Photonic Phase-stabled Transmission Method Based On Passive Compensation

Photonic phase-stabled transmission plays an important role in many military or civil fields,such as communication,distributed radar,deep-space detection,etc.Phasestabled transmission is developing towards the direction of large bandwidth,high precision,fast compensation with the rapid growth of information and the continuous progress and iteration of communication technology.And its transmission forms are also becoming more and more diversified.Passive compensation does not require the use of compensation devices,it has the advantages of wide range compensation and fast compensation.Therefore,the study of photonic phase-stabled transmission based on passive compensation has certain academic significance and value.This thesis reviews the research background and research status of photonic phasestabled transmission,and then summarizes the advantages and disadvantages of various phase-stabled transmission technologies.On this basis,the basic structure and principle of photonics passive phase-stabled compensation are studied,and a phase-stabled transmission system based on passive compensation is proposed.The compensation performance models of this system are analyzed and simulated,and relevant experiments are taken to verify them.Finally,combining the practical application scenarios of photonic phase-stabled technology,an uplink transmission based on passive phase stabilization is designed,and theoretical analysis and experimental verification are conducted.The main research results of this thesis are as follows:1)A photonic phase-stabled transmission based on passive compensation is proposed.And the use of dual-electrode Mach-Zehnder modulator(DEMZM)ensures that the system can transmit local oscillator signal and broadband signal at the same time.By mixing two signals under the same transmission delay jitter,it can directly offset the signal phase jitter introduced during the transmission,and can realize faster phase compensation of the broadband signal with a simpler structure.On this basis,the relevant model of the system about the principle of phase stabilization and compensation performance is established.And the concept of compensation suppression ratio is proposed to measure the performance of compensation bandwidth and compensation speed;The above model is verified by relevant simulations.The experimental results show that the system can compensate signals with a center frequency of 7.2 GHz and a bandwidth of 400 MHz,and the external jitter can be compensated is fast to 1 kHz.The transmission bandwidth of the system increases with the increase of the center frequency of the transmitted signal.The compensation speed of the system is inversely proportional to the length of the system’s optical fiber link.2)Based on the research of simulation analysis,relevant experiments are carried out.First,the principle of phase stabilization is verified.The experimental results show that when the transmitted signal of the system is 7.2 GHz,the root mean square(RMS)jitter of the free running signal is 5.46 ps,and the RMS jitter of the compensated signal decreases to 0.1 ps,which indicates that the system has a good effect of phase stabilization;The verification experiments on the performance of compensation bandwidth and compensation speed are designed,and the results are in good agreement with the simulation;On this basis,the transmission experiment of QPSK signal with the center frequency of 7.2 GHz and bandwidth of 50 MHz is carried out.The error vector magnitude(EVM)of signal without and with compensation are 10.9%and 8.56%respectively,which further explains the system’s stable phase transmission performance for broadband signals.3)An uplink transmission based on passive phase stabilization is designed.The related analog transmission performance is tested,including the stability of transmitted signal,flatness and the spurious free dynamic range(SFDR)of the system.The experimental results show that the frequency instability of 2 GHz transmitted signal is 7.86×10-12 at 100 s average time without compensation,while it is 1.08×10-14 with compensation,about two orders of magnitude are optimized;The digital signal transmission performance of the system is tested.PSK and FSK signals are transmitted successively.The experimental results of free running signal and compensated signal show that the system has a good compensation effect on the transmission stability of digital broadband signals.