Passive negative feedback in mode-locked solid-state lasers.
Passive negative feedback by an intracavity GaAs platelet in actively/passively mode-locked solid-state lasers is reexamined, and the role of both single- and two-photon absorption in determining the features of the pulses and the pulse train is explored and compared with the experimental results. The time–bandwidth product is shown to acquire in the steady-state part of the train a value close to the minimum allowed by the uncertainty relation.
Lithium triborate picosecond optical parametric oscillator
Abstract We report on the first operation of a picosecond optical parametric oscillator (OPO) based on a lithium triborate (LBO) nonlinear crystal. A singly resonant, non-collinear OPO configuration was used, and the LBO was pumped synchronously by the third harmonic of a passive negative feedback mode-locked Nd:YAG laser, obtaining a conversion efficiency into the idler wave (@ 900 nm) of up to 10% and an internal overall efficiency of up to 26%.
Effects of finite probe intensity on degenerate frequency mixing in saturable amplifiers (A)
Abstract Phase conjugation by degenerate frequency mixing (DFM) in saturable amplifiers, including the effects of pump depletion, a non-zero incident probe wave intensity and saturated gain of all waves in the nonlinear medium, is analyzed numerically. Plane wave DFM reflectivities greater than unity are predicted, even in the presence of pump depletion, for sufficiently large amplifier gains. At a given level of incident probe-wave intensity the DFM reflectivity approaches its weak probe-wave value at sufficiently large incident pump intensities, but deviates from these values at lower pump intensities. Conditions are established under which the DFM reflectivity is effectively independent of the incident probe-wave intensity even when the incident pump intensity is smaller than that of the incident probe wave. Under these conditions the system holds the potential for faithful conjugation using pump waves that are considerably weaker than the probe waves being conjugated. The results also predict that under certain conditions, the intensity of the backward-generated wave can be larger than either the incident probe wave or the incident pump wave.