Fig. 1: Experimental arrangement and QCL device structure and characteristics.
From: High-speed modulation of a terahertz quantum cascade laser by coherent acoustic phonon pulses
a Experimental arrangement for measuring the optical and electronic perturbation of a THz QCL by laser-generated picosecond acoustic pulses. The sample is mounted on the cold finger of an optical cryostat at an operating temperature of 15 K. b Schematic diagram of the QCL device structure showing the transmitted (solid red line) and reflected (dashed red line) strain pulses. c L‒I‒V characteristics of the QCL in the absence of acoustic pulses, measured at a temperature of ~10 K and driven with 50-µs pulses at a 1-kHz repetition rate. Labels correspond to the different QCL biasing conditions used in experiments: (V1 = 4.13 V, VA = 5.02 V, V2 = 5.49 V and V3 = 5.58 V). d Simplified QCL band structure showing two periods of the structure with labelled injection level (IL-|2〉), upper laser level (ULL-|11′〉) and lower lasing level (LLL). Source data for c and d are provided in ref. 50.
