Optically Controlled Non-Reciprocal Photonic Device

The schematic of the optomechanical circulator and directional amplifier. (Source: Z. Shen)

The Micro­cavity Research Group in the Key Labora­tory of Quantum Infor­mation at the Univer­sity of Science and Techno­logy of China USTC in Hefei have perfected a 4-port all-optically controlled non-reciprocal multi­functional photonic device based on a magnetic-field-free opto­mechanical resonator is demon­strated for the first time.

Light has bidirec­tional trans­mission reci­procity in common dielectric material. Breaking this reciprocity in the direction of light trans­mission is of great signi­ficance in classical and quantum information processing. Optical circu­lators, isolators, direc­tional amplifiers, etc. are typical non-reci­procal devices. Yet the most common optical non-reci­procal devices are based on the Faraday effects using magneto-optical materials, which are difficult to inte­grate on-chip. Therefore, in recent years, interest has increased in realizing on-chip all-optical non-reci­procal devices.

In 2016, DONG Chunhua’s group experi­mentally demon­strated the opto­mechanically induced non-reci­procity in a whispering gallery mode micro­cavity. On this basis, the group use a single cavity coupled with dual wave­guides to implement a 4-part versatile photonic device, including the functions of narrow-band filter, four-port optical circulator and direc­tional amplifier. The function mode can be switched arbi­trarily by changing the control light.

For the circu­lator, the signal light incident from the ports 1, 2, 3 and 4, exits from the ports 2, 3, 4 and 1, respec­tively, consti­tuting a 1-2-3-4-1 circular path. When only focusing on ports 1 and 2, it is also an efficient optical isolator; for direc­tional amplifiers, signal light incident from port 1 is ampli­fied and exits from port 2, not the other way around. Thus in the direction of 1-2 has direc­tional amplifi­cation. The demon­strated device can even realize optical circu­lators with single-photon level and can be genera­lized to micro­wave and acoustic circuits. (Source: USTC)

Reference: Z. Shen et al.: Reconfigurable optomechanical circulator and directional amplifier, Nat. Commun. 91797 (2018); DOI: 10.1038/s41467-018-04187-8

Link: Key Laboratory of Quantum Information, Chinese Academy of Sciences, University of Science and Technology of China, Hefei, China

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