Optical dielectric nanoantenna for quantum cascade laser device directive emission

Abstract

This thesis presents the concept and modeling of a dielectric-patterned nanoantenna integrated with a quantum cascade laser (QCL) device to tailor the radiation beam and provide directive emission characteristic. A periodic dielectric configuration with optimized and different periodicities in transverse and propagating directions is realized to engineer a band-edge dispersion diagram and manipulate the performance of the source radiation. The structure is integrated with the QCL device. Directive emission of 20 dB with vertical and horizontal narrow beamwidthes of 14 degrees and 12 degrees, respectively, are demonstrated. This will be about a 2.5-times improvement in the vertical and 4.5 times-improvement in the horizontal planes of the QCL source beamwidth, offering enhanced directivity. High-efficiency power output is also obtained. Full wave analysis based on finite difference time domain (FDTD) technique is applied to characterize the device comprehensively and exploit novel physical parameters. The concept of a periodic-pattern dielectric nanoantenna is very general and can be applied in THz, IR, and visible spectrums, scaling the geometry accordingly. The obtained nanoantenna can offer optical devices directive emission, enabling long-range energy communication.