Spectral phase control and temporal superresolution toward the single-cycle pulse.

The concept of temporal superresolution is applied to optical few-cycle laser pulses for the first time to our knowledge. Pulse durations of as little as to 3.7 fs, well below the Fourier limit, are achieved by pulse shaping of an octave-spanning Ti:sapphire oscillator spectrum. Our prism-based pulse shaper also enables us to generate a manifold of well-controlled pulse sequences that are important for coherent control applications on a femtosecond time scale.

All-optical active mode locking with a nonlinear semiconductor modulator.

All-optical active mode locking of a picosecond Nd:YVO(4) laser is demonstrated by use of an intracavity semiconductor nonlinear Fabry-Perot mirror. The reflectivity of the Fabry-Perot mirror is modulated by optical carrier injection. Depending on the carrier recombination time, the width of the Nd:YVO(4) laser pulses varies from 6 to 20 ps, as is typical for passively mode-locked Nd:YVO(4) lasers.

Nonlinear optics with phase-controlled pulses in the sub-two-cycle regime.

Nonlinear optical effects due to the phase between carrier and envelope are observed with 5 fs pulses from a Kerr-lens mode-locked Ti:sapphire laser. These sub-two-cycle pulses with octave spanning spectra are the shortest pulses ever generated directly from a laser oscillator. Detection of the carrier-envelope phase slip is made possible by simply focusing the short pulses directly from the oscillator into a BBO crystal. As a further example of nonlinear optics with such short pulses, the interference between second- and third-harmonic components is also demonstrated.

Generation of 5-fs pulses and octave-spanning spectra directly from a Ti:sapphire laser.

Spectra extending from 600 to 1200 nm have been generated from a Kerr-lens mode-locked Ti:sapphire laser producing 5-fs pulses. Specially designed double-chirped mirror pairs provide broadband controlled dispersion, and a second intracavity focus in a glass plate provides additional spectral broadening. These spectra are to our knowledge the broadest ever generated directly from a laser oscillator.