A fractal-based fibre for ultra-high throughput optical probes

A core component of all scanning near-field optical microscopy (SNOM) systems is the optical probe, which has evolved greatly but still represents the limiting component for the system. Here, we introduce a new type of optical probe, based on a Fractal Fibre which is a special class of photonic crystal fibre (PCF), to directly address the issue of increasing the optical throughput in SNOM probes. Optical measurements through the Fractal Fibre probes have shown superior power levels to that of conventional SNOM probes. The results presented in this paper suggest that a novel fibre design is critical in order to maximize the potential of the SNOM

Self-aligning method of fiber-to-waveguide pigtailing

An innovative self-aligning technique for the pigtailing of optical fibers to buried channel planar waveguides is presented, based on selective etching. This technique utilizes a plug-and-socket mechanism that is intrinsically self-aligning and mechanically stable. The processes involved have been specifically designed to facilitate the bulk manufacture of pigtailed single or multiple fibers and waveguides. An optimized alignment geometry for the physical connection of fibers to waveguides is presented.Financial support from the Australian Research Council is acknowledged

Direct measurement of core profile diffusion and ellipticity in fused-taper fiber couplers using atomic force microscopy

The geometrical shape and refractive index profile of the cores of fused-taper fibre couplers made by the heating, fusing and tapering technique have been measured to an accuracy of better than 10 nm. This approach involves precision cleaving, hydrofluoric acid etching and atomic force microscope (AFM) measurement. Results reveal that the core profile and cross-sectional geometry along the taper differ significantly from the normal assumption of scaled circular cores

Refractive index profiles of Ge-doped optical fibers with nanometer spatial resolution using atomic force microscopy

We show a quantitative connection between Refractive Index Profiles (RIP) and measurements made by an Atomic Force Microscope (AFM). Germanium doped fibers were chemically etched in hydrofluoric acid solution (HF) and the wet etching characteristics of germanium were studied using an AFM. The AFM profiles were compared to both a concentration profile of the preform determined using a Scanning Electron Microscope (SEM) and a RIP of the fiber measured using a commercial profiling instrument, and were found to be in excellent agreement. It is now possible to calculate the RIP of a germanium doped fiber directly from an AFM profile

Transition Loss in Bent Waveguides and Fibres

We determine the origin of transition loss in bent waveguides and fibres. We show that transition loss can be suppressed, even in very tight bends provided that, in the geometrical transition from the straight to the bent waveguide or fibre, the local curvature is increased sufficiently slowly along the bend. Experimental results demonstrate this effect and are shown to be consistent with numerical simulations