Laser amplifier apparatus 100 includes gain medium 10 for receiving seed pulse(s) 2 and pump pulse(s) 3 and for emitting laser pulse(s) 1, resonator device 20 including gain medium and resonator mirrors spanning resonator beam path 25 with multi-pass geometry, coupler arrangement 30 for coupling seed pulse(s) and pump pulse(s) to resonator device and coupling output laser pulse(s) out of resonator device, and gain medium cooling device 40A. Resonator mirrors include first and second telescope mirrors 21, 22 with mutual distance and common focal section therebetween and defining optical axis z of resonator device, and first and second groups of end mirrors 23, 24 between mirrors 21 and 22 for forming path 25, wherein end mirrors are on ring-shaped section surrounding optical axis z, and resonator are arranged such that emitting sections of the gain medium are imaged in themselves. A method of amplifying laser pulses is also described.

An exposure system according to an aspect of the present disclosure includes a laser apparatus emitting a pulse laser beam, an illumination optical system guiding the pulse laser beam to a reticle, a reticle stage moving the reticle, and a processor controlling emission of the pulse laser beam and movement of the reticle. The exposure system performs scanning exposure of a semiconductor substrate by irradiating the reticle with the pulse laser beam. The reticle has first and second regions. The processor instructs the laser apparatus about, based on proximity effect characteristics corresponding to the first and second regions, a value of a control parameter of the pulse laser beam corresponding to each region so that the laser apparatus emits the pulse laser beam with which a difference of the proximity effect characteristic of each region from a reference proximity effect characteristic is in an allowable range.

An electrodeless laser-driven light source includes a laser that generates a CW sustaining light. A pump laser generates pump light. A Q-switched laser crystal receives the pump light generated by the pump laser and generates pulsed laser light at an output in response to the generated pump light. A first optical element projects the pulsed laser light along a first axis to a breakdown region in a gas-filled bulb comprising an ionizing gas. A second optical element projects the CW sustaining light along a second axis to a CW plasma region in the gas-filled bulb comprising the ionizing gas. A detector detects plasma light generated by a CW plasma and generates a detection signal at an output. A controller generates control signals that control the pump light to the Q-switched laser crystal so as to extinguish the pulsed laser light within a time delay after the detection signal exceeds a threshold level.

A kind of all-solid-state high-power slab laser based on phonon band-edge emission, which is comprised of a pumping source, a focusing system, a resonant cavity and a self-frequency-doubling crystal; the said self-frequency-doubling crystal is a Yb-doped RECOB crystal cut into slab shape along the direction of the crystal's maximum effective nonlinear coefficient of its non-principal plane; by changing the cutting direction of the crystal, the phase matching of different wavelengths is realized, thus realizing laser output at the band of 560-600 nm; the said pumping source is a diode laser matrix with a wavelength of 880 nm-980 nm; the input cavity mirror and the output cavity mirror are coated with films to obtain laser output at the band of 560-600 nm; the two large faces of the said self-frequency-doubling crystal is cooled by heat sink and located between the input cavity mirror and the output cavity mirror.

A broadband optical amplifier for operation in the 2 μm visible wavelength band is based upon a single-clad Tm-doped fiber amplifier (TDFA). A compact pump source uses a combination of low-power laser diode with a fiber laser to provide a multi-watt pump beam without needing to include thermal management and/or pump wavelength stability components. The broadband optical amplifier is therefore able to be relatively compact device with fiber coupled output powers of >0.5 W CW, high small signal gain, low noise figure, and large OSNR, important for use as a versatile wideband preamplifier or power booster amplifier.

A broadband optical amplifier for operation in the 2 μm visible wavelength band is based upon a single-clad Ho-doped fiber amplifier (HDFA). A compact pump source uses a combination of discrete laser diode with a fiber laser (which may be a dual-stage fiber laser) to create a pump output beam at a wavelength associated with creating gain in the presence of Ho ions (an exemplary pump wavelength being 1940 nm). The broadband optical amplifier may take the form of a single stage amplifier or a multi-stage amplifier, and may utilize a co-propagating pump and/or a counter-propagating pump arrangement.

A multi-stage thulium-doped (Tm-doped) fiber amplifiers (TDFA) is based on the use of single-clad Tm-doped optical fiber and includes a wavelength conditioning element to compensate for the nonuniform spectral response of the initial stage(s) prior to providing power boosting in the output stage. The wavelength conditioning element, which may comprise a gain shaping filter, exhibits a wavelength-dependent response that flattens the gain profile and output power distribution of the amplified signal prior to reaching the output stage of the multi-stage TDFA. The inclusion of the wavelength conditioning element allows the operating bandwidth of the amplifier to be extended so as to encompass a large portion of the eye-safe 2 μm wavelength region.

An amplified hollow-core fiber (HCF) optical transmission system for low latency communications. The optical transmission system comprises a low-latency amplified HCF cable. The low-latency amplified HCF cable comprises multiple HCF segments (or HCF spans). Between consecutive HCF segments, the system comprises low-latency remote optically pumped amplifiers (ROPAs). Each ROPA comprises a gain fiber, a wavelength division multiplexing (WDM) coupler, and an optical isolator. Preferably, the ROPAs are integrated into the HCF cable. Each ROPA is pumped by a remote optical pump source, which provides pump light to the gain fiber. The gain fiber receives an optical transmission signal from the HCF. The WDM coupler combines the pump light with the optical transmission signal, thereby allowing the gain fiber to amplify the optical transmission signal to an amplified transmission signal. The amplified signal is transmitted to another HCF segment through the optical isolator.

A fiber laser apparatus includes: an amplification optical fiber that amplifies a laser beam; one or more pumping light sources that generate pumping light that is supplied to the amplification optical fiber; an output optical fiber including a first core that allows the laser beam amplified by the amplification optical fiber to propagate therethrough, and a first cladding having a refractive index lower than a refractive index of the first core and surrounding a circumference of the first core; a delivery fiber including a second core optically coupled to the first core of the output optical fiber, and a second cladding having a refractive index lower than a refractive index of the second core and surrounding a circumference of the second core; and a first housing unit that houses the amplification optical fiber and the output optical fiber therein.

An optical transmission device includes a first wavelength multiplexer, a second wavelength multiplexer, a wavelength converter and a third wavelength multiplexer. The first wavelength multiplexer multiplexes optical signals in a first wavelength band to generate first wavelength multiplexed light. The second wavelength multiplexer multiplexes optical signals in the first wavelength band to generate second wavelength multiplexed light in a first polarization. The wavelength converter converts a wavelength of the second wavelength multiplexed light from the first wavelength band into a second wavelength band by a cross phase modulation among the second wavelength multiplexed light, first pump light in a second polarization and second pump light in the second polarization. The second polarization is orthogonal to the first polarization. The third wavelength multiplexer multiplexes the second wavelength multiplexed light whose wavelength has been converted by the wavelength converter and the first wavelength multiplexed light.