Publications by authors named "W T Lotshaw"

We report on the generation of mid-infrared Kerr frequency combs in high-finesse CaF2 and MgF2 whispering-gallery-mode resonators pumped with continuous-wave room-temperature quantum cascade lasers. The combs were centered at 4.5 μm, the longest wavelength to date.

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We observed spectral broadening caused by self-phase modulation in 400- and 600-microm core diameter fibers using amplified, Q-switched, Nd:YAG laser pulses with peak powers to 150 kW. The degree of spectral broadening was not dependent linearly on the fiber length as in single-mode fibers because of the more complicated modal evolution in highly multimode fiber. Furthermore, even slight stress near the input end of the fiber reduced the observed broadening.

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A synchronously pumped, hybridly mode-locked, antiresonant-ring dye laser that is insensitive to cavity-length variations of up to 15 microm is described. At a cavity length that is 70-80 microm shorter than the synchronous cavity length this laser generates stable pulses as short as 55 fsec, with a pulse width of 65 fsec being typical (assuming a sech(2) pulse shape). No evidence for colliding-pulse mode-locking effects is observed.

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