Precise passive synchronization of dissipative soliton resonance lasers via cascaded cross-phase- and cross-absorption-modulation for mid-infrared mode-locked pulse generation

• First use of cascaded cross-phase/absorption modulation in mode-locked fiber lasers. • Achieved 13.5 cm cavity optical path and 1.87 kHz pulse frequency mismatch sync. • Record pulse repetition frequency sync dynamic range in DSR lasers demonstrated. • Generated mode-locked mid-IR pulses at 2 MHz with 3.60 × 10 -13 fractional instability. We present the first demonstration of utilizing cascaded cross-phase and cross-absorption modulation effects for synchronizing the pulse parameters of two mode-locked fiber lasers operating in the dissipative soliton resonance regime. By utilizing the cross-absorption modulation effect we achieve a significant improvement in pulse repetition frequency synchronization dynamic range (13.5 cm cavity optical path mismatch, or 1.87 kHz pulse repetition frequency mismatch) while simultaneously achieving passive pulse duration synchronization through injection of synchronization pulses into the gain fiber of one of the Slave lasers. This approach leads to a record pulse repetition frequency synchronization dynamic range. Subsequently, the synchronized DSR lasers at 1.06 µm and 1.56 µm are employed in a nonlinear difference frequency generation stage to generate mode-locked mid-infrared pulses with a pulse repetition rate of ∼ 2 MHz and an exceptional fractional instability of 3.60 × 10 -13 , measured for a 1000 s integration time.