical amplification arrangement or a plurality of interferometric optical amplification arrangements in series, an optical return path of an optical beam emerging from the amplifier system and entering the amplifier system to form an optical ring resonant structure, and a radiation output for extracting a portion of the optical beam emerging from the amplifier system and deliver the extracted portion of the optical beam emerging from the amplifier system as output laser radiation of the laser device.

A method for generating femtosecond vortex beams with high spatial intensity contrast, where a noncollinearly pumped HG beam femtosecond laser generates femtosecond HG beam and a cylindrical lens mode converter converts the femtosecond HG beam to femtosecond LG vortex beam. The HG beam femtosecond laser comprises a pump source, a gain medium, a saturable absorption mirror as mode-locker, and an output coupler with a noncollinear angle between the laser beam and the pump beam in the gain medium, which enables the laser to generate pure, order-tunable femtosecond HG beams. Femtosecond vortex beams obtained after the cylindrical lens converter have high-intensity-contrast, and are topological charge-tunable.

A device may include a first photodetector to generate a first current based on an optical power of an optical beam. The device may include a beam splitter to split a portion of the optical beam into a first beam and a second beam. The device may include a wavelength filter to filter the first beam and the second beam. The wavelength filter may filter the second beam differently than the first beam based on a difference between an optical path length of the first beam and an optical path length of the second beam through the wavelength filter. The device may include second and third photodetectors to respectively receive, after the wavelength filter, the first beam and the second beam and to generate respective second currents.

A narrow band laser apparatus may include: a laser resonator; a pair of discharge electrodes; a power supply; a first wavelength measurement device configured to output a first measurement result; a second wavelength measurement device configured to output a second measurement result; and a control unit. The control unit calibrates the first measurement result, based on a difference between the second measurement result derived when the control unit controls the power supply to apply a pulsed voltage to the pair of discharge electrodes with a first repetition frequency and the second measurement result derived when the control unit controls the power supply to apply the pulsed voltage to the pair of discharge electrodes with a second repetition frequency, the second repetition frequency being higher than the first repetition frequency.

A multiple frequency comb source apparatus (100) for simultaneously creating a first laser pulse sequence representing a first frequency comb (1) and at least one further laser pulse sequence representing at least one further frequency comb (2), wherein at least two of the first and at least one further pulse sequences have different repetition frequencies, comprises a laser resonator device (10) comprising multiple resonator mirrors including first end mirrors EM.sub.1,OC.sub.1 providing a first laser resonator (11), a laser gain medium (21, 22) being arranged in the laser resonator device (10), and a pump device (30) being arranged for pumping the laser gain medium (21), wherein the laser resonator device (10) is configured for creating the first and at least one further laser pulse sequences by pumping and passively mode-locking the laser gain medium (21), the resonator minors of the laser resonator device (10) include further end minors EM.sub.2, OC.sub.2 providing at least one further laser resonator (12), the first laser resonator (11) and the at least one further laser resonator (12) share the laser gain medium (21), resonator modes of the first laser resonator (11) and the at least one further laser resonator (12) are displaced relative to each other, wherein the resonator modes are located in the laser gain medium (21) at separate beam path spots, and at least one of the first and further end minors EM.sub.1, EM.sub.2, OC.sub.1, OC.sub.2 is adjustable so that the repetition frequency of at least one of the first and at least one further laser pulse sequences can be set independently from the repetition frequency of the other one of the first and at least one further laser pulse sequences. Furthermore, a spectroscopic measuring method, a spectroscopy apparatus and a multiple frequency comb generation method are described.

A pulse stretching fiber oscillator (or laser cavity) may comprise a chirped fiber Bragg grating (CFBG) and an optical circulator arranged such that a first portion of a beam that is transmitted through the CFBG continues to propagate through the laser cavity while a second portion of the beam that is reflected from the CFBG is stretched and chirped by the CFBG and directed out of the laser cavity by the optical circulator. Accordingly, a configuration of the CFBG and the optical circulator in the laser cavity may enable pulse stretching contemporaneous with outcoupling, which may prevent deleterious nonlinear phase from accumulating prior to stretching.

Apparatus and methods for producing ultrashort optical pulses are described. A high-power, solid-state, passively mode-locked laser can be manufactured in a compact module that can be incorporated into a portable instrument. The mode-locked laser can produce sub-50-ps optical pulses at a repetition rates between 200 MHz and 50 MHz, rates suitable for massively parallel data-acquisition. The optical pulses can be used to generate a reference clock signal for synchronizing data-acquisition and signal-processing electronics of the portable instrument.

A pulse stretching fiber oscillator (or laser cavity) may comprise a chirped fiber Bragg grating (CFBG) and an optical circulator arranged such that a first portion of a beam that is transmitted through the CFBG continues to propagate through the laser cavity while a second portion of the beam that is reflected from the CFBG is stretched and chirped by the CFBG and directed out of the laser cavity by the optical circulator. Accordingly, a configuration of the CFBG and the optical circulator in the laser cavity may enable pulse stretching contemporaneous with outcoupling, which may prevent deleterious nonlinear phase from accumulating prior to stretching.

An optical element for a deep-ultraviolet light source includes a crystalline substrate; a coating on an exterior surface of the crystalline substrate, the coating having a thickness along a direction that extends away from the exterior surface; and a structure on and/or in the coating, the structure including a plurality of features that extend away from the crystalline substrate along the direction. The features include an amorphous dielectric material and are arranged such that an index of refraction of the structure varies along the direction.

In various embodiments, laser resonator modules produce output beams via manipulation of input beams on opposite sides of the module. The input beams are emitted by one or more beam emitters that may be cooled using a liquid coolant cavity. The liquid coolant cavity may be isolated from optical elements utilized to manipulate the input beams, at least in part, by an isolation wall protruding from the base plate of the resonator module.