Active photonic crystal structures based on zero-dimensional active materials

Abstract

The generation of coherent light field and its interplay with a matter are key issues in quantum optics and nanophotonics. When the system is implemented in such a small dimension as the cubic-wavelength-sized scale, its dynamic process strongly reflects the nature of a quantum system and provides an indispensable way to study the nonclassical properties of light and its interaction with a matter. This thesis reports the experimental efforts to construct the high-$Q$ photonic-crystal (PC) nanocavities, which localize light in the mode volume of cubic wavelengths, based on zero-dimensional active materials that confine an electron or single electron-hole pairs. We start by describing the properties of PC structures based on erbium-doped silicon-based materials (Er-doped Si``s). The extremely slow core-level transition of Er$^{3+}$ in Si-based photonic crystals was found to be insensitive to any nonradiative processes at the surface. A clear enhancement of Er$^{3+}$ transition was demonstrated by a modification of local density of states with thin films of various refractive indices. Both observations suggest the feasibility of achieving a large Purcell enhancement. However, a relative low refractive index is an impediment to be resolved for a PC nanocavity as well as a band gap itself. The high-$Q$ PC nanocavities with an atom-like active material was realized based on indium-gallium-arsenide quantum dots (InGaAs QDs). In this system, the large material gain of InGaAs QDs and Purcell enhancement can lead to the advent of a thresholdless laser and a high bit-rate single-photon source. Major concerns were to establish a reliable scheme to fabricate high-$Q$ PC nanocavities and to characterize them in comparision with numerical calculations. The laser-like oscillation in a PC stick resonator, which allows as small mode volume as a PC unit-cell resonator does, demonstrates the possibility of a room-temperature lasing operation in the mesoscopic level of $\si...