Low phase noise microwave signals can be generated by photo-detecting the pulse train of an optical frequency comb locked to a high spectral purity continuous-wave optical reference. Amplitude-to-phase noise conversion is, however, a well-known limitation to this technique. Great care is usually required to overcome this constraint due to its strong dependence on the impinging optical power. Here we demonstrate the combined use of “magic point” operating conditions of photodetectors, pulse repetition rate multipliers, and coherent addition of microwave signals to realize a microwave extraction device largely immune to amplitude-to-phase conversion effects over a large range of impinging optical powers.
© 2014 Optical Society of America
Lasers and Laser Optics
Original Manuscript: December 19, 2013
Revised Manuscript: January 15, 2014
Manuscript Accepted: January 17, 2014
Published: February 21, 2014
Wei Zhang, Signe Seidelin, Abhay Joshi, Shubo Datta, Giorgio Santarelli, and Yann Le Coq, "Dual photo-detector system for low phase noise microwave generation with femtosecond lasers," Opt. Lett. 39, 1204-1207 (2014)