Physorg January 22, 2018
There are several problems with using magnetically responsive materials to achieve the one-way flow of light in a photonic chip. Researchers at University of Illinois at Urbana-Champaign, produced a non-reciprocal modulator by means of indirect interband scattering. They broke the time-reversal symmetry using a two-dimensional acoustic pump that simultaneously provides a non-zero overlap integral for light–sound interaction and satisfies the necessary phase-matching. Their device is 200 by 100 microns in size, made of aluminum nitride. Sound waves, produced using tiny electrodes written directly onto the aluminum nitride, compel light within the device to travel only in one direction. The device has applications in photonic communication systems, gyroscopes, GPS systems, atomic timekeeping and data centers… read more. TECHNICAL ARTICLEÂ
An array of 100 x 200 micron optical isolators uses sound to produce one-way light propagation. Credit: Benjamin Sohn