Femtosecond Laser Cavity Dispersion Measurement Using Soliton Properties

Abstract

Near-zero second-order and nonnegligible third-order cavity dispersion have been measured using the soliton properties of pulses generated in a CPM laser.

We present in this paper two experimental measurements of the intracavity dispersion of a colliding pulse mode-locked (CPM) dye laser. This parameter is of crucial importance for this kind of laser and, until now, has never been experimentally measured. First, we will show that using soliton properties of the pulses one can obtain a good approximation of the second-order dispersion. Next we will show that the third-order dispersion is not negligible in our CPM laser and that, indeed, it is the factor preventing shorter pulses from being obtained.

All these experiments were conducted with a classical CPM laser using rhodamine 6G and DODCI dyes. All the mirrors were single stack coated for 100% reflectivity at normal incidence at 620 nm. With freshly prepared dyes, pulses as short as 31 fs (assuming a sech² profile) are obtained.