Optical frequency comb assisted reconfigurable broadband spread spectrum signal generation.

A photonic-assisted scheme for spread spectrum communication signals generation is proposed and demonstrated in this article. The spreading sequence and the baseband data codes are modulated on the photonic link by electro-optic modulators, and the spread spectrum process is completed through stream processing on the analog microwave photonic link. By combining optical frequency comb and injection locking technologies, the carrier frequency of the communication signals can be tuned over an ultra-broadband range of 3-39 GHz. In the proof-of-concept experiments, spread spectrum signals at 3 GHz and 6 GHz are obtained with a spread factor of 31. The analysis results indicate that the generated signals possess excellent reconfiguration, anti-interference, and anti-interception properties. Overall, our proposed scheme offers a flexible photonic architecture with significant potential in the application of ultra-broadband covert communication systems.

Deep-learning-assisted linearization for the broadband photonic scanning channelized receiver.

An autoencoder-residual (AE-Res) network is designated to assist the linearization of the wideband photonic scanning channelized receiver. It is capable of adaptively suppressing spurious distortions over multiple octaves of signal bandwidth, obviating the need for calculating the multifactorial nonlinear transfer functions. Proof-of-concept experiments indicate that the improvement of the third-order spur-free dynamic range (SFDR2/3) is 17.44 dB. Moreover, the results for real wireless communication signals demonstrate that the improvement of the spurious suppression ratio (SSR) is 39.69 dB and the reduction of the noise floor is ∼10 dB.