1 Low power continuous-wave nonlinear optics in silica glass integrated waveguide structures

Integrated photonic technologies are rapidly becoming an important and fundamental milestone for wideband optical telecommunications. Future optical networks have several critical requirements, including low energy consumption, high efficiency, greater bandwidth and flexibility, which must be addressed in a compact form factor (Eggleton et al., 2008; Alduino & Paniccia, 2007; Lifante, 2003). In particular, it has become well accepted that devices must possess a CMOS compatible fabrication procedure in order to exploit the large existing silicon technology in electronics (Izhaky et al., 2006; Tsybeskov et al., 2009). This would primarily serve to reduce costs by developing hybrid electro-optic technologies on-chip for ultrafast signal processing. There is still however, a growing demand to implement all-optical technologies on these chips for frequency conversion (Turner et al., 2008; Venugopal Rao et al., 2004), all-optical regeneration (Salem et al., 2008; Ta’eed et al., 2005), multiplexing and demultiplexing (Lee et al., 2008; Bergano, 2005; Ibrahim et al., 2002), as well as for routing and switching (Lee et al., 2008; Ibrahim et al., 2002). The motivation for optical technologies is primarily based on the ultrahigh bandwidth of the optical fiber and the extremely low attenuation coefficient. Coupled with minimal pulse distortion properties, such as dispersion and nonlinearities, optical fibers are the ideal transmission medium to carry information over long distances and to connect optical networks. Unfortunately, the adherence of the standard optical fiber to pulse distortions is also what renders it less than perfectly suited for most signal processing applications required in telecommunications. Bending losses become extremely high in fibers for chip-scale size devices, limiting its integrability in networks. Moreover, its weak nonlinearity limits the practical realization (i.e. low power values and short propagation lengths) of some fundamental operations requiring nonlinear optical phenomena, such as frequency conversion schemes and switching (Agrawal, 2006). Several alternative material platforms have been developed for photonic integrated circuits (Eggleton et al., 2008; Alduino & Panicia, 2007; Koch & Koren, 1991; Little & Chu, 2000), including semiconductors such as AlGaAs and silicon-on-insulator (SOI) (Lifante, 2003;