Fiber-coupled two-dimensional photonic crystal resonators

Abstract

The subject of this thesis is about coupling between the microfiber and photonic crystal resonators. This study was started by the motivation how we can efficiently extract (or inject) the light from (into) the photonic crystal resonator. A photonic crystal (PhC) is formed by arranging the period dielectric media, where the periodicity is on the scale of an optical wavelength. It has been known as one of the platforms that can enable the miniaturization of photonic devices and their large-scale integration. By the small size of the resonator, the efficient coupling with photonic crystal resonators has been hard works because of the emission divergence from diffraction principle. Among many coupling techniques, the direct evanescent-coupling with the microfiber is considered to be suitable with many applications for a single isolated device because of its negligible propagation loss and direct interconnection with external optical systems. Especially, we have been focused on the curved microfiber. Usually, the straight microfiber has been a familiar tool to couple with the microcavities, such as microdiskes and toroid microcavities. However, the in-plane structure of 2D photonic crystal slab resonator is not fitted to use it directly because of the significant scattering between the photonic crystal pattern and the evanescent field of the microfiber. For that reason, we suggest and propose to employ the curved microfiber which provides a point contact on the 2D slab resonator in an ideal case. First, the thesis is started from the coupling mechanism between the curved microfiber and the photonic crystal resonator in Chap. 2. This chapter will cover the scattering loss (Sec. 2.1.2), the higher modes in the microfiber (Sec. 2.1.2), and the fabrication and setup of the curved microfiber (Sec. 2.1.3). After checking all possible conditions, the investigation for optimizing the coupling between the 2D photonic crystal slab resonator and the curved microfiber is co...