LMI Seminar: Optical properties and spectral shaping of lasing in vertically aligned nanowire ensembles

Abstract:

Semiconductor nanowires (SCNW) are structures with cross sectional diameter of 10-200 nm and length ranging from hundreds of nanometers to several millimeters. Vertically standing SCNW can be synthesized by top-down etching techniques or by bottom-up chemical growth methods that provide great control of material composition, nanowire dimensions, and growth location. Due to their crystalline structure and high refractive index, SCNWs provide strong optical confinement with excellent waveguiding capabilities. These features, together with their subwavelength transverse dimension, foster many intriguing optical phenomena related to manipulation, generation, amplification, guiding and detection of light. In my talk, I will review the basic optical characteristics of vertically standing SCNW, including their optical waveguiding, end facet reflection, transverse and longitudinal supported modes and lasing conditions. Then, I will present some advanced techniques for controlling SCNW lasers' spectra and achieving single mode lasing. Finally, some unique optical properties of ordered SCNW arrays will be discussed. These properties depend on the parameters of both the single nanowire and the geometry of the nanowire array, and lead to complex reflectance, strong light scattering and vivid structural colors.

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