Abstract
An overview is given about experiments with a new method for Q-switching lasers at a constant pulse repetition frequency. It uses inside the laser resonator a Single Crystal Photo-Elastic Modulator (SCPEM). This consists of one piezo-electric crystal electrically excited on a mechanical resonance frequency. In resonance mechanical stresses are induced that lead via the photo-elastic effect to a strongly modulated birefringence. Polarized light going through such an oscillating crystal will experience a significant modulation of its polarization and of transmission through a polarizer. Suitable materials should not be optically active, as it is for example the case for SiO 2 , and should allow the excitation of a longitudinal oscillation with an electric field perpendicular to the travelling direction of the light. Crystals of the group 3m, like LiTaO 3 and LiNbO 3 , proved to be ideally suited for SCPEMS for the NIR- and VIS-region. For the infrared GaAs can be used. We demonstrated SCPEM-Q-switching for a Nd:YAG-fiber, a Nd:YVO4-slab- and a Nd:YAG-rod-laser with typical pulse repetition rates of 100-200kHz, pulse enhancement factors of ~100 and pulse durations ~1/100 of the period time. Typically the average power during pulsed operation is nearly the same as the cw-power, when the modulator is switched off. The most stable results were achieved up to now with the Nd:YVO4-slab-laser at 10W average power, 1.1 kW peak power, 127 kHz pulse repetition rate, and 70ns pulse durations.
Highlights
Q-switching is a common technology to produce laser pulses
We introduce here Single Crystal Photo-Elastic Modulators (SCPEM) that combine features of both technologies, namely first the change of polarization in case of electro-optics, and second the use of the photo-elastic effect as in acousto-optics
With a proper choice of parameters stable pulsed operation is possible with high efficiencies, little loss in average power, peak power 100 times higher the average power, pulse repetition rates 100300 kHz, and pulse durations down to 25ns
Summary
Q-switching is a common technology to produce laser pulses. It is based on a fast optical switch in the laser resonator blocking laser light while pumping energy is stored in the gain medium. We introduce here Single Crystal Photo-Elastic Modulators (SCPEM) that combine features of both technologies, namely first the change of polarization in case of electro-optics, and second the use of the photo-elastic effect as in acousto-optics. These resonant devices allow running lasers on a constant pulse repetition frequency determined by the crystal size and excited eigenmode
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
