Selective Activation of R‐ and N‐Line Lasing in Cr ³⁺ Substituted LaGaO ₃ : Toward Tailored Photonic Functionality

ABSTRACT Ceramic lasers have emerged as a revolutionary class of solid‐state lasers, offering good thermal management, uniform emission cross‐sections, and the ability to incorporate high concentrations of active laser ions. Ceramic lasers are emerging as promising gain media, owing to the ongoing progress in high‐power lasers, low lasing threshold, developing new doping materials, and extending their functional wavelengths. In this work, we report lasing action without external cavities from Cr substituted LaGaO 3 polycrystalline oxide perovskite, a wide bandgap (4.4 eV) perovskite with an orthorhombic Pbnm crystal structure. Upon 488 nm continuous‐wave excitation, the Cr 3+ ions exhibit sharp emissions in the near‐infrared (NIR) region due to transitions from the 2 E excited state to the 4 A 2 ground state. Depending on the Cr 3+ concentration, lasing from single‐ion (R‐line) and pair‐based (N‐line) emissions can be selectively activated. Power‐dependent photoluminescence measurements show a clear lasing threshold, while the temperature‐dependent studies ranging from 120 to 393 K confirm lasing stability across a wide thermal range. Studies reveal that microcrystals present in the system may act as resonators. The lasing in the NIR region without external optical cavities promotes device miniaturization. Our results establish a new pathway for realizing compact, efficient, and wavelength‐flexible ceramic lasers.