Lasing-like dynamics with virtual gain driven by complex-frequency excitations

Area of Science:

• Non-Hermitian photonics
• Quantum optics
• Materials science

Background:

• Complex-frequency excitation offers novel control over light-matter interactions.
• Virtual loss has been explored for coherent perfect absorption.
• Virtual gain in optical systems remains underexplored.

Purpose of the Study:

• To theoretically and experimentally demonstrate lasing-like dynamics using virtual gain in passive microcavities.
• To investigate the role of virtual gain in counteracting material and radiation losses.
• To explore the coexistence of lasing-like behavior and perfect absorption.

Main Methods:

• Utilizing complex-frequency excitations in passive whispering-gallery-mode microcavities.
• Theoretical modeling and experimental validation of virtual gain effects.
• Analyzing transmittance, response regimes, and threshold-like phenomena.

Main Results:

• Demonstrated lasing-like dynamics in a passive microcavity via virtual gain.
• Observed instantaneous transmittance exceeding unity, saturating at a quasi-steady value.
• Identified a threshold-like point leading to a divergent, exponentially growing response, mimicking laser transient buildup.
• Achieved robust coexistence of lasing-like behavior and perfect absorption, tunable by virtual gain.

Conclusions:

• Virtual gain provides a versatile framework for manipulating non-Hermitian light-matter interactions in passive systems.
• This approach bypasses the need for population inversion or active media, unlike traditional lasers.
• Potential applications include advanced sensing, optical communications, and energy storage devices.