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Date of Publication:2014-01-01

Journal:光电子 激光

Volume:25

Issue:1

Page Number:123-127

ISSN No.:1005-0086

Abstract:We propose a photonics method of measuring microwave frequency based on
   photonic mixing. In this approach,a tunable microwave delay line(TMDL)is
   utilized to control the time delay between radio-frequency(RF)path and
   optical path.By employing two cascaded Mach-Zehnder modulators to
   realize photonic mixing,we can establish the relationship between
   microwave frequency and direct current(DC)optical power,and also our
   system has the advantage in reducing cost.After simulating and analyzing
   the established theory model,we can design the time delay between RF
   path and optical path,so that the system frequency measurement range
   will be optimized.The simulation results show that it is suitable for
   the frequency range of 1-6GHz to select the time delayDeltatau1between
   optical path and RF path 1around 15ps,and the time delayDeltataubetween
   the two RF paths around 20ps.In the experiment,a vector network analyzer
   is utilized to measure the time delay,we gotDeltatau1as
   17.7ps,Deltatauas 16.9ps,and then the measured frequency range of 1to
   6GHz with a measurement error less than0.2GHz is demonstrated
   experimentally.The source of the measurement error is mainly from the
   phase measurement uncertainty of the vector network analyzer and the
   power fluctuation of the laser.The measurement accuracy can be improved
   by taking appropriate measures.This method can provide a low cost
   photonics solution for microwave frequency measurement.

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