Experimental studies of modal gain, absorption and dispersion of nanostructured semiconductor lasers emitting in the near-infrared wavelength regime

Semiconductor photonics based optical frequency combs generated by monolithic mode-locked semiconductor lasers emitting in the near-infrared wavelength region are ideal sources for time critical applications including optical data communication. Ultra-short optical pulses can be emitted but due to group delay dispersion inside the laser cavity, the pulses are in most cases not Fourier-limited and it is even possible to have mode-locking operation without any pulse laser output [Bardella et al, Opt. Expr. 25 (2017), 26234]. To obtain ultra-short pulses, a precise knowledge of the group delay dispersion and the modal gain of the laser material is critically required. We study experimentally the spectrally-resolved modal gain, absorption and dispersion properties of nanostructured semiconductor lasers at different emission wavelengths.