The integration of wideband electronic attack (EA) and electronic protection (EP) is a growing concern in electronic countermeasures (ECMs) as wireless technology advances. However, electronic hardware in conventional ECMs already approaches its bandwidth ceiling, making the solutions for high-performance, scalable, and reconfigurable optical signal processing extremely imperative, such as photonic RF memory (PRFM). This work demonstrates a phase–amplitude evolution mechanism in PRFM, where phase evolution enables radar range deception and amplitude evolution serves to scramble and diffuse the optical quantum noise for enhanced communication security. Founded on this, a novel microwave photonic front-end using orthogonal polarizations was developed and experimentally executed. In EA tasks, a 12-GHz optical frequency comb (OFC) signal was cyclically stored for$1000~\mu $s with high fidelity, creating 400 range false targets. Thanks to the Doppler frequency replication based on coherent OFC technology, the number of range–velocity compound 2-D false targets increased to 4400 (
400×11). In EP tasks, a 4-Gbaud QPSK signal was initially encrypted into a
216-QAM/quantum noise stream cipher (QNSC) signal and underwent 200 security adjustments in the loop at an 8% error vector magnitude (EVM) penalty, resulting in a nearly fourfold privacy improvement. Tuning of the number of circulations can compatibly reconstruct the jamming and security levels. Furthermore, an SNR monitoring probe was involved in the case of radar intrusion into communications, prompting communication tasks to adaptively respond to the threats. Therefore, our scheme pioneers the first integration of signal storage, 2-D radar jamming, private communication, security reconfiguration, and adaptive risk response in a wideband microwave photonic front-end, strongly addressing the reinforcement need of future ECMs.
A new structure for storing a radio frequency (RF) signal utilising a fibre-optic delay line is presented. It is based on a frequency shifting recirculating delay line loop for the RF pulse storage, which prevents lasing and enables multiple recirculations and long storage time to be realised. The new photonic RF memory (PRFM) can realise a long reconfigurable storage time, wide instantaneous bandwidth and high dynamic range. Experimental demonstration of the frequency shifting loop based PRFM has been carried out for the first time, showing a long and reconfigurable storage time of more than 300 μs with high signal fidelity.
We present an extension of the atomic frequency comb protocol that utilizes the Stark effect to perform noisefree, on-demand, control.An experimental realization of this protocol was implemented in the Pr 3+ :Y 2 SiO 5 solid-state system, and a recall efficiency of 38% for a 0.8 μs storage time was achieved.Experiments were performed with both bright pulses as well as weak-coherent states, the latter achieving a signal-to-noise ratio of 570 ± 120 using input pulses with an average photon number of ∼0.1.The principal limitation for a longer storage time was found to be the minimum peak width attainable for Pr 3+ :Y 2 SiO 5 .We employ an adaptation of an established atomic frequency comb model to investigate an on-demand, wide-bandwidth, memory based on Eu 3+ :Y 2 SiO 5 .From this, we determine that a storage time as long as 100 μs may be practical even without recourse to spin-wave storage.
We report on the high-efficiency storage and retrieval of weak coherent optical pulses and photonic qubits in a cavity-enhanced solid-state quantum memory. By using an atomic frequency comb (AFC) memory in a Pr 3+ :Y 2 SiO 5 crystal embedded in an impedance-matched cavity, we stored weak coherent pulses at the single photon level with up to 62% efficiency for a pre-determined storage time of 2 µs. We also confirmed that the impedance-matched cavity enhances the efficiency for longer storage times up to 70 µs. Harnessing the temporal multimodality of the AFC scheme, we stored weak coherent time-bin qubits with a record (51 ± 2%) efficiency and a fidelity over (94.8 ± 1.4)%, limited by imperfections in the qubits creation and measurement.