China University of Science and Technology Successfully Developed All-optically Controlled Non-reciprocal Multifunction Photonic Devices

[ China Instruments Network Instrument Development ] Guo Guangcan, a member of the Chinese Academy of Sciences and a professor at the University of Science and Technology of China, has made new progress in the research of non-reciprocal photonic devices. The team's Dong Chunhua research team for the first time used the non-reciprocal nature of the cavity light in the whispering gallery mode microcavity to implement an all-optically controlled non-reciprocal multifunction photonic device, and for the first time realized an integrated optical directional amplifier. The results were published online on May 4th in the international journal Nature Communications.

Cavity photodynamics based circulator and directional amplifier schematic

Light has bidirectional transmission reciprocity in common media, and breaking this reciprocity, that is, achieving non-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. The optical circulator allows light to be transmitted in a “ring” manner, which can be used for light source protection and precise measurement. This function can also realize bidirectional processing of signals in classical or quantum computing or communication, which is beneficial to increase channel capacity and reduce power consumption. Directional amplifiers have also been demonstrated to be significant in quantum computation based on superconducting loops. The most common optical non-reciprocal devices mainly use the Faraday effect of magneto-optic crystals, but they face challenges in device integration. Difficulties include the mismatch between magneto-optical materials and traditional semiconductor materials, and the need to enhance the magnetic field in the optical frequency range. Magneto-optical materials have a very high transmission loss. Therefore, all-optically controlled on-chip optical circulators, isolators, and directional amplifiers have always been the focus of research.

In 2016, the research team experimentally validated the non-reciprocal nature of cavity light in a whispering gallery mode microcavity [Nature Photonics 10, 657-661 (2016)]. On this basis, the research team used a system combining a single optical microcavity and dual waveguides to implement a versatile photonic device, including a narrow-band filter, a non-reciprocal four-port optical circulator and an directional amplifier. The function mode can be switched arbitrarily by changing the control light. For the circulator, the signal light incident from the port 1 exits from the port 2, the signal light incident from the port 2 exits the port 3, and so on, constituting a 1-2-3-4-1 circular path when only Focusing on ports 1 and 2, it is also an efficient opto-isolator; for directional amplifiers, signal light incident from port 1 is amplified and exits from port 2, but signal light incident from port 2 exits from port 3, not Will exit from port 1, so in the direction of 1-2 has directional amplification. The device is simple in structure and universal in principle. It can even realize optical circulators with single-photon level, and can be extended to any photodynamic system with traveling wave mode, including microwave superconducting devices and integrated acoustic devices.

Associate researcher Shen Zhen, postdoctoral Zhang Yanlei, and doctoral candidate Chen Yuanwei were the co-first authors of the paper, and Dong Chunhua, Zou Changling, and Sun Fangwen were the authors of the correspondence. The above research has been supported by the Ministry of Science and Technology's key R&D program, the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the Quantum Information and Quantum Technology Collaborative Innovation Center.

(Original title: China University of Science and Technology has successfully developed all-optically controlled non-reciprocal multi-function photonic devices)