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A relatively simple efficient electrooptically Q-switched Er:Cr:YSGG laser oscillator-amplifier system in a line has been demonstrated. A Glan-Taylor prism and a cubic LiNbO3 crystal are used as the polarizer and modulator, respectively. Using the line scheme, one can adjust the system elements easily and achieve a good Q-switched-to-free-running pulse energy ratio of 75% and an energy amplification coefficient of 1.8. As short as 80 ns of the leading edge of a stable single pulse and 132 ns in FWHM with an energy of 24.5 mJ are generated. We also investigate the effects of the pump energy and the delay time on the postlasing, the stable single-pulse operation, the prelasing, the laser buildup time, and the Q-switched pulse width. The laser system demonstrated can be used for the effective ablation of soft and hard tissues.

Two types of electro-optically Q-switched Er:Cr:YSGG lasers with different polarizing mechanisms have been operated. For the one Q-switching and polarizing are realized with only a LiNbO3 crystal with both ends cut at Brewster's angle and for the other they are achieved by a cubic LiNbO3 crystal and a Glan-Taylor prism, respectively. The two schemes are compared with regard to both the mechanical and laser Q-switched properties.

We propose a novel scheme for light amplification and gain equalization by quantum interference. We find that the laser amplification can be observed at three specific probe frequencies in a four-level system. Furthermore, we show that three gain peaks can be combined into one to obtain gain equalization.

A five-level system to control the wavelength of the in-line amplifier by the quantum interference is proposed. It is found that the gains of the first and the second probe can be adjusted by changing the coherent field and the incoherent pumping. The new scheme may find its application in optical switch and optical communications.

Inhomogeneously broadened doped solids supporting electromagnetically induced transparency are viable materials where optically tunable photonic band gaps may be observed and results are shown for Pr:YSO and nitrogen-vacancy color center materials. Such crystals, when coherently driven by a strong pump beam in a suitably designed standing wave configuration, exhibit a tunable stop-band with rather different values of the reflectivity. The different propagating behavior is investigated and characterized for a weak probe across the gap region of the two materials.

The modulation of parameters of single-mode and multimode lasers has frequently been used to generate giant “Q-switched” pulses. This modulation is particularly effective when it is matched to the damped relaxation oscillation frequency (or when it is a slightly lower value to match the longer periodicity of the giant pulses) [1]. The nonlinear response of a CO2 laser to modulation was used by Arecchi and coworkers in one of the earliest studies of optical chaos [2]. Further experiments have been performed with cavity loss, gain, and cavity length modulation in CO2 lasers [3–6], primarily for the study of nonlinear dynamics (period doublings, chaos, crises, etc.).

We investigate both the four-level model and the six-temperature model to describe the dynamical processes of a simple mechanical Q-switched CO2 laser that is realized by a fast chopper. The Q-switched process and the effect of the dynamic parameters on the output intensity of the Q-switched CO2 laser are reported using the two models. Theoretical comparisons between the two models on the effect of dynamical parameters, and the experimental results are presented. Both the models are well consistent with the experimental one for the main output laser pulse.

Employing a coated right-angled sapphire prism as the OPO cavity mirror, AgGaS2 type-I singly resonant optical parametric oscillator was demonstrated experimentally, which was pumped by a ns 1.064 μm Nd:YAG laser. Continuously tunable 2.35 to 5.27 μm radiation without changing cavity mirrors and maximum output energy 0.58 mJ per pulse are recorded.