Fig. 3: Polariton-based amplitude modulation up to 1.5 GHz at 300 K.
From: Fast amplitude modulation up to 1.5 GHz of mid-IR free-space beams at room-temperature
a Sketch of the experimental setup to measure the modulator bandwidth. The sample S is pumped with a commercial tunable mid-infrared QC laser focused with a ZnSe (L2) lens; the back reflected beam is collected through the beam-splitter BS, and sent to the detectors D0 (fast MCT Vigo detector with nominal bandwidth 1 KHz–837 MHz) and D1 (general purpose 50 MHz-bandwidth MCT detector, LN-cooled). A signal generator (RF or LF depending on the measurement) is used to apply the electrical bias to the sample. The electrical signal from the detector is then sent to specific analyzers: a spectrum analyzer (SA) to collect the beat-note spectrum or a lock-in. PM power meter, WL white light, P polarizer, λ/2 half-wave plate, Vis-Cam visible camera, MIR-Cam MIR camera. b Normalized beat-note spectra obtained when the sample is fed with 10 dBm/DC@−989 mV with modulation frequencies 100 MHz, 500 MHz, 1 GHz, and 1.5 GHz from top left. The measurements are performed at room-temperature, and the measured sample is the small one (surface is 2 × 104 μm2, p = 4.1 μm). The QC laser frequency is 1010 cm−1. Two curves are shown for each panel: laser-on (solid blue line) and laser-off (solid red line). The modulator performs up to at least 1.5 GHz.
