Yuvarlak silisyum mikroçınlaçlarda elastik ışık saçılması ve optoelektronik yanıtı

We review the microsphere optical resonators with their whispering gallery modes (WGM) and the coupling of light to the microspheres by optical fiber half couplers (OFHC). A theoretical background for the optical resonances in spherical particles is given for plane wave excitation using the Lorenz-Mie Theory, and Gaussian beam excitation using the Generalized Lorenz-Mie Theory (GLMT). Numerical simulations for plane wave excitation using LMT and Gaussian beam excitation using GLMT are obtained to explain the experimental light scattering results. A brief description of the experimental light scattering setup is given together with the properties of the silicon microsphere. The elastic light scattering and the observation of the WGMs on the silicon microspheres are presented for 0o transmission and 90o elastic scattering. The mode structure is analyzed with the mode spacing and quality factor measurements, which corresponds well with the theoretical expectations. The analysis of the WGM spectrum continues with the characterization of the WGM clusters. These clusters can either be explained by the angular distribution of the WGMs, azimuthal mode splitting due to ellipticity or the mode splitting induced by a particle. The observed asymmetrical lineshapes in the spectra are also explained. The presented measurements show a Fano type lineshape for the 90o elastic light scattering. This line shape is explained by the phase relation of the WGMs with the background created by the surface imperfections and the glare spots. The Fano lineshape observed in the measurements can be used for fast switching and filtering applications. A biosensing scheme for DNA particles is also presented, where a particle adsorbed on the microsphere creates an observable shift in the WGM spectrum. All in all, the optical resonances, namely WGMs are characterized towards possible applications in sizing, sensing and filtering applications. The silicon microsphere is a promising candidate for various novel photonic applications.