image: A parity-time symmetric optoelectronic oscillator in which two optoelectronic loops have identical geometry but with one having a gain coefficient and the other a loss coefficient, identical in magnitude, is implemented. Once the gain/loss coefficient is greater than the coupling coefficient, the PT symmetry condition is broken, and the mode that has the highest gain is selected. view more
Credit: ©Science China Press
This review is completed by Prof. Jianping Yao (Microwave Photonics Research Laboratory, School of Electrical Engineering and Computer Science, University of Ottawa) and Prof. Jose Capmany (ITEAM Research Institute, Universitat Politècnica de Valencia).
A comprehensive review of microwave photonics techniques with their implementation based on both discrete components and photonic integrated circuits (PICs) was performed.
First, the basic concepts of microwave photonics including the general architecture of a microwave photonics link and its performance measures including the link gain, noise figure (NF), and spurious free dynamic range (SFDR) were provided.
Then, high-frequency and low-phase-noise microwave signal generation based on photonics technology was discussed, including optical injection locking, optical phase lock loop, external modulation, and optoelectronic oscillation, among which parity-time symmetry in an optoelectronic oscillator was discussed in more detail. The main advantage of using parity-time symmetry in an optoelectronic oscillator is the high-performance mode selection capability that enables stable single-mode oscillation while maintaining a high Q factor to ensure ultra-low phase noise generation. Then, techniques to implement microwave photonic filters based on incoherent and coherent detection, arbitrary waveform generation based on direct space-time mapping, spectral shaping and wavelength-to-time mapping, and temporal pulse shaping were discussed. Broadband phased array beamforming based on photonics was also discussed.
Finally, integrated microwave photonics (IMWP) was reviewed. First, the materials systems that can be employed for the implementation of microwave photonic subsystems and systems including indium phosphide (InP), silicon on insulator (SOI), silicon nitride (Si3N4) and lithium niobate on insulator (LOI), were reviewed. Then, recent progress in application-specific photonic integrated circuits, where a particular circuit configuration to optimally perform a particular microwave photonics functionality, was discussed. General
purpose programmable microwave photonic signal processors that are capable of performing all the main microwave signal generation and processing functionalities by suitable software programming were also reviewed.
See the article:
Microwave photonics
https://doi.org/10.1007/s11432-021-3524-0
Journal
Science China Information Sciences