Characterization of a 10 GHz harmonically mode-locked erbium fiber ring laser using SHG FROG

Summary form only given. Active, harmonic mode-locking of erbium fiber ring lasers (EFRLs) is an established technique for obtaining short pulses at GHz repetition rates. To date all reports on the characterization of such lasers have used techniques that provide incomplete information on the pulse shape and quality, e.g. autocorrelation with optical spectrum, streak camera etc. Whilst this is largely adequate, direct measurements of pulse amplitude and phase would be extremely useful, facilitating the optimization and detailed understanding of the operation of such lasers. Over the past few years frequency resolved optical gating (FROG) has become an established technique for fully characterizing ultrashort pulses. So far, it has been mainly used, and associated with, high peak-power pulsed laser sources of relatively low repetition rate. However, the power requirements and resolution are in fact fully commensurate with telecommunication grade fiber laser requirements. In the paper we report what is to the best of our knowledge the first FROG characterization of a high repetition rate picosecond pulse EFRL, characterizing in detail the intracavity pump power dependent pulse shaping.