Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers

TLDR

Two-photon‑pumped lasers promise frequency up‑conversion when phase matching is infeasible, yet their use has been limited by a lack of materials that combine efficient two‑photon absorption with easy population inversion. We demonstrate that colloidal perovskite nanocrystals can overcome this limitation. In toluene solutions of CsPbBr₃ nanocrystals we measured a two‑photon absorption cross‑section of 2.7 × 10⁶ GM, producing optical gain exceeding 500 cm⁻¹ in thin films. Coupling these nanocrystals to microtubule resonators yielded stable, low‑threshold two‑photon‑pumped lasing, establishing perovskite nanocrystals as a high‑performance gain medium for practical frequency‑up‑conversion lasers.

Abstract

Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 10(6) GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm(-1)) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.