In this work, the sensitivity to external optical feedback of two different InAs/GaAs QD Fabry-Perot (FP) lasers is investigated under long cavity regime. The first, which has a 1.5 mm-long cavity, emits on the GS while the second one, which is 1 mm long, radiates solely on the ES transition. The results indicate that for the same bias level, the ES laser presents a larger sensitivity to external feedback, the critical level being under 1% versus above 9% for the GS laser. In particular, the ES laser exhibits a route to chaos such that the first destabilization occurs for a lower feedback strength than for the GS laser.
Frequency conversion using highly non-degenerate four-wave mixing is reported in InAs/GaAs quantum-dot Fabry- Perot lasers. In order to compress the spontaneous emission noise, the laser is optically injection-locked. Under proper injection conditions, the beating between the injected light frequency and the cavity resonant frequency dominates the dynamic behavior and enhances a carrier modulation resonance at frequencies higher than the relaxation oscillation frequency. Conversion efficiencies as high as -12 dB associated to a large optical signal-to-noise ratio of 36 dB are reported. The conversion bandwidth is extended up to 2.1 THz for down-conversion (resp. 3.2 THz for up-conversion) with a quasi-symmetrical response between up- and down-converted signals.
Non-degenerate four-wave mixing effects are investigated in an injection-locked InAs/InP nanostructure Fabry-Perot laser. Locking a longitudinal mode at various wavelengths within the gain spectrum and using the locked mode as the pump for the wave mixing shows different levels of asymmetry between up- and down-conversion. Experiments reveal that the normalized conversion efficiency is less asymmetric when the pump is locked at wavelengths below that of the gain peak. The values of nonlinear conversion efficiencies are maintained above -60 dB for pump-probe frequency detunings up to 3.5 THz. The role of the linewidth enhancement factor on the asymmetry is discussed and the value of the nonlinear susceptibility is compared to similar InAs/InP nanostructure semiconductor optical amplifiers. From an end-user viewpoint, data transmission experiments have also confirmed the possibility to propagate up-converted signals over 100 km at a 5 Gb/s bit rate under an OOK modulation format.