Low phase noise microwave generation with fiber-based femtosecond lasers and applications

When a femtosecond laser is servoed onto an ultra-stable cw laser, its repetition rate acquire an extreme spectral purity. By photodetecting the pulses, we are able to generate ultra-low phase noise microwave signals and use it for cutting edge metrology experiments. We present our past and present work to generate microwave signal with very low degradation from the limit imposed by the reference oscillator, using a highly reliable fiber-based system. The latest developments involve employing an intra-cavity electro-optic modulator (for increased servo bandwidth), reduced relative intensity noise of the laser, and studies of the photodetector amplitude to-phase conversion.