Reduction of residual amplitude modulation to 1×10-6 for frequency-modulation and cavity-based laser stabilization

Author(s): W. Zhang, M. J. Martin, C. Benko, J.L. Hall, J. Ye, C. Hagemann, T. Legero, U. Sterr, F. Riehle, G. D. Cole, M. Aspelmeyer

Journal: Optics Letters

Volume: 9

Page(s): 1980-1983

Year: 2014

DOI Number: 10.1364/OL.39.001980

Link: Link to publication


Active control and cancellation of residual amplitude modulation (RAM) in phase modulation of an optical carrier is one of the key technologies for achieving the ultimate stability of a laser locked to an ultrastable optical cavity. Furthermore, such techniques are versatile tools in various frequency modulation-based spectroscopy applications. In this Letter we report a simple and robust approach to actively stabilize RAM in an optical phase modulation process. We employ a waveguide-based electro-optic modulator (EOM) to provide phase modulation and implement an active servo with both DC electric field and temperature feedback onto the EOM to cancel both the in-phase and quadrature components of the RAM. This technique allows RAM control on the parts-per-million level where RAM-induced frequency instability is comparable to or lower than the fundamental thermal noise limit of the best available optical cavities.

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