Research On Phase-modulated Radio Over Fiber Technique And Its Applications

Microwave photonics is a new cross discipline in the field of information technology, based onwhich the microwave photonics technique is developed,combining the advantages of photonics technology, huge bandwidth, low insertion loss, easy multiplexing and anti-electromagnetic interferenc, and microwave engineering, high flexibility, broad coverage and easy mobility. It is playing an increasingly important role in the field of military defense and communications, related research has been carried by researchers at home and abroad, and has made significant progresses.In this dissertation, we conduct research work aiming at the application of phase modu-lation technique based on electrooptical modulation in the field of microwave photonics. Among this we have studied the basic principle of optical phase modulation, the operating characteristics of modulators, microwave over fiber transmission and its application of microwave frequency instantaneous measurement based on electrooptical phase modulatioa Mainly accomplished research work, as follows,1. The half-wave voltage of integrated optical waveguide phase modulator is investigated with spectrum analysis method. The operating property of phase modulator is studied. Based on the spectrum analysis of the microwave modulated optical signal, the half voltages from3GHz to8.5GHz microwaves are measured. And this provides a useful reference for further application.2. The characteristics of phase modulated radio over fiber transmission are investigated. The theoretical model of phase modulated radio over fiber transmission system is established. To solve the problem of microwave power fading of the transmission system, two measures are carried out. One is based on sing side-band transmission with FBG filter; the other is based on dispersion compensation with chirped FBG. In the experiment, the microwave signal of13.76GHz is recovered after transmission over40km single mode fiber, and the transmission performance with different symbol rates of modulated signal is tested and analyzed.3. The instantaneous measurement of microwave frequency based on phase modulation is realized. Due to the electronic bottleneck and limit bandwidth, the traditional electronic methods can not realize instantaneous frequency measurement (IFM) with wide range. We investigate a photonic IFM method based on phase modulated radio over fiber technique. And the way to broaden the range of measurable frequency and to improve measurement resolution is proposed. A measurable microwave frequency from10GHz to20GHz with an error within±0.5GHz is achieved with the established measurement system.