Fig. 3: Comparison in the time and frequency domains of free-running (black), fundamental (red) and harmonic (orange) modelocking. | Light: Science & Applications

Fig. 3: Comparison in the time and frequency domains of free-running (black), fundamental (red) and harmonic (orange) modelocking.

From: Ultrafast response of harmonic modelocked THz lasers

Fig. 3: Comparison in the time and frequency domains of free-running (black), fundamental (red) and harmonic (orange) modelocking.

a Time traces for a free-running QCL showing quasi-CW behaviour, fundamental modelocking with 1 pulse per round-trip and second harmonic modelocking with two pulses per round-trip. b Spectrum showing a limited number of modes for the free-running QCLs, with an enhanced number of modes for the fundamental and second harmonic modelocked QCLs with a mode separation equal to the round-trip and twice the round-trip frequency, respectively

Back to article page