On‐chip broadband nonreciprocal light storage
Moritz Merklein, Birgit Stiller, Khu Vu, Pan Ma, Steve Madden, Benjamin J. Eggleton
Abstract
Abstract Breaking the symmetry between forward‐ and backward‐propagating optical modes is of fundamental scientific interest and enables crucial functionalities, such as isolators, circulators, and duplex communication systems. Although there has been progress in achieving optical isolation on‐chip, integrated broadband nonreciprocal signal processing functionalities that enable transmitting and receiving via the same low‐loss planar waveguide, without altering the frequency or mode of the signal, remain elusive. Here, we demonstrate a nonreciprocal delay scheme based on the unidirectional transfer of optical data pulses to acoustic waves in a chip‐based integration platform. We experimentally demonstrate that this scheme is not impacted by simultaneously counterpropagating optical signals. Furthermore, we achieve a bandwidth more than an order of magnitude broader than the intrinsic optoacoustic linewidth, linear operation for a wide range of signal powers, and importantly, show that this scheme is wavelength preserving and avoids complicated multimode structures.