Broadband Semiconductor Mirrors with a Small Relaxation Time for Passive Mode-Locking of NIR Lasers

Two types of mirror structures with saturable absorption are under consideration: monolithic mirrors grown from semiconductor materials and mirrors with a dielectric reflector, with quantum well containing semiconductor structures transferred to the dielectric. Both types of mirrors manifest high reflectivity in the NIR range of the spectrum: the table width is about 100 nm for semiconductor reflectors and more than 200 nm for dielectric reflectors. It is shown that a maximum depth of absorption modulation from 1 to 40% is possible. The recovery time of the saturable absorber (2 ps) makes these mirrors significantly fit for using in lasers with a pulse repetition rate of 1 GHz.