Research Of The Electro-optic Modulation Technology And The Driving Source

Space optical communication is based on laser for the carrier,the atmosphere as a way of transmission medium for data transmission,which has the advantages of high speed of communication,a large capacity of information,good performance on anti-jamming and secret,and it has a very broad application prospects.High-speed transmission system of the laser communication is an important part of the spatial laser communication system,and the high-speed electro-optic modulation technology as one of the most typical modulation way is the most important part in the transmission system of the laser communication,one of the key technologies to achieve high power and high rate laser communication.In this paper,the electro optic modulation technology and electro-optical modulation driving source has carried on the detail study.We have achieved the following work:Firstly,the paper has a detail introduction on the basic theory of electro-optic modulation and working principle of the modulator,including the electro-optic effect,which is the physical properties of electro-optic crystal,the working process of the electro-optic modulator,and the classification of electro-optic modulation mode.Then this paper introduces the determination of linear working point of electro-optic modulator and its electrical properties,and analyses the influence on the modulation bandwidth which caused by the transit time and peripheral circuit.Secondly,according to the modulating characteristics,each part of the electro-optic modulation driving source is analyzed,designed and made,mainly includes built-in high frequency signal generator,high voltage power amplifier circuit,high DC voltage source circuit and DC bias circuit.Thirdly,considering the influence on electro-optic modulator caused by the variation of external environment temperature,and discussed the temperature properties of electro-optic modulator in these three aspects which contained the output light intensity with different modu-lation modes of electro-optic modulation,the phase delay and the output light transmitt-ance.Fourthly,based on the electro-optic modulation theory researched,the working characteristic of elect ro-optic modulator has been verify using specific experimental process and the electro-optic modulation driving source circuit have been designed.Through the electro-optic modulation experiment on the laser communication,we have verified the working performance of the electro-optic modulator and its driving source.Under the designed driving circuit with the existing electro-optical modulator,compared to the original 8KHz,the modulation speed has increased,and it can reach 3Mbps.The simulation results with different parameters of the modulator varies with temperature illustrate that the linear operating point of the modulator easily affected by temperature changes,and falls into non-linear region,and leading to the output characteristic of the modulator has an error occurred.