Research On Design And Manufacturing Of High-performance Optoelectronic Oscillator And Its Applications

Microwave photonics combines the advantages of microwave technology and photonic technology,and is widely used in the fields of microwave generation,processing,control and distribution.One of the most important research areas is optoelectronic oscillator(OEO)because of its ultra-low phase noise performance.Based on the analysis,this thesis focuses on reducing noise of OEO and further improving its performance,and then explores the method of microwave frequency comb generation and absolute distance measurement(ADM)based on OEO.In terms of improving the performance of OEO:1)The theoretical model of OEO is studied,and the influence of optical amplitude noise and flicker noise on OEO phase noise is analyzed.The modified quisi-linear model reveals that the close-in phase noise of OEO obeys the 1/f3 law,which agrees well with the experimental results.2)In order to suppress the optical amplitude noise,which deteriorates the phase noise of OEO,caused by optical fiber,a method is proposed by adding a gain saturated semiconductor optical amplifier into the OEO structure.Experimental results show that the phase noise of OEO is reduced by 3 dB.3)Phase-locked loop parameters of cavity length stabilization technology of OEO based on phase-locked loop is studied.The optimized loop bandwidth of phase-locked OEO is 50 Hz.4)An optical time delay system(OTDS)is proposed,which cascades optical switch network and bidirectional optical delay line.The optical path of OTDS can be continuously adjusted on the order of meters,which could stabilize cavity length of OEO over a large temperature range.5)Combining the above work with engineering design,a high-performance OEO prototype is manufactured.The output frequency of OEO prototypes are 10 GHz and 16.5 GHz with phase noise lower than-140 dBc/Hz@10 kHz,side mode suppression ratio of 75 dB and frequency stability of 4.2×10-11@10 s.The prototype can work at 0-40? and passes the vibration test with power spectral density of 0.04 g2/Hz.In the applications of OEO:1)A microwave frequency comb is generated based on externally modulating OEO.The filter in the classic OEO structure is replaced with a mixer.Therefore,the OEO could be modulated externally and the oscillation frequency bandwidth is increased,meanwhile maintaining low phase noise.The spectrum bandwidth of the generated microwave frequency comb is 7?14 GHz,and the adjustable frequency interval reaches 5 GHz.The phase noise of each spectral line is-115 dBc/Hz@10 kHz.2)An ADM method based on alternately oscillating OEOs is proposed.The reference and measurement loops can be completely separated by a 2×2 crossbar optical switch.The cavity length drift of OEO is eliminated by reference and measurement loop oscillating alternately,so that there is no need to control cavity length and the ADM system is simplified.The relative measurement accuracy reaches 4.5×10-10 at an emulated 7.5 km distance with 40 ms per measurement.The measure-ment error of a 20 mm/s target is within ±5 ?m.