High power short pulse fiber laser

A method of producing compressed high power short laser pulses having an optical power of at least about 200 mW and a pulse duration of about 200 femtoseconds or less, said method comprising:

• substantially mode-locking longitudinal modes of a laser cavity to repetitively produce a laser pulse;
• amplifying said laser pulse using an amplifier downstream from the laser cavity;
• chirping said laser pulse thereby changing the optical frequency of said pulse over time;
• compressing said laser pulse using a compressor downstream from the laser cavity by propagating different optical frequency components of said laser pulse differently to produce a compressed laser pulse having a shortened temporal duration;
• and
• selectively attenuating the amplitude of said laser pulse prior to said amplifying of said laser pulse using an attenuator downstream from the laser cavity to further shorten said duration of said compressed laser pulse,
• wherein said laser pulse is attenuated by between about 1 to 20 dB.

A method of manufacturing a high power short pulse fiber laser, said method comprising:

• mode-locking a fiber-based oscillator that outputs optical pulses;
• optically coupling an amplifier to said fiber-based oscillator through a variable attenuator so as to feed said optical pulses from said fiber-based oscillator through said variable attenuator and to said amplifier;
• and
• adjusting said variable attenuator based on a measurement of said optical pulses to reduce the intensity of the optical pulses delivered to said amplifier and to shorten pulses at the output of the amplifier;
• wherein said amplifier and said variable attenuator are disposed downstream from said fiber-based oscillator, and
• wherein said optical pulses are attenuated by between about 1 to 20 dB.

An amplification system for outputting pulses having a pulse width, said amplification system comprising:

• a modelocked fiber oscillator producing an optical output comprising a plurality of optical pulses having a pulse width and a spectral power distribution having a bandwidth;
• an amplifier disposed external to the modelocked fiber oscillator and optically connected to said modelocked fiber oscillator for amplifying said optical pulses;
• a variable attenuator disposed between said modelocked fiber oscillator and said amplifier;
• and
• a spectral filter disposed external to the modelocked fiber oscillator and between said oscillator and said amplifier, said spectral filter configured to receive said optical output of said modelocked fiber oscillator prior to reaching said amplifier, said spectral filter having a spectral transmission with a band edge that overlaps said spectral power distribution of said optical output of said modelocked fiber oscillator to attenuate a portion of said spectral power distribution and thereby reduce the spectral bandwidth, the pulse width of said optical pulses coupled from said modelocked fiber oscillator to said amplifier thereby being reduced,
• wherein said spectral filter reduces the spectral bandwidth to less than about 12 nanometers,
• wherein said spectral filter has a spectral bandwidth of between about 5 and 12 nm;
• and
• wherein said variable attenuator comprises polarization selection optics.

A method of producing compressed optical pulses, said method comprising:

• substantially mode-locking longitudinal modes of a fiber resonant cavity so as to produce a train of modelocked optical output pulses having a corresponding spectral power distribution with a spectral bandwidth;
• amplifying said modelocked optical output pulses using an amplifier external to said fiber resonant cavity;
• compressing said modelocked optical output pulses using a compressor external to said fiber resonant cavity to produce compressed optical pulses;
• and
• reducing the spectral bandwidth of said spectral power distribution prior to amplifying using a spectral filter external to said fiber resonant cavity such that said compressed modelocked optical output pulses have a shorter duration,
• wherein said spectral bandwidth is reduced to less than about 12 nanometers, and
• wherein said spectral bandwidth is reduced by between about 5 to 12 nm.

A system for producing compressed high power short laser pulses having an optical power of at least about 200 mW and a pulse duration of about 200 femtoseconds or less, said system comprising:

• a mode locked oscillator to mode-lock longitudinal modes of a laser cavity to repetitively produce a laser pulse;
• at least one fiber amplifier amplifying said laser pulse, said at least one amplifier disposed downstream from the laser cavity;
• a pulse stretcher comprising a length of optical fiber or a chirped fiber Bragg grating, said stretcher chirping said laser pulse thereby changing the optical frequency of said optical pulse over time;
• a pulse compressor to compress said laser pulse by propagating different optical frequency components of said laser pulse differently to produce a compressed laser pulse having a shortened temporal duration, said compressor disposed downstream from the laser cavity;
• and
• an attenuator to selectively attenuate the amplitude of said laser pulse prior to said amplifying of said laser pulse, said attenuator disposed downstream from the laser cavity to further shorten said duration of said compressed laser pulse, and wherein said laser pulse is attenuated by between about 1 to 20 dB.