ENOB LDPC coding RF photonics Walsh–Hadamard transform (WHT) analog-to-digital converter bound states in the continuum carrier envelope phase channel optical power chromatic dispersion estimation constant composition distribution matcher constellation shaping conversion efficiency discrete multi-tone (DMT) dispersion electromagnetic camouflage and illusion faster-than-Nyquist four-wave mixing full data-carrying SC precoding (FDSP) high-resolution and low-cost higher order modulation format signal hybrid phase-change metasurface intensity-modulation and direct-detection (IM-DD) key consistency rate key distribution liquid crystal on silicon (LCoS) low-complexity metasurface carpet cloak microwave photonics modulation multi-channel