A modular, compact and widely
tunable laser system for the efficient generation of
high peak and high average power ultrashort pulses.
Modularity is ensured by the implementation of interchangeable
amplifier components.
System compactness is ensured by employing efficient
fiber amplifiers, directly or indirectly pumped by
diode lasers. Peak
power handling capability of the
fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-
phase modulation and
gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple
fiber delay lines or chirped
fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers. The phase of the pulses in the dispersive
delay line is controlled to quartic order by the use of fibers with varying amounts of
waveguide dispersion or by controlling the
chirp of the
fiber gratings. After amplification, the dispersively stretched pulses can be re-compressed to nearly their bandwidth limit by the implementation of another set of dispersive
delay lines. To ensure a wide tunability of the whole
system, Raman-shifting of the compact sources of ultrashort pulses in conjunction with frequency-conversion in
nonlinear optical crystals can be implemented, or an Anti-Stokes fiber in conjunction with fiber amplifiers and Raman-shifters are used. A particularly compact implementation of the whole
system uses fiber oscillators in conjunction with fiber amplifiers. Additionally, long, distributed, positive dispersion optical amplifiers are used to improve transmission characteristics of an
optical communication system. Finally, an
optical communication system utilizes a Raman
amplifier fiber pumped by a
train of Raman-shifted,
wavelength-tunable pump pulses, to thereby amplify an optical
signal which counterpropogates within the Raman
amplifier fiber with respect to the pump pulses.