Integrated tunable phase shifter based on energy-conserved phase amplification and its application for RF-OAM generation

Abstract

Photonics-assisted microwave phase shifter is one of the essential components in communications. Phase amplification is a promising technology which efficiently enables compact photonics-assisted microwave phase shifter. Based on vector sum, the phase shift can be translated from amplitude attenuation to phase amplification. This issues an additional optical energy consumption and even more the highly dependent signal to noise ratio of phase-shifted microwave signal. In this paper, we propose an energy-conserved phase amplification concept to address this issue. Furthermore, based on this concept, we demonstrate a microwave photonic phase shift system with an integrated chip incorporating an arrayed waveguide gratings (AWG) structure. A multichannel continuous 360° phase shift over a frequency range of 12 GHz–20 GHz can be achieved by changing the optical carrier wavelength. Taking advantages of phase modulator and AWG structure, a reliable and efficient phase shifter for beam steering and orbital angular momentum (OAM) generation system can be realized without any other active device. The simulation results of OAM purity test show that better OAM beams can be obtained with the proposed phase shifter. This integration method has great potential in RF OAM generation and multiplexing system to improve the signal quality and reduce the system complexity.