We describe the stabilization of the beatnote of an Er,Yb:glass dual-frequency laser at 1.5 µm with and without an external microwave reference. In the first case, a classical optical phase-locked loop (OPLL) is used, and absolute phase noise levels as low as -117 dBrad2/Hz at 10 kHz from the carrier are reported. In the second case one or two fiber-optic delay lines are used to lock the frequency of the beatnote. Absolute phase noise levels as low as -107 dBrad2/Hz at 10 kHz from the carrier are measured, fairly independant of the beatnote frequency varying from 2 to 6 GHz. An analysis of the phase noise level limitation is presented in the linear servo-loop theory framework. The expected phase noise level calculated from the measurement of the different noise sources fits well with the predictions.
© 2008 IEEE
Grégoire Pillet, Loïc Morvan, Marc Brunel, Fabien Bretenaker, Daniel Dolfi, Marc Vallet, Jean-Pierre Huignard, and Albert Le Floch, "Dual-Frequency Laser at 1.5 µm for Optical Distribution and Generation of High-Purity Microwave Signals," J. Lightwave Technol. 26, 2764-2773 (2008)