Investigation of carrier to envelope phase and repetition rate: Fingerprints of mode-locked laser cavities

We use mode locked lasers in a non-conventional way, as a sensor to perform intracavity measurements. To understand this new technique of intracavity phase interferometry (IPI), one should take a detailed look at the characteristics of the frequency comb and its sensitivity to its parent cavity. The laser cavity provides a means to perform phase interferometry while outside the cavity one can only observe amplitude intereference. Many physical quantities such as nonlinear index, Earth rotation, magnetic field, Fresnel drag, etc are converted to phase. IPI is performed by designing laser cavities in which two pulses circulate independently, generating two pulse trains that can have a phase difference that will be converted to frequency. We also explore repetition rate spectroscopy in Rb by tailoring a laser wavelength, power and bandwidth. Coherent population trapping is observed when the laser repetition rate matches submultiples of hyperfine splitting. © 2009 IOP Publishing Ltd.