Clark-mxr, Inc.

Yang Pang

Edward F Gabl

David R Walker

Christopher T Cotton

William G Clark

An ultrashort optical pulse amplifier that incorporates a gain medium preferentially cooled along a crystalline axis for partially ameliorating the thermally induced distortions and losses created by cylindrically symmetric cooled designs. The ultrashort pulse amplifier can be pumped with higher pump powers without degradation of the output spatial mode structure and the overall efficiency of extraction of energy from the gain medium is improved. The gain medium preferably has a rectangular cross section and cooling means are provided in thermal contact with only selected opposing surfaces of the gain medium so that thermal gradients lie approximately along a crystalline axis to reduce thermally-induced birefringence.

Ultrashort optical pulse amplifiers incorporating a gain medium

A regenerative amplifier includes a resonant cavity having a gain medium and a spectral filter located in the cavity. A source is provided to pump the gain medium and thereby raise it to an excited state. Elements are also provided for creating laser seed pulses which are then injected into the resonant cavity, these elements preferably include in part a mode-locked oscillator having a wavelength substantially the same as that at which the gain medium can support amplification of the energy of the injected pulse. In a preferred embodiment the gain medium is Ti:Sapphire for both the amplifier and oscillator. Also, in the preferred embodiment the seed pulse from the oscillator is stretched in time by multiplicative factors sufficient to ensure that upon amplification, the seed pulse power density remains below the self-focusing threshold of the material through which the pulse is passed. The seed laser pulses are injected into the resonant cavity of the regenerative amplifier so as to provide multiple traversals of the resonant cavity and the gain medium therein, thereby amplifying the pulses. The pulse is recompressed back to some predetermined pulse width of interest to the user; for example, back to the temporal pulse width that is limited by the spectral bandwidth of the output pulse.

Regenerative amplifier incorporating a spectral filter within the

An apparatus for stretching or compressing an ultrashort pulse in time that is free of non-linear and spatial distortion (temporal or spatial frequency chirp) comprises a first diffraction grating G, a concave spherically curved mirror [CCM] with a radius of curvature R.sub.1, a convex spherically curved mirror [CXM] with a radius of curvature R.sub.2, and a flat reflector, [PM]. As a result of propagation of the ultrashort input pulse through this system, the output pulse is either stretched (or compressed) in time so that it now has a duration many times longer (or many times shorter) than its input pulse duration, is spatially uniform (i.e. has no spatial chirp,) and collimated. It can be separated from the input pulse by passage through a Faraday isolator. If the invention is to be configured as a stretcher, the stretched pulse can then be seeded into an amplifier stage, wherein it is amplified by many orders of magnitude, without placing the materials within the system at risk of damage due to self-focusing. Subsequently it is temporally compressed by a similar design or other designs known to those skilled in the art. It may also be recompressed by an identical optical design wherein the grating is repositioned relative to the concave mirror so as to recompress the pulse.

Optical system for stretching, compressing and amplifying ultrashort

A regenerative amplifier includes a resonant cavity having a gain medium and a spectral filter located in the cavity. A source is provided to pump the gain medium and thereby-raise it to an excited state. Elements are also provided for creating laser seed pulses which are then injected into the resonant cavity, these elements preferably include in part a mode-locked oscillator having a wavelength substantially the same as that at which the gain medium can support amplification of the energy of the injected pulse. In a preferred embodiment the gain medium is Ti:Sapphire for both the amplifier and oscillator. Also, in the preferred embodiment the seed pulse from the oscillator is stretched in time by multiplicative factors sufficient to ensure that upon amplification, the seed pulse power density remains below the self-focusing threshold of the material through which the pulse is passed. The seed laser pulses are injected into the resonant cavity of the regenerative amplifier so as to provide multiple traversals of the resonant cavity and the gain medium therein, thereby amplifying the pulses. The pulse is recompressed back to some predetermined pulse width of interest to the user; for example, back to the temporal pulse width that is limited by the spectral bandwidth of the output pulse.

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Ann Arbor, MI, United States of America

Yang Pang