Year: 2024
Type: dissertation
Abstract: Metasurface which is made up of an array of sub-wavelength meta-atoms on a flat substrate is powerful of engineering light beam’s amplitude, phase, polarization, and frequency. It attracts increasing attentions in optical manipulation, communication, imaging, and metrology fields. To boost the metasurface’s applications in classical regime, the working principle, general design process, and fabrication flow of an all-dielectric metasurface are firstly studied in this thesis. Three working regimes of the metasurface are clearly classified. Except for the two conventional working regimes (polarization-independent regime and classical spin-multiplexing regime), a non-classical spin-multiplexing regime is explored to achieve multifunctional imaging system via a low refraction index metalens. In polarization-independent working regime, a near infrared (NIR) metalens is achieved to levitate and trap a nanorod in a vacuum. In experiment, both the translation and rotation motion of levitated nanorod can be precisely controlled by the laser beam’s polarization and power as well as the vacuum pressure. To construct an optically coupled dynamics system, a NIR dual foci metalens is achieved in the classical spin-multiplexing working regime for levitating two particles. Experiment results illustrate that the two optical potential wells can be precisely tuned, and two nanoparticles can be stably levitated at a close distance. Based on above experimental results, the world first prototype of metalens-based levitated optomechanical sensor is invented. In classical spin-multiplexing working regime, two dual-mode microscopes with a high magnification of 58X, a 600μm × 800μm field of view (FOV), and a diffraction-limited resolution are obtained via a NIR metalens where the focal point can be tuned to vortex ring from a Gaussian spot. In addition, a unified design frame is proposed to polarization-controlled generate arbitrary vector vortex beams on a HOPS and a HyOPS. In the proof of concept experiment in NIR, non-focused and tightly focused 5th order HOPS beams are firstly demonstrated. Then, tightly focused 0-1-order and 0-2-order HyOPS beams are controlled generated to comparatively study the focusing property of integer-order and fractional-order vector vortex beams. In non-classical spin-multiplexing working regime, it is the world first to achieve tri-foci metalens based on low-refraction-index material (i.e., Si3N4). An infinity-corrected microscope with three large magnifications and resolutions is firstly integrated into a centimetre-scale device via a longitudinal tri-foci Si3N4 metalens. Then, a compact simultaneously achiral and chiral microscope with a magnification of 53X is experimentally demonstrated to realize all-optics fast identification of biological and chemical sample’s chirality via a lateral Si3N4 tri-foci metalens.
Author: Sun, Chuang
Institution: University of Southampton
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6979836626