Random Laser: Disorder & Amplification Threshold

Light localization, scattering, and stimulated emission threshold

Scatterer density ρ 0.15 Gain coefficient g 0.50

Pump power P 0.50 Num photons 50

Random laser: Disordered medium with gain — scattering provides optical feedback.
ℓ_transport = 1/(ρσ) — transport mean free path.
Threshold: g·L_eff > 1 where L_eff ~ ℓ√(L/ℓ) (diffusive feedback). Above threshold: lasing spikes emerge in spectrum.