nanolaser

A nanolaser is a laser whose optical cavity and gain medium are at nanometer scales, enabling subwavelength light confinement and very small mode volumes. This can reduce lasing thresholds and pave the way for integrated on-chip light sources. Lasing occurs when optical gain compensates losses in the nanoscale cavity, often through Purcell-enhanced emission from quantum emitters such as quantum dots or dye molecules embedded in a nanocavity, or via semiconductor gain media.

Common platforms for nanolasers include dielectric nanobeam and photonic crystal nanocavities, semiconductor nanowire lasers, and nanodisks. Plasmonic nanolasers, also known as spasers, use metal nanostructures to achieve extreme confinement but face higher optical losses. Hybrid approaches combine plasmonic and dielectric elements to balance confinement and loss.

Materials used in nanolaser construction range from III-V semiconductors (such as GaAs and InP-based systems) and ZnO to colloidal quantum dots and perovskites. Some nanolasers have demonstrated room-temperature operation, with emission spanning visible to near-infrared wavelengths.

Key concepts in nanolaser research include strong confinement leading to large Purcell factors, reduced mode volumes, and potentially thresholdless behavior in certain regimes. Challenges include optical losses in metals, heat dissipation, fabrication precision, and integration with waveguides and other photonic components. Signal extraction and coupling efficiency to external optics remain active areas of development.

Applications span on-chip optical communications, sensing, biomedical imaging, and quantum photonics, where compact, efficient coherent light sources at the nanoscale can enable new functionalities.