Research & Applications Of Optical Microring Resonators

The field of information and communication technology (ICT) is witnessing an unprecedented development speed in history. Moore's law proves that the processor speed and memory size are merely doubling each 18 months, which is expected to continue in the next decades. If photonics is going to play a substantial role in the ICT market, it will have to follow the same dynamics. All-optical signal processing is one of the promising technologies to omit optical-electric-optical converters in future all-optical networks.Optical devices with smaller size, more simiple structure and stable performance are especially needed in all-optical signal processing. Microring resonator is an important optical device for such use, which has already been widely used in optical communication and and sensor. What's more, it also plays a key role in laser technology. Therefore, the microring resonator with a high integration has become a hot topic for researchers.In this thesis, we first introduce the principle of mcroring resonator, analysis their transmission property. Then we introduce the finite-difference time-domain (FDTD) simulation methods which are widely used in modeling large-scale photonic circuits. Finally, we focus on the fabrication and application of microring resonators beased on two kinds of materials as follows.1. Microring resonator based on Silicon-On-Insulator (SOI) Micro-ring resonators based on silicon-on-insulator (SOI) structure are promising building-blocks for ultra-compact and highly integrated photonic circuits. The fabrication technology is mostly CMOS-compatible. Potential applications include optical filtering, switching, signal processing and bio-sensing.We present a new way to improve the transmission notch depth by placing another concentric ring and generating directional coupling between the rings. The coupled modes diffuse across the rings, which may be favourable for biosensing applications as it expands the detection area. We have successfully designed and fabricated a concentric ring resonator with improved notch depth. Comparing with the conventional sigle ring resonator, this noval structure shows 10 times higher sensitivity when employed in the biosensing.2. Microfiber ring resonatorThe microfiber waveguide drawn from standard single mode optical fiber by heating has attractive advantages in cheaper expense, easier fabrication and coupling to fiber system, better smooth surface, and significant smaller loss than that fabricated lithographically. The microfiber based knot resonators show stability and good quality optical resonance.There has been an increasing research in controlling the velocity of light including fast light (velocities larger than the speed c of light in vacuum ) and slow light (velocities smaller than c). It offers the possibility of all-optical packet switched networks and optical interconnections in computer systems with optically storing and buffering optical signals. Fast light is attractive since the superluminal signal velocity can be achieved without violating Einstein causality.We report demonstration of fast light in an under coupled microfiber ring resonator with Sagnac loop. In our experiment, a maximum of ~58ps pulse advancement was achieved with apparent signal distortion for a 5-Gb/s RZ signal.