Coherent, Inc.

Michael Hertwig

Norman Hodgson

Sergei V Govorkov

H Yang Pang

Luis A Spinelli

Andrea Caprara

Dmitri Simanovski

Michele Wayne Winz

Keith M Murdoch

Nick Hartmann

An ultrashort-pulse compressor includes (a) one or more bulk-optics intersecting a propagation path of an ultrashort-pulsed laser beam multiple times to spectrally broaden a pulse of the laser beam during each of multiple passes through the bulk-optic(s), (b) one or more dispersive optics for compressing a duration of the pulse after each of the multiple passes, and (c) a plurality of focusing elements for focusing the laser beam between the multiple passes. Propagation distances between the bulk-optic(s) and the focusing elements are detuned from imaging such that a spot size of the laser beam, at the bulk-optic(s), is greater at each successive one of the multiple passes. As the laser beam propagates through this compressor, each laser pulse is alternatingly spectral broadened and temporally compressed. The increasing spot size of the laser, for each pass, helps prevent optical damage, run-away self-focusing, and other undesirable outcomes.

Spectrally broadening ultrashort-pulse compressor

A thermally actuated adaptive optic includes a base, a reflector, and a plurality of actuators coupled therebetween. The reflector has a light-receiving front surface, and a back surface facing the base. Each actuator includes a bracket rigidly bonded to the reflector at a perimeter of the reflector, and an inner rod and an outer rod. Each rod is rigidly connected between the bracket and the base, with the inner rod being closer to a center of the reflector. The length of each rod is temperature dependent. In another adaptive optic, the rods are instead bonded directly to the reflector. This adaptive optic may be modified to implement an integrally formed, thermally actuated support. The disclosed adaptive optics are suitable for use in laser systems, allow for significant cost savings over piezoelectric devices, provide a reflective area free of surface-figure perturbations caused by the actuator-interfaces, and are relatively simple to manufacture.

Thermally actuated adaptive optics

A mirror is used to form a beam of laser-radiation having a uniform intensity distribution from a beam of laser-radiation having a non-uniform intensity distribution. The mirror has a reflective surface that has a compound shape, which is two inclined surfaces joined by a rounded apex. The compound-mirror is achromatic and can form a uniform intensity distribution from a polychromatic beam of laser-radiation. The uniform intensity distribution may be an isotropic distribution or a flat-top distribution in a plane. The non-uniform intensity distribution may be a Gaussian distribution from a laser source.

Reflective laser line-beam generator

Plane-polarized laser-radiation from a laser-source is converted to circularly polarized radiation by a quarter-wave plate. The circularly polarized radiation is input into a hollow-core fiber for transport to a point of use. The transported radiation is converted back to plane-polarized radiation by another quarter-wave plate between the fiber and the point of use.

Transport of polarized laser-radiation using a hollow-core fiber

An optical amplifier includes a solid state gain-element. The gain-element is pumped by pump-radiation from a diode-laser bar. The diode-laser radiation is delivered from the diode-laser bar to the gain-element entirely via a tapered light-guide which guides the radiation only in a fast-axis direction of the diode laser bar. The tapering of the light-guide reduces fast-axis divergence of the pump-radiation by about a factor of ten. The pump-radiation is delivered to the gain-element as a line of radiation homogenized in the fast-axis direction.

Optical pumping apparatus for slab lasers and amplifiers

A laser includes a Ti:sapphire gain-medium in the form of a thin-disk. The thin-disk gain-medium is optically pumped by pump-radiation pulses having a wavelength in the green region of the electromagnetic spectrum. The pump-radiation pulses have a duration less than twice the excited-state lifetime of the gain-medium.

Transition-metal-doped thin-disk laser

A master oscillator power-amplifier stages includes multiple stages of fiber-amplification with a final power amplifier stage in the form of a multi-pass amplifier. With a thin-disk gain medium in one example the thin-disk amplifier includes a common optical arrangement for providing multiple incidences of radiation to be amplified and multiple incidences of a pump-radiation beam on the thin-disk gain medium.

Hybrid fiber-MOPA

Multi-pass optical imaging apparatus includes a concave mirror in combination with two retro-reflecting mirror pairs and at least one reflective surface. The mirror, the retro-reflecting mirror pairs and the reflecting surface are arranged such that a light-ray input into the apparatus parallel to and spaced apart from the optical axis of the concave mirror and incident on the concave mirror is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences on the gain-medium being from a different direction. If the input ray is plane-polarized, the arrangement provides that the polarization orientation of the ray on each incidence on the gain-medium is in the same orientation.

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San Ramon, CA, United States of America

Michael Hertwig