Robust tunable external cavity diode laser using a volume holographic grating for rubidium atom cooling

Abstract

We present a robust external cavity diode laser, developed for atom trapping experiments, demonstrating a high level of stability. The novel design includes a zerodur tube surrounding the laser cavity for maximal thermal and mechanical cavity stability, a volume holographic grating (VHG) with narrow frequency bandwidth to provide optical feedback, and a micromachined silicon flexure to hold the VHG and allow for laser frequency sweeping. Using a silicon flexure allowed for temperature control of the VHG as well as a reduction of the overall size of the laser system. The results demonstrate a frequency sweeping range of 12 GHz enabled by PZT actuators, a mode-hop-free tuning range of 6 GHz with a non-AR-coated diode, a frequency tuning range of 33 GHz by changing diode current and applied PZT voltage, and a linewidth of <1 MHz. The laser frequency drift was measured to be <1.5 MHz/min, superior to that of many off-the-shelf external cavity diode lasers.