A Novel Radio on Fiber System for Frequency 32-Tupling Millimeter-Wave Generation and Transmission Using Polarization Modulators

Abstract

A new radio on fiber (ROF) scheme for generation and transmission frequency 32-tupling millimeter-wave (MMW) is proposed. At the central station (CS), six PoIMs are used to construct the ±16 order sidebands generator which can generate ±16 order sidebands. The sideband of +16th order is separate out by an optical interleaver from the output of ±16 order sidebands generator first, then the data of down-link signal is modulated on it. At the base station (BS), a portion sideband of −16th order from the down-link optical signal is separted out with a fiber Bragg grating (FBG) first, then the up-link data is modulated on it for carrier reuse. The remaining ±16th order sidebands from the FBG are beat in a photodetector (PD), then the frequency 32-tupling MMW signal with the down-link data is generated. The key part of this system is the ±16th order sideband generator, in which the ±16th order sidebands with the carrier component can be generated by adjusting the amplitudes and initial phases of the radio frequency (RF) signals loaded on the PoIMs, and the carrier can be cancelled by two 1×2 optical coupler with adjustable splitting ratio and 180° optical phase shifter (OPS). The principle of operation to generate frequency 32-tupling is theoretically analyzed and verified by simulation experiments. The optic sideband suppression ratio (OSSR) of the generated sidebands of ±16th order from the theoretical derivation and experiments are 29.974 dB and 29.793 dB, respectively, the RF spurious suppression ratio (RFSSR) of the obtained frequency 32-tupling MMW from theoretical derivation and experiment are 23.960 dB and 23.814 dB, respectively, which verifies the feasibility of our method. The transmission experiments are carried out. For 30 km fiber with 2.5 Gbps data rate, the Q value and power penalty for up-link and down-link are greater than 6 and less than 0.4 dB, respectively.