Laser frequency shift up to 5 GHz with a high-efficiency 12-pass 350-MHz acousto-optic modulator

Abstract

We demonstrate a novel laser frequency shift scheme using a 12-pass 350-MHz acousto-optic modulator (AOM). This AOM system shows better performance compared to ordinary acousto-optic modulation schemes. The frequency of the incident laser beam is shifted by 4.2 GHz with the total diffraction efficiency as high as 11%, and the maximum frequency shift is 5 GHz. Combining the ±1st order diffraction, laser signals with up to 10 GHz frequency difference can be obtained, which fulfill most frequency shift requirements of laser cooling and coherent manipulation experiments with alkali metal atoms.

Composite acousto-optical modulation

“…2), interference of diffraction amplitudes leads to rapid switching of the output at twice the rf driving frequency ω S , which can be exploited for efficiently routing a pulse train with up to GHz repetition rate into multiple directions. We expect the composite technique to enable advanced AOM applications with both CW [14,15,26] and pulsed lasers [16-18, 27, 28]. We notice related schemes of composite-pulse-inspired error-resilient 2-mode optical control have been derived [29][30][31] in scenarios where a mode-truncation as in this work is not required.…”

“…However, the Pockels cells can hardly operate beyond a 10 MHz rate since it is difficult to generate the powerful high-voltage waveforms while managing the dissipation [12]. Unlike high-voltage requirements for EOM, low-voltage rf signals can transduce crystal sound waves in acousto-optical modulators (AOM) to control the optical output with accurately programmable Bragg diffraction [13][14][15]. In addition to enabling arbitrary pulse picking with unlimited duty cycle [16], an excellent example to illustrate AOM pulse modulation is to shift the phase of individual pulses so as to stabilize the carrier-envelop phase of a frequency comb [17][18][19].…”

1.6 GHz Frequency Scanning of a 482 nm Laser Stabilized Using Electromagnetically Induced Transparency

“…To reach GHz shifts using an AOM, a single pass is typically not sufficient. Therefore, configurations including 2-, 3-, 4-, 6-, and even 12-passes [15]- [19] have been implemented. When using an AOM, the frequency-shifted light is separated from the carrier (that is the zeroth order beam) via diffraction.…”