Interaction of Modulated Optical Fields with Saturable Media and its Application to Laser Instability

David A. Holm, M. Sargent, Barbara A. Capron

Over the past three years we have developed a quantum theory of multiwave mixing designed to determine effects of quantum noise on laser and optical bistability instabilities, pump/probe saturation spectroscopy, AM and FM modulation spectroscopy, and phase conjugation. The theory treats a classical pump field and one or two quantum-mechanical sidemode fields interacting with one- or two-photon, two-level media. The theory1 produces a master equation for the reduced sidemode density operator able to describe all of the above phenomena in a uniform way closely related to the corresponding semiclassical theories. It has led to a number of significant predictions about the effects of spontaneous emission on laser spectroscopy and optical instabilities.

Е. В. Ивакин, V. G. Koptev, Alexander M. Lazaruk +2 more

E. Arimondo

Kevin L. Schehrer, Edward S. Fry

The time dependence of the frequency shift (δω) due to colliding-pulse phase modulation (CPPM) is computed, for collision of femtosecond optical pulses, both in nonresonant and in saturable media. In particular, thin material slabs (up to several pulse widths τ) are considered, and although the results are more generally applicable, special attention is given to a typical saturable-absorber jet in a colliding-pulse mode-locked laser. Results show that CPPM in nonresonant media causes noticeable effects on the chirp, both for thin slabs with L ≈ laser wavelength, where the coherence of the pulses leads to interference effects, and for thicker slabs with L ≈ cτ. Complications to CPPM by saturable media are discussed, and it is shown that the consequences of dispersion by the ground-state population, and finite phase-relaxation time, may be important for short, low-energy pulses. The results show, for parameters typical of contemporary colliding-pulse mode-locked lasers, what conditions are favorable for short, stable pulse formation in solitonlike pulse shaping. It is also shown that there are conditions for which the pulses produced would be spread by any sign of group-velocity dispersion.

Hermann Haken, H. Sauermann

Steve Stuut, Murray Sargent

The effects of Gaussian-beam averaging with various apertures are derived for three-wave mixing in nonlinear two-level media. The model studies the phase transition from plane-wave to pure Gaussian saturation. Applications to phase conjugation, beat-frequency spectroscopy, and laser–optical-bistability instability phenomena are considered. The Gaussian beams are seen to reduce or wash out dynamic Stark splittings observed for plane-wave saturation. For strong saturation, the side-mode gain/absorption coefficient versus detuning yields slightly larger gain for the homogeneously broadened laser instability but substantially curtailed gain for the corresponding absorptive optical-bistability instability.