Abstract

Ultra-broadband laser frequency combs operating at multi-gigahertz repetition rate are important for applications in frequency metrology, as well as time-resolved and frequency-domain spectroscopy. A compact Ti:Sapphire laser (depicted in Fig. 1(a)) is a promising candidate for implementing such a frequency comb. Recently a 10 GHz self-referenced Ti:Sapphire was shown to provide an ultra-broadband optical spectrum after external broadening in a microstructure fiber [1]. This provided an octave spectrum for detecting the carrier-envelope offset frequency [1,2]. However, the use of nonlinear fiber with high average power introduces challenges for long-term stability. Thus, it is interesting to consider the possibility of directly generating octave spectra [3,4] at repetition rates that could ultimately approach 10 GHz. To our knowledge, the highest repetition rate obtained with an octave-spanning Ti:Sapphire ring laser, is 2.166 GHz [4]. Here we report the achievement of a 4.3 GHz octave-spanning laser frequency comb.

© 2013 IEEE