Scientists develop new optical switches with a 350-fold increase in speed

      Currently, ordinary electronic switches operate at 4 GHz, and scientists at the University of Twente in the Netherlands and the French Institute of Nanoscience and Cryogenic Engineering have developed a semiconductor planar microcavity switch that achieves a repetition rate of 1.4 THz. The rate has increased by 350 times, and the related results are published in Opt. Lett. 38, 374. The researchers constructed cavities in the gallium arsenide and aluminum arsenide layers and measured their resonant frequencies using 1284.1 nm of probe light. In the experiment, the team used two optical parametric amplifiers pumped by a near-infrared sapphire laser to inject the probe and trigger beams into the microcavity. The trigger beam produces an electric Kerr effect that changes the refractive index of the cavity material on a sub-picosecond time scale. The researchers extended the wavelength of the trigger beam to 2400 nm to reduce the two-photon absorption in the cavity. It is estimated that the cavity absorbs only one in a million of incident light. According to the author, the cavity storage time is approximately 300 fs, which determines the basic "rate limit" of the switching rate. This phenomenon does not depend on the geometry of the microcavity. In addition to ultra-fast on-chip photonic modulation, this new type of switch may be applied to basic research in cavity quantum electrodynamics, and it is possible to greatly increase the operating speed of future communication systems and even quantum computers.