Wavelength Swept Photonic Crystal Laser

Abstract

Photonics has become integral to society, based on its ability to sense the environment, to manipulate materials and to transport information. The dominance of silicon electronics has made silicon photonics a compelling vision, but difficulties with light emission have caused delays in implementation and an enduring role for III-V materials. The research conducted in this Ph.D. thesis involves study and utilisation of a combination of the optical gain of Indium Phosphide with the precision and energy of silicon nanophotonics in a novel family of lasers. A continuously tunable akinetic reflective filter is exploited to obtain a wavelength swept laser. The akinetic reflective filter comprises a 2D silicon photonic crystal cavity providing wavelength selectivity at the resonance wavelength realised by means of lithographically controlled design. At the resonance wavelength, the photonic crystal cavity provides narrowband reflectance which acts as the output coupler of an external cavity laser. The reflectance band is tuned by the thermo-optic effect in silicon in order to sweep the lasing wavelength and allowing for laser frequency modulation. Two laser configurations are examined, namely: a short cavity single mode laser and a long cavity multimode Fourier Domain Mode Locked laser. The characteristics of these lasers are examined and the effects of tuning the novel photonic crystal resonant reflector in both laser configurations are explored.