Optically Tunable Microwave Frequency Downconversion Based on an Optoelectronic Oscillator Employing a Phase-Shifted Fiber Bragg Grating

Abstract

We demonstrate an approach to achieve optically tunable microwave frequency downconversion based on an optoelectronic oscillator (OEO) incorporating a tunable microwave photonic filter. The wideband tunable local oscillation (LO) is generated in the OEO through simply tuning the frequency difference between the optical carrier and the reflection notch of a phase-shifted fiber Bragg grating (PS-FBG). The LO and the input radio-frequency (RF) signal are combined and added to the OEO loop by a single-phase modulator. Through transmitting one modulation sideband of the LO via the reflection notch of the PS-FBG and combining it with the optical carrier split from the laser source, the oscillation of the LO in the OEO is maintained. The reflected modulation sidebands of the LO and the RF signal from the PS-FBG are exported out of the OEO loop and enter a narrowband photodetector to achieve optically tunable microwave frequency downconversion. Our method is experimentally evaluated, in which optically tunable LOs in the frequency range 6-15 GHz are generated, and RF signals in the frequency range 7-16 GHz are successfully downconverted to intermediate frequency band around 1 GHz.

Photonic radiofrequency receiver utilizing a phase modulator and a tunable single sideband optoelectronic oscillator

“…However, the RF signal and LO are applied to one RF port, and the output isolation between RF and LO is low. In Reference , an optically tunable RF downconversion mixer based on an OEO incorporating a microwave photonic filter is demonstrated. A wideband tunable LO signal is generated in the OEO through adjusting the frequency difference between the optical carrier and the reflection notch of a phase‐shifted fiber Bragg grating.…”

“…As optoelectronic oscillator (OEO) exhibits the unique advantages of low phase noise, large bandwidth, and flexible tunability, it has been employed in many applications for generating microwave or millimeter wave signal, 11,12 detecting the low power RF signals, 13,14 and photonically downconverting the RF signals. [15][16][17][18][19][20] In References 13 and 14, the weak RF signals can be amplified when the frequency of the injection RF signal matches one of the modes in the multimode OEO. In Reference 15, an RF receiver based on a PM assisted with an optical filter is demonstrated.…”

“…In these structures, the RF signal and LO signal are introduced into different RF ports of the modulator, and their bias phases need to be finely set to implement the single sideband (SSB) modulation or carrier suppression modulation so as to achieve the maximum conversion efficiency as possible. As optoelectronic oscillator (OEO) exhibits the unique advantages of low phase noise, large bandwidth, and flexible tunability, it has been employed in many applications for generating microwave or millimeter wave signal, detecting the low power RF signals, and photonically downconverting the RF signals . In References 13 and 14, the weak RF signals can be amplified when the frequency of the injection RF signal matches one of the modes in the multimode OEO.…”