Real-Time RF Multi-Dimensional Signal Switching Using Polarization-Dependent Optical Mixing

Qidi Liu,Mable P Fok

doi:10.1109/jphot.2020.2977847

Abstract

Real-time switching of RF signal properties, including phase, frequency, and amplitude, is essential for emerging high-speed RF systems to improve security, signal fidelity, and enhance data capacity. While it is easy to switch the amplitude of an RF signal at GHz speed, unfortunately, it is extremely challenging to perform phase or frequency switching of an RF signal with a fast switching time in the picosecond range. In this paper, a real-time RF signal switching technique is proposed and demonstrated based on polarization dependent four-wave mixing in a highly-nonlinear optical fiber. Due to the amplitude, phase, and frequency transparent property of four-wave mixing, the proposed scheme is capable of manipulating multidimensional RF signal of over tens of GHz frequency, and achieve frequency hopping and phase switching of a GHz RF signal. The switching time is not limited by the proposed temporal switching technique; instead, it is solely depending on the rise/fall time of the control signal itself. Furthermore, the generation of frequency hopping signal with a switching time of 50 ps, as well as simultaneously frequency and phase switching of a GHz RF signal have been experimentally demonstrated based on the proposed RF signal switching scheme.

Highlights

Due to the increasing demands of information security and high data fidelity in countermeasurement for military applications, as well as high data capacity requirement in emerging RF communications, there is a critical need for real-time switching of high-speed RF signal [1], [2]
Ultrafast frequency switching for frequency hopping (FH) signal generation is of particular interest due to its unique advantages such as immunity to inter-symbol interference and anti-jamming capability that are essential in modern RF systems [3], [4]
A clean frequency hopping between 5 GHz and 8 GHz is observed with uniform amplitude profile

Summary

Introduction

Due to the increasing demands of information security and high data fidelity in countermeasurement for military applications, as well as high data capacity requirement in emerging RF communications, there is a critical need for real-time switching of high-speed RF signal [1], [2]. The use of microwave photonic filters [13]–[18], including stimulated Brillouin scattering based [13] and comb filter based [14] techniques for generating fast-switching frequency hopping signal can achieve hopping speed of hundreds of picoseconds. We propose and demonstrate a novel microwave photonic technique to achieve real-time switching of various RF signal properties, including frequency and phase switching, as well as amplitude modulation over a wide operation frequency range. Fiber optics based FWM has been widely investigated for wavelength conversion, signal multicasting, supercontinuum generation, signal regeneration, logic operation, frequency comb generation, optical phase conjugation as well as fiber-optic parametric amplification [24]–[26] In most of these applications, the polarization sensitive property in FWM is a disadvantage that would degrade the performance of the systems. The proposed technique works well for microwave signal mixing of both amplitude and phase modulations without the need of hybrid electrical devices for single sideband modulation [21], [22] or complicated off-line phase compensation [27]

Experimental Details

Results

Conclusions