Parity-Time Symmetric Laser and Absorber

Abstract

Lasers and anti-lasers (time-reversed counterpart of lasers) are critical for the generation and absorption of coherent light beams. Here we experimentally demonstrate on-chip switchable lasing and anti-lasing in a single photonic cavity using the concept of parity-time symmetry. This opens the door for extreme light control towards the ultimate limit of modulation depth.