Apparatus and method for femtosecond pulse compression based on selective attenuation of a portion of an input power spectrum

An apparatus for decreasing a temporal duration of an optical input pulse having an input power spectrum associated therewith, said apparatus operative on at least unchirped optical input pulses, said apparatus comprising:

• a zero-dispersion pulse shaper for receiving said optical input pulse and spectrally spreading said optical input pulse to produce a spectrally-spread pulse;
• a liquid crystal (LC) modulator array interposed within said zero-dispersion pulse shaper for receiving said spectrally-spread pulse;
• control circuitry, coupled to said LC modulator array, that selectively drives individual pixels of said modulator array to a finite gray-level, whereby said modulator array selectively attenuates a central portion of said power spectrum of said spectrally-spread pulse by a predetermined amount to produce a selectively-attenuated spectrally-spread pulse, said zero-dispersion pulse shaper focusing and recombining said selectively-attenuated spectrally-spread pulse to produce an output pulse having an output power spectrum;
• spectrum-measuring circuitry adapted to measure said output power spectrum, said control circuitry controlling said LC modulator array to alter said predetermined amount as a function of said output power spectrum, said output pulse further having a controllably decreased temporal duration, regardless of whether said input pulse is chirped.