Fig. 5
From: Fast Swept-Wavelength, Low Threshold-Current, Continuous-Wave External Cavity Quantum Cascade Laser
a The measured EC-QCL wavelength with the galvanometer voltage of 20 mV and the tuning frequency of 0.02 Hz. The mode hop is about 0.5 cm−1. b The measured EC-QCL wavelength tuning with a sawtooth wave modulation (0.02 Hz, 40 mA), which can compensate for the 0.5 cm−1 mode hop. c The measured EC-QCL wavelength with both galvanometer tuning and sawtooth wave modulation