Super-sensing: 100-fold enhancement in THz time-domain spectroscopy contrast via superoscillating waveform shaping

Superoscillations, where a band-limited wave oscillates locally faster than its highest Fourier harmonic, result from destructive interference between the harmonics. Here, we demonstrate that superoscillations enable a 100-fold contrast enhancement of terahertz waves passing through two similar samples. By optimizing the time-domain contrast within a short observation window through relative phase adjustments of the fundamental harmonics, we achieve maximum contrast when wave intensity is minimized locally, leading to superoscillations. This enhancement is observed in both simulations with Gaussian harmonics and experiments with quasi-sinusoidal terahertz harmonics, promising advanced terahertz imaging applications in medicine, pharmaceuticals, standoff hazard detection, and nondestructive evaluation.