Spectral Overlap Limits Optical Gain in Quantum Heterostructure Photonic Devices

Abstract

Increasing carrier density is commonly expected to enhance optical gain. Here, a universal crossover is identified in which interaction-induced spectral broadening competes with the intrinsic energy separation of optical states. When Γavg/Δ approaches unity, spectral overlap suppresses transition selectivity and limits gain, revealing a fundamental design constraint for quantum-confined photonic devices.