Stabilized High Pulse Energy Passively Mode-Locked Monolithic and External Cavity Tapered Lasers for Space Applications

European Space Agency (ESA) considers picosecond mode-locked semi-conductor laser technology as a promising candidate for space applications in precision optical metrology systems. However, very challenging performance requirements should be met by such laser without additional amplification stages. In order to address this challenge, we realized two types of mode-locked edge emitting lasers operating at 990 nm wavelength. In particular, we demonstrate a very-long (13.5 mm) monolithic multi-section tapered laser reaching 201 pJ mode-locked pulses at low repetition frequency of 2.89 GHz with the pulse width that can be compressed down to 2.4 ps. We also report on a multi-section inverse bow-tie external cavity laser producing mode-locked pulses of 70 pJ energy and 6 ps width (0.73 fs after compressor) at 1.65 GHz pulse repetition frequency (PRF). The laser operates in an 80-mm-long external cavity. The PRFs of the two lasers can be continuously tuned over 9.8 and 9.1 MHz ranges, respectively. Active stabilization with a phase locking loop actuating on the driving current has allowed us to reach PRF relative stabilities of 1.15·10
^-10
and 2.9·10
^-10
on 1 s intervals for the two lasers. These performances fulfill the requirements of ESA for inter-satellite long distance measurements.