Chirped Pulse Analysis and Control in Non-Hermitian Scattering Systems using Complex Time Delay

TL;DR

This paper explores how complex time delays influence chirped pulse propagation in non-Hermitian scattering systems, enabling precise control over pulse timing and frequency shifts.

Contribution

It establishes a theoretical and experimental link between chirped pulse behavior and complex Wigner-Smith time delay in non-Hermitian systems, demonstrating tunable pulse control.

Findings

Chirped pulse time shift depends on real and imaginary parts of complex time delay.

Center frequency shift of the pulse is proportional to the imaginary component of complex time delay.

Complex time delay can be used to achieve near-zero pulse time shift across various frequencies.

Abstract

We theoretically and experimentally establish a connection between linearly chirped pulse propagation properties and the complex generalization of Wigner-Smith time delay for both transmitted and reflected pulses in linear and dispersive reverberant non-Hermitian scattering systems. We demonstrate that the time shift of the chirped pulse depends on both the real and imaginary parts of the complex time delay of the scattering system. We also show that the chirped pulse experiences a center frequency shift that is directly proportional to the imaginary component of complex time delay, similar to that found in Giovannelli and Anlage (2025). Using these insights, we then demonstrate how complex time delay can be harnessed to systematically tune the propagation properties of a chirped pulse such that a near-zero time shift can be achieved for a wide range of pulse center frequencies in a resonant scattering system. Overall, this work broadens the utility and establishes the physical significance of complex time delays in non-Hermitian settings.