摘要
In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,and polarization I/Q demodulators in theory and experiment.The use of two coherent combs avoids precise optical alignment,and a numerical filter in digital signal processor(DSP) enables an ideal rectangular frequency response in each channel without any ultra-narrow optical filters.Besides,due to the use of polarization I/Q demodulation,ambiguous frequency estimate in direct detection can be avoided and the amplitude,phase mismatch in traditional I/Q demodulation can be mitigated.In experiment,we use two coherent OFCs with the free spectrum range(FSR) of about 40 GHz to demonstrate the channelization scheme with seven channels,500 MHz channel spacing and frequency coverage from 3.75 GHz to 7.25 GHz.The input RF tones are accurately down-converted to an intermediate frequency(IF) with a maximum frequency error of 110 kHz.Meanwhile,crosstalk and spurious free dynamic range(SFDR) of the scheme are also discussed.
In this work, we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency （RF） channelization scheme based on dual coherent optical frequency combs （OFCs）, regular optical de-muxes, and polarization I/Q demodulators in theory and experiment. The use of two coherent combs avoids precise optical alignment, and a numerical filter in digital signal processor （DSP） enables an ideal rectangular frequency response in each channel without any ultra-narrow op- tical filters. Besides, due to the use of polarization I/Q demodulation, ambiguous frequency estimate in direct detection can be avoided and the amplitude, phase mismatch in traditional I/Q demodulation can be mitigated. In experiment, we use two co- herent OFCs with the free spectrum range （FSR） of about 40 GHz to demonstrate the channelization scheme with seven chan- nels, 500 MHz channel spacing and frequency coverage from 3.75 GHz to 7.25 GHz. The input RF tones are accurately down-converted to an intermediate frequency （IF） with a maximum frequency error of 110 kHz. Meanwhile, crosstalk and spurious free dynamic range （SFDR） of the scheme are also discussed.
基金
supported in part by the Major State Basic Research Development Program of China ("973" Program) (Grant No. 2012CB315705)
National Natural Science Foundation of China (Grant Nos. 61107058, 61120106001)
the National High Technology Research and Development Program of China ("863" Program) (Grant No. 2011AA010306)
the Fundamental Research Funds for the Central Universities of China
关键词
信道间隔
解调器
光频梳
偏振
相干
RF
射频
光子
optical frequency comb, polarization I/Q demodulation, microwave photonic, radio frequency （RF） signal processing
