• • At 163 K, mixed-phase MAPbI3 nanoplatelets achieve zero wavelength shift under pump density variation, eliminating a critical instability that plagues perovskite lasers for interferometric and quantum applications.
• • Lasing threshold drops from 18.4 μJ cm⁻² at 293 K to 4.5 μJ cm⁻² at 163 K, a 75.5% reduction, enabling lower-power operation and reduced thermal load in integrated photonic circuits.
• • Tetragonal phase exhibits a blueshift of 0.4 nm μJ⁻¹ cm², while orthorhombic phase shows a redshift of 1 nm μJ⁻¹ cm²; the opposing signs allow cancellation in the mixed phase, with a thermo-optic coefficient of 7.5 × 10⁻⁴ K⁻¹.
• • Finite element simulations validate experimental shifts: tetragonal resonance moves from 780.86 nm at 296.62 K to 779.66 nm with a 10.70 K rise; orthorhombic shifts from 794.78 nm to 796.50 nm with a 1.69 μJ cm⁻² pump increase, confirming the mechanism for phase-dependent stability.