Study of the generation of two frequency 16-tupling millimeter wave and transmission over fiber by remodulation with Mach–Zehnder modulators

A novel method to generate and two frequency 16-tupling millimeter wave (MMW) and distribute the generated MMW over fiber system (MMOF) with two base stations (BS) by the remodulation with Mach–Zehnder modulators (MZM) is proposed. At the central station(CS), the ± 4th order optical sidebands generated by a dual parallel MZM (DPMZM) are split into two branches, one of which is injected into a photodetector (PD) to generate the 8th harmonic of the RF drive signal of the MZM, which acts as the RF driving signal for the remodulation, and the other acts as the carrier for the remodulation. The remodulation is realized by injecting the outputs of the two branches into an MZM. After remodulation, the signal which contains mainly the ± 20th, ± 12th and ± 4th order optical sidebands is divided into two branches, in which the positive and negative sidebands are filtered out by two optical band-pass filters (OBPF) first and the 4th and − 4th order sidebands are filtered by two fiber Bragg gratings (FBG) later, with which the data of the downlink are modulated on it. At the two BSs, the 12th and − 12th order sidebands in the downlink optical signal are first filtered out by two FBGs, with which the data of the uplink are modulated onto it and transmitted to the CS via optical fibers for carrier reuse; the output signals of the FBGs are injected into two PDs to produce two 16-tupling frequency MMWs with the data of downlinks. The feasibility of our scheme is verified by theoretical analysis and simulation experiments. The main innovations of our designed scheme are that the modulation index of MZM is greatly reduced by using the remodulation method, the power utilization rate is greatly improved by using all the main sidebands and the cost of the system is reduced by using the two BSs structures with carrier reuse.