| Microwave photonic technology (RoF) is to employ the method for photonics toprocess microwave signals, which mainly includes microwave signal generation,transmission, filtering, time delay and phase shift,etc. Due to the advantages of stableinformation channel signal, low loss, high bandwidth, immuning to EMI and EMP, lessweight and easy to maintain, the RoF technology is widely utilized in military and civildomains.The features、applications and the development at home and abroad of microwavephotonic link are discussed in the paper. A key research on the principles and mainperformance parameters of direct modulation microwave photonic link is made. Basedon RoF technology, a10MHz～4GHz UWB microwave photonic link is designed. Inaddition, a gain amplifier is designed to improve the link gain. Meanwhile, based on theinternal structure and equivalent circuit of the semiconductor laser with TO package, theresearch on the impact of the length of the pin on the flatness of the link is made, andthe match circuit of the semiconductor laser is designed in ADS. Moreover optical fiberdispersion effect and direct modulation frequency chirp phenomenon are researched andthe corresponding compensation measures are put forward.Finally, the link is tested by using the test systems composed of vector networkanalyzer、dc power supply、high frequency cable、signal source and spectrum analyzer.The results obtained demonstrate that the average gain is8.4dB with the flatness±1.5dB; the input and output vswr are no more than2; when the offset is10KHz, the phasenoise of microwave photonic link is5.5dBc/Hz more than the through link；harmonicpower of microwave photonic link is10dBm more than the through link during the wholefrequency range. The link meets the need of the project and is widely used in all kindsof areas. |
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