The integrated radar jamming and secure communication system providing both false target and high physical layer transmission security will play an important role in future electronic warfare systems. In this letter, we present and experimentally validate a novel photonics-based integrated system that combines radar jamming with secure communication. The system incorporates velocity and range false targets generation for effective radar deception jamming, along with a secure communication function boasting a remarkable key space of 10 ¹⁵⁶ with the help of Li's hyperchaotic model. The Ka-band radar deception jamming and chaotic encrypted communication signals are simultaneously generated by a photonic frequency upconverter, which consists of a Mach–Zehnder modulator (MZM), an optical filter, an in-phase/quadrature (I/Q) modulator, and dual-drive Mach–Zehnder modulator (DDMZM), and a photodetector (PD). In a proof-of-concept experiment, the generated velocity deception jamming signal extended beyond 40 GHz, achieving a remarkable spurious suppression ratio of over 30 dB. The range deception jamming is also investigated. Meanwhile, the chaotic encrypted 4 Gbaud 16 quadrature amplitude modulation (16QAM) and 32 quadrature amplitude modulation (32QAM) orthogonal frequency division multiplexing (OFDM) signals over a distance of 1 m are successfully demonstrated. The proposed scheme can reduce enemy radar detection capabilities and enhance communication security ability, which is required by future electronic warfare systems.

In this article, we propose a novel photonic-based integrated scheme that simultaneously achieves radar jamming signal generation and chaotic encrypted wireless communication. The velocity deception jamming signals are generated with a high spurious suppression ratio of 31.9–33.2 dB. Additionally, the range deception jamming has been efficiently executed. Simultaneously, an encrypted 64-quadrature amplitude modulation (64QAM) OFDM signal with a key space of 10 $^{50}$ is transmitted over a 1.5-m wireless link, meeting the hard decision forward error correction (HD-FEC) threshold of 3.8 $\times$ 10 $^{-3}$ , corresponding to a net rate of 9.9 Gbit/s. In addition, a maximum modulation error ratio (MER) of 21.4 dB is achieved below the error vector magnitude (EVM) threshold of 9%. The proposed scheme effectively combines the capabilities of degrading enemy radar detection and enhancing one’s wireless communication security, which may be a potential application for electronic countermeasures in the future.

A simplified maximum likelihood sequence estimation (MLSE) based on Viterbi algorithm has been proposed. Experimental results show that compared with the conventional MLSE, the proposed algorithm saves the multiplication by 25% with no sensitivity penalty when the memory length of MLSE is 2 both in the 25 Gb/s non-return to zero (NRZ) and 50 Gb/s four-level pulse-amplitude modulation (PAM-4) transmission systems. In order to further reduce the number of multiplications in the 50 Gb/s PAM-4 transmission system, we use 75 taps of feed-forward equalization (FFE) to equalize the received PAM-4 signal into duo-binary four-level pulse-amplitude modulation (DB-PAM-4) signal and then use MLSE with the memory length of 1 to decode, which improves the sensitivity performance by 1.8 dB and reduces the computing complexity by ~98% compared with conventional MLSE (L=4) method. As a result, 10-km C-band transmission of 50 Gb/s PAM-4 signal is achieved using optical transceivers with a combined 3-dB bandwidth of ~8 GHz, and only 107 multiplications are required by using our proposed simplified algorithm for equalization.

We experimentally investigate transmitting high-order quadrature amplitude modulation (QAM) signals with carrierless and intensity-only measurements with phase retrieval (PR) receiving techniques. The intensity errors during measurement, including noise and distortions, are found to be a limiting factor for the precise convergence of the PR algorithm. To improve the PR reconstruction accuracy, we propose a distortion-aware PR scheme comprising both training and reconstruction stages. By estimating and emulating the distortion caused by various channel impairments, the proposed scheme enables enhanced agreement between the estimated and measured amplitudes throughout the PR iteration, thus resulting in improved reconstruction performance to support high-order QAM transmission. With the aid of the proposed techniques, we experimentally demonstrate 50-GBaud 16QAM and 32QAM signals transmitting through a standard single-mode optical fiber (SSMF) span of 40 and 80 km, and achieve bit error rates (BERs) below the 6.25% hard decision (HD)-forward error correction (FEC) and 25% soft decision (SD)-FEC thresholds for the two modulation formats, respectively.By tuning the pilot symbol ratio and applying concatenated coding, we also demonstrate that a post-FEC data rate of up to 140 Gb/s can be achieved for both distances at an optimal pilot symbol ratio of 20%.

We experimentally demonstrate 112-Gb/s/λ PAM-4 transmission based on 25-Gb/s optics. Over 31-dB power budget is achieved by using OLT-side pre-equalization, amplification and only simple FFE in ONU.