Wideband and Ambiguous-Free RF Channelizer Assisted Jointly by Spacing and Profile of Optical Frequency Comb

Abstract

For civil and military applications, the ability to instantaneously capture and process wideband RF (radio-frequency) signal is of great importance. In this paper, a novel photonics-assisted RF channelized receiver aiming for instantaneous broadband RF signal reception is proposed and experimentally demonstrated. The channelizer is composed of two branches. In one branch, an optical frequency comb (OFC) is generated through a phase modulator (PM), while in the other the optical carrier is frequency-shifted via a polarization modulator (PolM) and then modulated by the captured unknown RF signal. Next, the frequency information of the unknown signal is derived from the frequency sum and the power difference of two specific beating tones, while the incorporation of the comb spacing and the amplitude profile of the OFC enable resolving the ambiguity cases. In the experiments, four receiving channels are constructed using five selected comb lines. The reception and analysis of several RF signals including single-tone, multi-tone and linear frequency modulation (LFM) ones within 1-40 GHz are experimentally validated, which can be extended up to 72 GHz in theory. The proposed channelizer is characterized with ambiguous-free capability, low measurement errors less than 2 MHz, and an SFDR of ∼92 dB•Hz 2/3 .

Review of Microwave and RF Photonic Channelizers using Optical Kerr Microcomb Sources

“…In addition, spectral slicing can be performed by stimulated Brillouin gain spectrum [46], wavelength division multiplexers (WDMs) [49], optical delay lines [42], FP etalons [11] [43] [12] [45] [52], free-space diffraction elements [41] and microresonators [74] [75], which act similarly to the periodic filters. As Fig.…”

Review of Photonic RF Channelizers based on Optical Microcombs

“…In [73], four discrete lasers provide different wavelengths to form a four-channel receiver, and it is obvious that this approach can only achieve a limited number of channels, which is not conducive to high-capacity broadband communications. Later, OFCs were proposed, which can be realized by a variety of mechanisms, including fiber nonlinear effects [40] [11], time lens [12] [44] [47] [52] [49] [51] and mode-locked laser [42] [53]. For instance, multi-wavelength optical carriers have been achieved via the four-wave mixing (FWM) effect in highly nonlinear fibers [40].…”

Photonic Multiple Microwave Frequency Measurement System with Single-Branch Detection Based on Polarization Interference

“…Generally, the photonics-assisted IFM system can be divided into three categories based on frequency-to-power mapping [4][5][6], frequency-to-time mapping [7,8], and frequency-tospace mapping [9][10][11][12][13]. The majority of frequency-to-power mapping systems rely on producing an amplitude comparison function (ACF), which constructs the relationship between the unknown microwave frequency and the optical or electrical power.…”

“…The frequency-to-space mapping method is widely adopted in photonic channelizers due to its real-time characteristics and the capability of measuring multi-tone broadband signals. In this case, the input microwave signals with high frequency are down-converted by a channelizer via Fabry-Pérot filters [9], fiber Bragg grating [10] or optical frequency combs (OFC) [11][12][13]. Among them, the OFCbased method is popular because of its lower resolution.…”

“…[12], a system based on a digital-signal-driven OFC can measure the unknown signals over 0-50 GHz in simulation. An experimental setup based on the spacing and profile of OFC is also proposed with less than 2 MHz over 1-40 GHz [13]. However, they are complex systems, such as ones using multiple photodetectors (PD) and modulators, which is difficult to achieve on a chip.…”