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Indexed by:Journal Papers

Date of Publication:2019-11-01

Journal:JOURNAL OF LIGHTWAVE TECHNOLOGY

Included Journals:SCIE

Volume:37

Issue:21

Page Number:5370-5379

ISSN No.:0733-8724

Key Words:RF signals; Signal detection; Optical sensors; Optical filters; Gain; Amplitude modulation; Optical reflection; Equivalent phase modulation; low power RF signal detection; optoelectronic oscillator; phase-shifted fiber Bragg grating

Abstract:A novel photonic method for low power radio-frequency (RF) signal detection by a tunable optoelectronic oscillator (OEO) with high gain based on equivalent phase modulation (EPM) is proposed and experimentally demonstrated. A dual-parallel Mach-Zehnder modulator is utilized to generate the EPM signal with a controllable optical carrier to sideband ratio, by which the gain to the RF signal by the OEO loop can be enhanced. A phase-shifted fiber Bragg grating (PS-FBG) with a narrow-band notch in its reflection band implements the phase modulation to intensity modulation conversion by removing one sideband of the EPM signal. The gain and noise performance of the detection system are theoretically analyzed and simulated. In the experiment, the maximum gain of 10.4 dB is obtained at 8 GHz, and the detection sensitivity for RF signals from 2 to 18 GHz are within the range of 87.7 to 84.3 dBm by using the developed detection system. Compared to normal phase modulation based scheme, the EPM-based system offers 9.1 dB higher gain. Utility of the proposed approach for detecting modulated RF signal is also investigated and an optimization scheme is discussed.