Research On High Frequency Microwave Generation Based On Brillouin Amplification And Optoelectronic Oscillators

In recent years,microwave photonic technologies and RoF(Radio-Over-Fiber)System based on microwave photonics are the focus of research in the field of Optics and radio frequency electronic fields.Microwave photonic technologies make the generation of high frequency microwave signal with optical devices possible.RoF system is an important application of microwave photonics technology,which combines radio frequency communication and optical fiber communication.The characteristic of fiber optic communication with wide bandwidth makes up the shortage of frequency resource starvation in wireless communication system.At the same time the optical generation structure of the microwave subcarrier signal is integrated into the central station.The demodulated signal is transmitted by the antenna at the base station.The technology of microwave generation is one of the key technologies in the system.This paper mainly implemented a research on the generation technology of microwave subcarrier at the center station and designed a novel structure for high frequency microwave generation.The structure consists of two components.One is the optoelectronic oscillator with improved structure,and the other is the part of Brillouin selection amplification.The main work is as follows:1.An improved double-loop opto-oscillator structure is proposed.By adjusting the phase of the phase shifter in the structure,the oscillator can be tuned to generate an oscillation frequency of Brillouin shift,and the linearly chirped Bragg grating(LCFBG)is used as the photon filter filtering out other oscillation modes;The modulation format of Mach-Zehnder modulator(MZM)in the oscillator structure is analyzed and simulated;The influence of the refractive index modulation depth and chirp parameters on the reflection spectrum of LCFBG is simulated and analyzed.2.The principle of stimulated Brillouin amplification is theoretically analyzed and verified by simulation,analyzing the influence of the change of pump power on the gain;Based on the optical oscillation structure and the Brillouin amplification principle,the simulation system was built.The oscillator's output frequency and the final beat output signal is deduced via the formula,also simulated,obtaining the signal that is about 34.4GHz,which is 3 times the oscillation frequency.