Rapidly Tunable Dual-Comb RF Photonic Filter for Ultrabroadband RF Spread Spectrum Applications

Abstract

Abstract-We demonstrate a rapidly frequency-tunable radio frequency (RF) filter using microwave photonics technology for ultrawideband RF spread spectrum applications. A pair of electro-optic frequency combs is arranged as a dispersive tapped delay line in a differential detection configuration to implement a programmable finite impulse response RF filter. Our photonic scheme enables both fast frequency tuning on the order of tens of nanoseconds and wide tuning range (>7.5 GHz) with minimal variation of RF gain and passband shape. The low control voltage (ca. 1 V) and the linear relationship between control voltage and passband frequency facilitate agile frequency tuning for processing of signals with time-varying frequency content, while differential detection increases the photocurrent by a factor of two and suppresses common mode intensity noise. We exploit the rapid tunability of the implemented filter to demonstrate dynamic tracking of frequency-hopped and chirped RF signals. An experiment that performs dynamic filtering of an input chirp signal (3.92-GHz center frequency, up-chirped by >2 GHz within 100 ns) obscured by strong broadband noise achieves ∼11-dB signal-to-noise ratio (SNR) improvement. The SNR obtained is in addition to that available from standard matched filtering or pulse compression processing, suggesting strong potential for enhanced resistance against broadband noise jamming.

Dual chirped microcomb based parallel ranging at megapixel-line rates

“…Our approach is a swept frequency version of multiheterodyne detection 23 of optical frequency combs, commonly referred to as dual-comb spectroscopy. This technique has attained widespread attention and application in (nonlinear) optical and THz spectroscopy 24 – 26 , optical microscopy 27 , 28 , distance measurement 29 – 31 , two-way time-frequency transfer 32 , microwave photonics 33 , multi-dimensional spectroscopy 34 , coherent anti-Stokes Raman imaging 35 , and recently demonstrated spectrally interleaved broadband spectroscopy with frequency swept electro-optical dual-comb 36 , 37 . This method decodes all individual low frequency (MHz bandwidth) channels using a single high speed (GHz) coherent ‘intradyne’ detector by radio-frequency multiplexing.…”

A Review of Photonic Generation of Arbitrary Microwave Waveforms

“…There is also a significant interest in the frequency chirp generations using Fourier pulse shaping and frequency to time mapping, especially the demonstration compact photonic integration [43], flexible tuning of chirp rate [37], control of chirp sign [44] and the ability of shaping the waveform envelop [45]. There are also applications of arbitrary waveform generation for measuring and compensating for multipath channel propagation that overcomes inter-symbol interference [46] and for rapidly reconfigurable RF filtering [38,47]. There are also significant activities in the field of waveform generation based on microwave photonic filtering, particularly the generation of triangular wave train [48,49].…”

Performance Analysis on Interference and Frequency-to-Time Mapping Based Frequency Hopping Receiver

“…For frequency hopping receivers, the hopping speed is one of the key characteristics since it is relevant to the anti-jamming and anti-interception performance. For analog receivers, the receiving linearity [2], [6], [12], [15], [25] and the receiving radio frequency (RF) gain [4], [5], [7], [13] are two important characteristics since they indicate the quality of the received signals by affecting the average signal-to-noise ratio (SNR). For the average SNR of the frequency hopping receiver, a time window with fixed duration should be chosen, because the receiving RF gain varies in different frequencies, and it affects the average SNR.…”