Intrinsic Bistability and Critical Slowing in Tm³⁺/Yb³⁺ Codoped Laser Crystal with the Photon Avalanche Mechanism

We present theoretically a novel intrinsic optical bistability (IOB) in the Tm³⁺/Yb³⁺ codoped system with a photon avalanche mechanism. Numerical simulations based on the rate equation model demonstrate distinct IOB hysteresis and critical slowing dynamics around the avalanche thresholds. Such an IOB characteristic in Tm³⁺/Yb³⁺ codoped crystal has potential applications in solid-state bistable optical displays and luminescence switchers in visible-infrared spectra.