Compact, robust, and spectrally pure diode-laser system with a filtered output and a tunable copy for absolute referencing
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We report on a design of a compact laser system composed of an extended-cavity diode laser with high passive stability and a pre-filter Fabry–Perot cavity. The laser is frequency-stabilized relative to the cavity using a serrodyne technique with a correction bandwidth of ≥6 MHz and a dynamic range of ≥700 MHz. The free-running laser system has a power spectral density (PSD) ≤100 Hz2/Hz centered mainly in the acoustic frequency range. A highly tunable, 0.5–1.3 GHz copy of the spectrally pure output beam is provided, which can be used for further stabilization of the laser system to an ultra-stable reference. We demonstrate a simple one-channel lock to such a reference that brings down the PSD to the sub-Hz level. The tuning, frequency stabilization, and sideband imprinting are achieved by a minimum number of key elements comprising a fibered electro-optic modulator, acousto-optic modulator, and a nonlinear transmission line. The system is easy to operate, scalable, and highly applicable to atomic/molecular experiments demanding high spectral purity, long-term stability, and robustness.
KeywordsCorner Frequency Acoustic Noise Optical Feedback Direct Digital Synthesizer Reference Cavity
We thank J. Berquist for providing the ULE cavity, J. Danzl for helping with the design of the PID circuit, and K. Aikawa for useful suggestions on the manuscript. We acknowledge generous support by R. Grimm. The work is supported by the European Research Council (ERC) under Project No. 278417.
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