Spectral Narrowing in a Subwavelength Solid-State Laser

Abstract

The association of metallic nanostructures and solid-state gain media has recently led to the emergence of functional platforms for nanolasing with relevant features such as chemical and thermal stability and the absence of photobleaching. In this work, we demonstrate that the incorporation of plasmonic nanoparticle chains on a Nd3+-doped solid-state laser platform enables nanoscale laser emission at the technologically relevant spectral region of telecom (λe = 1385 nm), outside the spectral response of the plasmonic resonance of the nanoparticle chains. In addition, we experimentally show that the plasmonic chains improve the monochromaticity of the solid-state laser, thus, attaining spectral narrowing of the laser line by up to 38% depending on the pump wavelength. The effect of the plasmon driven absorption enhancement in the vicinities of the Ag nanoparticle chains is analyzed by tuning the optical pump in a broad spectral range (580–890 nm) at different Nd3+ transitions that overlap the spectral response of the longitudinal plasmonic mode of the chain. Theoretical insight shows that the plasmon-induced narrowing of the laser linewidth close to the nanoparticle chains can be related to the modification of the effective pump rate within the active medium, which is produced by the excitation of the localized plasmonic mode. The work constitutes a step forward in the development of high-quality and highly integrated photonic devices featuring narrowband laser emission in ultrasmall volumes operating in a technologically relevant spectral range.

Active Individual Nanoresonators Optimized for Lasing and Spasing Operation

“…A more accurate description was achieved with frequency-domain FDTD simulations by incorporating the local E -field-dependent absorption at the pump wavelength and the inhomogeneous gain distribution at the probe wavelength as well [ 20 ]. The possibility of lasing improvement by plasmonically enhancing the pump phenomenon was also demonstrated [ 21 ].…”

“…Even more accurate realistic description was achieved with frequency-domain FDTD simulations by taking into account the attenuation of the pump intensity, namely by incorporating the local field dependent absorptance at the pump wavelength and the inhomogeneous gain distribution at the probe wavelength as well [20]. The possibility of lasing improvement by plasmonically enhancing the pump phenomenon was also demonstrated [21]. A novel spasing phenomenon was discovered, where the plasmonic modes are involved into stimulated emission.…”