Parity-time symmetry in wavelength space within a single spatial resonator

Jiejun Zhang; Lingzhi Li; Guangying Wang; Xinhuan Feng; Bai-Ou Guan; Jianping Yao

doi:10.1038/s41467-020-16705-8

Parity-time symmetry in wavelength space within a single spatial resonator

Nat Commun. 2020 Jun 25;11(1):3217. doi: 10.1038/s41467-020-16705-8.

Authors

Jiejun Zhang¹, Lingzhi Li², Guangying Wang², Xinhuan Feng², Bai-Ou Guan², Jianping Yao^{3

4}

Affiliations

¹ Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 511443, China. zhangjiejun@jnu.edu.cn.
² Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 511443, China.
³ Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 511443, China. jpyao@uottawa.ca.
⁴ Microwave Photonics Research Laboratory, School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON, K1N 6N5, Canada. jpyao@uottawa.ca.

Abstract

We show a parity-time (PT) symmetric microwave photonic system in the optical wavelength space within a single spatial resonator, in which the gain and loss modes can perfectly overlay spatially but are distinguishable in the designated parameter space. To prove the concept, a PT-symmetric optoelectronic oscillator (OEO) in the optical wavelength space is implemented. The OEO has a single-loop architecture, with the microwave gain and loss modes carried by two optical wavelengths to form two mutually coupled wavelength-space resonators. The operation of PT symmetry in the OEO is verified by the generation of a 10-GHz microwave signal with a low phase noise of -129.3 dBc/Hz at 10-kHz offset frequency and small sidemodes of less than -66.22 dBc/Hz. Compared with a conventional spatial PT-symmetric system, a PT-symmetric system in the wavelength space features a much simpler configuration, better stability and greater resilience to environmental interferences.