The phase link between signal, idler, and pump waves in a parametric interaction allows generation of an idler pulse with a phase independent of that of the input pulse. We suggest the use of a white-light seeded optical parametric amplifier as a self-stabilized source of few-cycle pulses, in which the phase of the electric field is exactly reproduced in each laser shot.

Angular dispersion of pump frequencies is shown to be an efficient mechanism for bandwidth enhancement in a noncollinear optical parametric amplifier. We demonstrate the generation of a continuous, simultaneously phase-matched 250-THz parametrically amplified spectrum. The resultant visible–near-IR signal-wave pulses were compressed to a 4-fs duration by a micromachined flexible mirror. Feedback for an iterative computer-controlled dispersion compensation algorithm is based on pulse characterization by second-harmonic generation frequency-resolved optical gating.

We demonstrate an optical parametric chirped-pulse amplifier producing infrared $20\mathrm{fs}$ (3-optical-cycle) pulses with a stable carrier-envelope phase. The amplifier is seeded with self-phase-stabilized pulses obtained by optical rectification of the output of an ultrabroadband Ti:sapphire oscillator. Energies of $\sim 80\mu \mathrm{J}$ with a well-suppressed background of parametric superfluorescence and up to $400\mu \mathrm{J}$ with a superfluorescence background are obtained from a two-stage parametric amplifier based on periodically poled $\mathrm{Li}\mathrm{Nb}{\mathrm{O}}_3$ and $\mathrm{Li}\mathrm{Ta}{\mathrm{O}}_3$ crystals. The parametric amplifier is pumped by an optically synchronized $1\mathrm{kHz}$, $30\mathrm{ps}$, $1053\mathrm{nm}$ Nd:YLF amplifier seeded by the same Ti:sapphire oscillator.

Generation of sub-two-cycle, microjoule pulses in the mid-infrared region is demonstrated. Fundamental and second-harmonic pulses of $25\mathrm{fs}$ Ti:sapphire amplifier output were focused into the air to produce extremely broadband mid-infrared pulses by four-wave difference-frequency generation through the filamentation. The full width at half-maximum of the spectral bandwidth reaches one octave $(2.5–5.5\mathrm{\mu }\mathrm{m})$, which is sufficiently broad for sub-single-cycle pulse generation. The pulse width was estimated to be $13\mathrm{fs}$, without any compressors, by cross-correlation frequency resolved optical gating. The output energy of more than a few microjoule is sufficient for spectroscopy.

Generation of deep-ultraviolet femtosecond pulses by four-wave mixing through filamentation in neon gas was demonstrated. Fundamental $\left(\omega \right)$ and second-harmonic $\left(2\omega \right)$ pulses of $25\mathrm{fs}$ Ti:sapphire amplifier output were focused into neon gas, and $20\mathrm{\mu }\mathrm{J}$ pulses with the center wavelength of $260\mathrm{nm}$ were produced by a four-wave mixing process, $2\omega +2\omega -\omega \to 3\omega$ through an $\sim 15\mathrm{cm}$ filament. Additionally, pulses with an energy of $2\mathrm{\mu }\mathrm{J}$ at $200\mathrm{nm}$ were generated, probably by a cascaded process, $3\omega +2\omega -\omega \to 4\omega$. The $260\mathrm{nm}$ pulses were compressed by a grating-based compressor and characterized by a dispersion-free transient grating frequency-resolved optical gating. The estimated pulse width was $12\mathrm{fs}$.

We demonstrate a Kerr-lens mode-locked Ti:sapphire oscillator that generates 130-nJ, 26-fs and 220-nJ, 30-fs pulses at a repetition rate of 11 MHz. The generation of stable broadband, high-energy pulses from an extended-cavity oscillator is achieved by the use of chirped multilayer mirrors to produce a small net positive dispersion over a broad spectral range. The resultant chirped picosecond pulses are compressed by a dispersive delay line that is external to the laser cavity. The demonstrated peak powers, in excess of 5 MW, are to our knowledge the highest ever achieved from a cw-pumped laser and are expected to be scalable to tens of megawatts by an increase in the pump power and (or) a decrease in the repetition rate. The demonstrated source permits micromachining of any materials under relaxed focusing conditions.