Lasing spectral blue shifts of fluorescent saturable absorbing dye in microdroplets

Abstract

We report blue shifts of emission spectra of microdroplet lasers containing fluorescent saturable absorbing dye as compared with those of conventional dye lasers. The results cannot be simply explained by matching the lasing peaks to the minima of threshold condition without taking into account cavity enhancement. We find that the microdroplet lasers have quality factors of 10(4) with a 3X cavity enhancement and their lasing peaks at fixed concentration are independent of the incident pump power.