All-fiber widely tunable ultrafast laser source for multimodal imaging in nonlinear microscopy.

Abstract

In this Letter, we present an all-fiber, easy-to-use, wavelength-tunable, ultrafast laser, based on soliton self-frequency shifting in an Er-doped polarization-maintaining very large mode area fiber. The system is tunable over 370nm, starting at 1620nm, with an average power of up to 1.5W that emits 120fs short laser pulses directly out of the fusion-spliced fiber without using bulky pulse compression optics. The output is subsequently frequency doubled to a wavelength range covering 810nm up to almost 1000nm with more than 500mW average power and 120fs pulse width. Having a polarization extinction ratio better than 40dB and a M2 of 1.1, the fully computer-controlled laser system presents a robust and compact laser source. These parameters make the laser perfectly suited for multimodal imaging in nonlinear microscopy.