Electromagnetically induced transparency and slow light with optomechanics

Abstract

A phenomenon known as electromagnetically induced transparency has been the subject of much research in atomic systems, as it makes it possible to slow down and stop light. Electromagnetically induced transparency and tunable optical delays have now been demonstrated in a nanoscale optomechanical device, fabricated simply by etching holes into a thin film of silicon. This achievement is a significant step towards the goal of fabricating an integrated quantum optomechanical memory. It is also relevant to classical signal-processing applications: at room temperature, the system can be used for optical buffering, amplification and altering of microwave-over-optical signals. In atomic systems, electromagnetically induced transparency (EIT) has been the subject of much experimental research, as it enables light to be slowed and stopped. This study demonstrates EIT and tunable optical delays in a nanoscale optomechanical device, fabricated by simply etching holes into a thin film of silicon. These results indicate significant progress towards an integrated quantum optomechanical memory, and are also relevant to classical signal processing applications: at room temperature, the system can be used for optical buffering, amplification and filtering of microwave-over-optical signals. Controlling the interaction between localized optical and mechanical excitations has recently become possible following advances in micro- and nanofabrication techniques1,2. So far, most experimental studies of optomechanics have focused on measurement and control of the mechanical subsystem through its interaction with optics, and have led to the experimental demonstration of dynamical back-action cooling and optical rigidity of the mechanical system1,3. Conversely, the optical response of these systems is also modified in the presence of mechanical interactions, leading to effects such as electromagnetically induced transparency4 (EIT) and parametric normal-mode splitting5. In atomic systems, studies6,7 of slow and stopped light (applicable to modern optical networks8 and future quantum networks9) have thrust EIT to the forefront of experimental study during the past two decades. Here we demonstrate EIT and tunable optical delays in a nanoscale optomechanical crystal, using the optomechanical nonlinearity to control the velocity of light by way of engineered photon–phonon interactions. Our device is fabricated by simply etching holes into a thin film of silicon. At low temperature (8.7 kelvin), we report an optically tunable delay of 50 nanoseconds with near-unity optical transparency, and superluminal light with a 1.4 microsecond signal advance. These results, while indicating significant progress towards an integrated quantum optomechanical memory10, are also relevant to classical signal processing applications. Measurements at room temperature in the analogous regime of electromagnetically induced absorption show the utility of these chip-scale optomechanical systems for optical buffering, amplification, and filtering of microwave-over-optical signals.