Research On Broadband Optical Channelization Technology

In modern electronic warfare,electronic warfare radio frequency signal receivers play an important role in the entire electronic reconnaissance system.At the same time,real-time monitoring of broadband radio frequency(RF)signals also has applications in phased array antenna arrays,communications remote sensing,and control systems.A very wide range of applications.The instantaneous bandwidth of a conventional RF channelized receiver is limited to a few GHz,Due to the advantages of low optical signal transmission loss,large operating bandwidth,etc.,photonic-assisted microwave photonic channelization has attracted wide attention of researchers in recent years.Researchers have proposed photon-assisted channelization architectures for a variety of different methods and objectives,such as spectral division by dispersion,spectral segmentation by multiple optical local oscillator frequencies(LO),and dispersion Fourier transform in the time domain to monitor the spectrum.These methods can handle wider bandwidths,but the performance of this microwave photonic channelization system can also be limited by factors such as resolution,measurement speed,temperature stability,and system cost.In this paper,we propose a novel channelization scheme based on chirped pulse based on frequency shift feedback pulsed laser source and delayed coherent detection.The scheme is mainly composed of two parts:The first part is a first-order diffracted ring cavity feedback formed by the core device Acousto-optic modulator(AOM),and the cavity can successfully generate a frequency-shift feedback FSF pulse signal.The time domain of the output pulse is periodic,and the phase of the pulse is chirped.Theoretically,we have found that the coherent detection of the chirped pulse and its own delayed signal produces an equivalent RF local oscillator signal.The second part of the scheme is delaying the coherent detection link.Adjusting the time delay between the two optical paths through the optical delay line can tune out local oscillator signals of different frequencies.Increasing the number of delay lines in parallel can achieve coexistence of downconverted multiple local oscillators that can be used in channelization.Based on this,the feasibility of a novel channelized receiver based on frequency shift feedback pulsed light source and delayed coherent detection are verified through experiments.Experiments have demonstrated a channelized receiver with five channels,100 MHz channel spacing,covering a spectral range of 500 MHz.The experimental results show that the image suppression is more than 30 dB,the average spurious-free dynamic range(SFDR)is 90.01 dB·Hz2/3,and the frequency resolution also has good consistency.The system has many advantages in structure,and can realize multiple channel and flexible and easy-to-control experimental configuration.Using higher frequency AOMs can increase the number of channels and enable wider spectrum RF reception.