| 摘要 |
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 R1, a convex spherically curved mirror [CXM] with a radius of curvature R2, 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.
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