ABSTRACT
A scheme to generate a frequency 32-tupling millimeter wave (mm-wave) is proposed, enabled by two dual-parallel polarization modulators (DP-PolMs) in cascade. By properly controlling the amplitude and the phase shift of the radio-frequency (RF) driving signal applied to two DP-PolMs, the main optical components at the output of the DP-PolM are ±16th order optical sidebands and the central carrier. After the central carrier is canceled by the polarization multiplexing structure, the ±16th order optical sidebands are beaten in the photodetector; then the frequency 32-tupling mm-wave can be achieved. The optical sideband suppression ratio (OSSR) and the radio-frequency spurious suppression ratio (RFSSR) of the generated signal are 52 and 47 dB in simulation, which are consistent with the theoretical analysis values 53.7 and 47.7 dB. The influence on the OSSR and RFSSR of the generated signal by the key parameters of devices deviating from the theoretical analysis value i are investigated.
ABSTRACT
An novel method to generate 40-tupling frequency millimeter (MMW) based on the remodulation of MZMs and a novel radio over fiber (ROF) system to transmit the generated MMW are proposed. At the central station (CS), the ±4th order sidebands generated by two Mach-Zehnder modulators (MZMs) in parallel are used as the optical carriers for the remodulation. The radio frequency (RF) signal for the remodulation can be generated by injecting the ±4th order sidebands in the photodetector (PD). The main components in the signal after remodulation are ±4th, ±12th and ±20th order sidebands, among them, the +20th sideband is filtered out by a fiber Bragg grating (FBG). After the +20th order sideband is modulated with the downlink data, the ±20th order sidebands are combined again and transmitted to the base station (BS) by optical fiber. At the BS, a part of -20th order sideband is filtered out with a FBG, and with which the uplink data is modulated on it and sent back to the CS for carrier wave reuse. The 40-tupling frequency MMW signal with downlink data is generated by beating the output signal from FBG in the PD. In the case of data rate is 2.5G/bps and the bit error rate is less than 10-9, the transmission distance can exceed 90 km, the power penalty of the uplink and downlink is less than 1 dB and 0.29 dB, respectively. Our scheme has simple structure, high frequency multiplier factor, it has important application prospects in MMW technology.