Abstract

High efficiency diffraction modulation of light by strain-optic effect of piezo-electrically induced standing acoustic waves was presented at the annual OSA meeting in Orlando last year.¹ A more detailed paper on piezo-electrically induced strain-optic (PESO) diffraction modulation has been submitted to a journal on short communications. One of the reviewers has objected to our preference of PESO- modulator to the traditional standing-wave acousto-optic ones. One of the objections relates to the disadvantages of extremely low bandwidth and connecting temperature instabilities by use of high overtones, in consideration of the PESO modulator as a practical device. Meanwhile, application of a LiNbO₃ PESO-modulator for mode-locking a Kr⁺ laser pumped Nd glass laser was carried out.² The laser uses a commercial LiNbO₃-fused silica acousto-optic (AO) mode-locker. The shortest pulse width of 7 ps could be achieved. Replacing it by the PESO diffraction modulator, we achieved pulses as short as 3.8 ps. The system worked with high stability and insertion of the modulator could be accomplished without problems arising from the usage of the commercial Bragg modulator. Recently, Irvine replaced a high quality AO-modulator for our PESO in a YiLF laser. He has achieved 17ps pulses, about one third of the 50ps pulse width obtained with the commercial modulator. In consideration of the self-stabilization mechanism observed in the experiments, a simple-model to interpret the physical processes ensuring a high degree of stabilization has been developed.

© 1990 Optical Society of America