Victor Yanovsky

Generation of 25-fs pulses from a self-mode-locked Cr:forsterite laser with optimized group-delay dispersion.

25-fs pulses with energies of 4 nJ are generated from a self-mode-locked Cr:forsterite laser with optimized cavity dispersion. The duration of the shortest pulses is limited by the gain bandwidth of Cr:forsterite. Using a model based on a solitonlike pulse formation, we infer a value of 2 × 10−16 cm2/W for the nonlinear refractive index of forsterite at 1.3 μm.

Self-mode-locked Cr:forsterite laser

We have demonstrated self-sustaining operation of a mode-locked chromium-doped forsterite laser in which short-pulse formation is entirely due to the nonlinearity of the laser crystal. Stable pulse trains are generated for intracavity pulse energies from 35 to 120 nJ. Pulses less than 100 fs in duration are obtained over the range of 1.23–1.28 μm, with a maximum average output power of 700 mW for 9 W of pump power.

Frequency doubling of 100-fs pulses with 50% efficiency by use of a resonant enhancement cavity

The use of a resonant cavity for efficient second-harmonic generation with 100-fs pulses is demonstrated. With 2-nJ pulses from a mode-locked Cr:forsterite laser, 53% conversion efficiency to the second harmonic at 625 nm is achieved while ~100-fs duration is maintained. This is an order-of-magnitude improvement over the conversion efficiency obtained directly with the laser output.

Nonlinear propagation of high-power, sub-100-fs pulses near the zero-dispersion wavelength of an optical fiber

The propagation of high-peak-power (>10-kW) sub-100-fs pulses near the zero-dispersion wavelength of an optical fiber was studied experimentally. Four-photon mixing and stimulated Raman scattering were observed for fiber lengths greater than 2 m. With pulses as short as 25 fs, four-photon mixing dominates, resulting in efficient conversion of the input pulse spectrum into two coherent spectral bands. This can be used to extend the useful wavelength range of femtosecond lasers in the infrared.

Kerr-lens mode-locked diode-pumped Cr:LiSGAF laser.

We have demonstrated stable and self-sustaining Kerr-lens mode locking of a Cr:LiSGAF laser pumped by AlGaInP laser diodes. A hard aperture near one end of the laser provides the necessary amplitude modulation. This allsolid- state system generates transform-limited 100-fs pulses, tunable from 810 to 860 nm. The average power at 830 nm is 35 mW, with fluctuations of much less than 1%. The thermal properties of Cr:LiSGAF will permit scaling of these results to higher power.

Femtosecond diode-pumped Cr:LiSGAF lasers

The design and performance of diode-pumped Cr:LiSrGaAlF/sub 6/ lasers mode-locked by Kerr-lens mode-locking and a solid-state saturable absorber are described. The different regimes of operation of the laser mode-locked by the saturable absorber are discussed. Both lasers generate 100-fs pulses with average powers of 40 mW and low fluctuations.

Self-modelocked Cr:forsterite laser with optimized group-delay dispersion

Self-modelocked operation of a cw-pumped Cr:forsterite laser and the generation of pulses as short as 25 fs from a self-modelocked Cr:forsterite laser with optimized cavity dispersion are demonstrated. The pulse duration is limited by the gain bandwidth of Cr:forsterite and corresponds to only 6 optical cycles. From measurements of the performance of the laser the dispersion and nonlinearity of forsterite are obtained. Finally, a regime of modelocked operation which has not been observed previously is reported along with a tentative explanation in terms of gain saturation and gain dispersion.