Research On Transmission Technology Of Radio Over Fiber Based On Direct Modulation

Radio over fiber(ROF)technology is one of the important applications of microwave photonics.It combines the advantages of optical fiber communication technology and microwave communication technology,and is widely used in fiber-optic communications,intelligent transportation systems,radio telescopes,remote sensing and other fields.The transmission technology of radio over fiber based on direct modulation has the characteristics of simple structure and low cost.With the increasing requirements of communication system for low cost,low power consumption and small volume,the direct modulation circuit has a very high competitive advantage.In this paper,the research background of Ro F technology,the development status at home and abroad and the theory of Ro F transmission are introduced.The related performance indicators of the link are studied and analyzed.The transceiver module based on direct modulation Ro F technology is designed and manufactured.The main contents of this article include:1?In this paper,the drive and temperature control technology of butterfly package laser based on direct modulation are studied.The constant power driving and constant temperature control scheme are adopted to overcome the problem that the laser output power varies greatly with temperature and the link power consumption is large.At the same time,the coaxial direct modulation laser drive technology is studied in this paper.Because there is no TEC integrated in the coaxial laser,the external thermistor and TEC are added to enhance the power stability of the coaxial laser in a wide temperature environment.And design the preamplifier circuit,using the circuit simulation and impedance matching design in ADS software.2.Using the above-mentioned RF laser modulation transmission system,and then designing the light receiving and amplification module to make the link meet the index requirements.At the same time,the optical signal fault monitoring module is designed to monitor and monitor the receiving condition of the receiving module.3.Using vector network analyzer,spectrum analyzer,and optical power meter to build the test link,and perform performance tests on the transceiver module.The results show that both lasers achieve a maximum output power of 10 d Bm and link power consumption less than 4.5W.When the ambient temperature is-40? ? 70 ?,the optical power change is less than ± 0.3 d B,the wavelength of the butterfly packaged laser changes by 0.062 nm,and the wavelength of the coaxial packaged laser changes by 2.25 nm.When the operating frequency is 1.09 GHz,the 1d B compression point is greater than 10 d Bm.Under the condition of wide temperature test,the link gain is-10 db ± 0.5db when the optical power of the input detector is0?3d Bm.