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A: Fachverband Atomphysik

A 40: Ultracold Atoms II (with Q)

A 40.3: Vortrag

Freitag, 10. März 2017, 15:00–15:15, P 104

Optimization of modulation transfer spectroscopy on the rubidium D2 line — •Tilman Preuschoff, Patrick van Beek, Florian Ehmann, Malte Schlosser, and Gerhard Birkl — Institut für Angewandte Physik, Technische Universität Darmstadt, Schlossgartenstraße 7, 64289 Darmstadt, Germany

Highly stable laser sources with narrow linewidths are of great importance for experiments in the field of atom physics. Frequency-stabilized external-cavity diode lasers are a cost efficient and compact realization of suitable sources. Sub-Doppler spectroscopy techniques provide high resolution atomic references. Among them, the modulation transfer spectroscopy (MTS) scheme is significant due to the non-linear four-wave-mixing transfer process which offers a particularly high accuracy and signal bandwidth.
We present recent experimental and theoretical investigations of the MTS technique on the ⁸⁵Rb D2 line in an AOM-based setup. The obtained line shape is in good agreement with the theoretical description. Numerical simulations show that an optimal combination of signal amplitude and slope at the reference frequency is achieved in the regime of high modulation indices and frequencies. Within the experimentally available parameter regime this optimum is accessible. We demonstrate a frequency stabilization providing an effective linewidth below 200 kHz and a long-term stability better than 100 kHz in 15 h. The MTS scheme is compared to the frequency modulation spectroscopy scheme implemented in a similar optical setup based on inexpensive DDS signal generation and standard lock-in techniques.