Research On Photonic-assisted Microwave Frequency Measurement

Instantaneous frequency measurement is limited by manufacturing technology,and it is difficult for conventional electronical method to achieve a wide range of bandwidth measurement.Microwave photonics technology,which combines microwave technology and optical technology which has the advantages of low loss,large working bandwidth,small system size and anti-electromagnetic interference.It offers a new solution for improving the performance of instantaneous frequency measurement receiver.This thesis discusses the photonic techniques for frequency measurement with related indexes by theoretical analysis and simulation.The main work is described as follows:1.The basic principle of microwave photonic frequency measurement is introduced.The related modulators,polarization devices and the performance of microwave photonic links are mathematically deduced and analyzed.The mathematical analysis and simulation verification for different applications of the polarization controller are carried out.Considering the power fading induced by the disperation of the fiber,the link gain formula under different modulation formats is mathematically analyzed2.A frequency-microwave power mapping measurement scheme based on dual-polarization Mach-Zehnder modulator(DPol-MZM)is proposed.The scheme creates an amplitude comparison function(ACF)by operating two modulators integrated by DPol-MZM in different modulation modes.Simulation verifies the frequency measurement capability of the system at 0.2-27 GHz.The measurement errors are less than ±0.2 GHz in range of 0.6-13.5 GHz.3.A frequency-microwave power mapping measurement scheme based on Mach-Zehnder Modulator(MZM)is proposed.This scheme generates an ACF function by using the character that the light parallel to the principle axis of the MZM is modulated while the light perpendicular to that is not modulated.Simulation verifies the frequency measurement capability of the system at 0.2-31.8 GHz.The measurement errors are ±0.2 GHz in the range of 0.2-13.5 GHz.By adjusting the polarization state and the length of the fiber,the measurement range can be easily adjusted.By combining several frequency measurement interval with high-precision,the contradiction between the frequency measurement range and the frequency measurement accuracy can be solved.4.The frequency-optical power mapping type measurement scheme based on DPol-MZM is proposed.The scheme constructs an ACF function by implementing a pair of complementary filters through DPol-MZM and a length of polarization-maintaining fiber.Simulation verifies the frequency measurement capability of the system at 0.2-25 GHz.The measurement errors are less than ±0.15 GHz in the range of 0.2-25 GHz.5.The frequency-optical power mapping type measurement scheme based on MZM is proposed.The scheme realizes a pair of complementary filters through a MZM,an optical delay line(ODL)and a 90-degree optical hybrid coupler.Simulation verifies the frequency measurement capability of the system at 0.2-20 GHz.The measurement errors are less than±0.1 GHz in the range of 0.2-10 GHz.6.A channelized frequency measurement scheme based on a dual-polarization quadrature phase shift keying(DP-QPSK)is proposed.The scheme uses a DP-QPSK to construct a pair of optical comb with different line spacings.The signals with their frequency to be measured are mapped to different physical channels by two WDMs and IQ mixing structure.The frequency measurement accuracy can reach MHz in a range of 0-7 GHz..7.The existing polarization stabilization structure is incorporated into the proposed frequency measurement scheme based on DPol-MZM for improving the system stability.The theoretical analysis of the optimized scheme is carried out.