Direct Reversible Coupling of Mechanical and Electromagnetic Waves in Passive Media: The Zero-Bias Limit

This record deposits the IEEE-formatted manuscript “Direct Reversible Coupling of Mechanical and Electromagnetic Waves in Passive Media: The Zero-Bias Limit”, which develops a theoretical framework for passive, reversible transduction between acoustic (mechanical) waves and optical (electromagnetic) waves within a single piezoelectric semiconductor (e.g., GaN or ZnO) in the zero-bias regime (no external electrical power). The deposition is intended to establish a citable, timestamped public record of the model assumptions, derived thresholds, and conceptual device proposal (“Passive Phonolume”) for long-term academic provenance and reproducibility. Key contributions:• Quantifies the frequency/energy gap between audible phonons and visible photons using Planck’s relation, motivating the stringent requirements of truly passive sound↔light conversion.• Derives resonant energy accumulation in a longitudinal acoustic rod (including damping via Q) as a pathway to increase mechanical energy density in the zero-bias limit.• Formulates bidirectional coupling mechanisms: sound→light via piezoelectric electroluminescence (with envelope phase preserved in the intensity modulation) and light→sound via radiation pressure and photoelastic excitation under intensity modulation.• Introduces an explicit stress/field threshold linking piezoelectric constitutive relations to a bandgap-scale critical field across an effective unscreened region (“fear equation”), and evaluates representative numerical bounds for ZnO and GaN.• Analyzes reciprocity, impedance mismatch at the air–crystal interface, and practical efficiency limits, and proposes the Passive Phonolume as a proof-of-principle platform grounded in established physics.• Provides a phenomenological coupled-mode envelope model and a transient simulation illustrating energy-transfer dynamics under damping.