Note: Laser frequency shifting by using two novel triple-pass acousto-optic modulator configurations

Abstract

We report the design of two novel triple-pass acousto-optic modulator systems. These designs are extensions of the well known acousto-optic modulator (AOM) double-pass configuration, which eliminates the angle dependence of the diffracted beam with respect to the modulation frequency. In a triple-pass system, however, the frequency dependence of the angle does not disappear but the frequency shift is larger, spanning 3 times the AOM central frequency. In some applications, such as optically pumped Cesium-beam frequency standards, the frequencies of the two laser beams remain fixed and a triple-pass optical system can be used to reduce to one the number of lasers used in such atomic clocks. The two triple-pass configurations use either a retro-reflecting mirror, or a right angle prism to pass for third time the laser beam through the AOM, obtaining diffraction efficiencies of about 27% and 44%, respectively.

Opto-Electronics Review

“…A useful solution is an AOM in a double-pass configuration which doubles the frequency offset, widens the tuning bandwidth and, at the same time, significantly reduces beam pointing fluctuations [83]. Also, higher multi-pass schemes, odd [84] or even [85], high diffraction orders [86] or combinations thereof [87] can be employed to expand the range of frequency shifts.…”