Anti-resonant reflecting optical waveguides (ARROW) inscribed by the femtosecond direct-write technique

A photonic bandgap is a property of some 2D and 3D periodic dielectric structures, where light of certain frequencies is forbidden to propagate. In the form of an optical fibre, such bandgaps can be created by either surrounding a hollow core with a periodic array of air holes or alternatively in the case of a solid core by surrounding it with an array of high index inclusions. In the latter case the guiding properties can by described by the anti-resonant reflecting optical waveguide (ARROW) mechanism [1,2] with light either leaking out of the core if it is in resonance with the high index inclusions or reflecting back into the core in the case of anti-resonance. In this guiding regime the photonic bandgaps are defined by the index contrast and size of the inclusions rather than the lattice constant. Furthermore, these structures exhibit a strong wavelength dependent group velocity dispersion with one zero-dispersion wavelength in each transmission window [3]. This circumstance has been exploited for observing nonlinear propagation effects such as supercontiuum generation [4] and soliton propagation [5].