Understanding wavelength scaling in 19-cell core hollow-core photonic bandgap fibers

First experimental wavelength scaling in 19-cell core HC-PBGF indicates that the minimum loss waveband occurs at longer wavelengths than previously predicted. Record low loss (2.5dB/km) fibers operating around 2µm and gas-purging experiments are also reported

Mitigating spectral leakage and sampling errors in spatial and spectral (S2) imaging

We present a novel method for validating the relative power value (MPI) of the Spatial and Spectral (S2) imaging technique. By applying corrections for spectral leakage and sampling errors we found the MPI determinations to be accurate within 1dB

Accurate loss and surface mode modeling in fabricated hollow-core photonic bandgap fibers

We present a method to reconstruct the cross-sectional profile of fabricated hollow-core photonic bandgap fibers from SEM images. For the first time, numerical simulations show a good agreement with measured loss and surface mode position

Inspection of defect-induced mode coupling in hollow-core photonic bandgap fibers using time-of-flight

We analyze defect-induced mode coupling in a hollow-core photonic bandgap fiber using time-of-flight, and show its utility in complementing optical time-domain reflectometry

Antiresonant hollow core fiber with an octave spanning bandwidth for short haul data communications

We report an effectively single mode tubular antiresonant hollow core fiber with minimum loss of ~25 dB/km at ~1200 nm, and an extremely wide low loss transmission window (lower than 30 dB/km loss from 1000 nm to 1400 nm and 6 dB bandwidth exceeding 1000 nm). Despite the relatively large mode field diameter of 32 µm, the fiber can be interfaced to SMF28 to produce fully connectorized samples. Exploiting an excellent modal purity arising from large modal differential loss and low intermodal coupling, we demonstrate penalty-free 10G on-off keying data transmission through 100m of fiber, at wavelengths of 1065, 1565 and 1963nm

Surface plasmon in slab waveguide: a verification test-bed

Since its first use in a real-time analysis of a biological system in 1990s, surface plasmon resonance (SPR) has become an important optical biosensing technology for its real-time, label-free, and noninvasive nature. In this paper we review electromagnetic theory of surface plasmons in dielectric-metal-dielectric planar waveguides and verify capabilities of an emerging computational package, COMSOL, that uses finite element methods (FEM) for analysis of plasmonic phenomena. Results of analytical and numerical methods are compared and accuracy of FEM solver is discussed

Accurate modelling of hollow core photonic bandgap fibre

A modelling tool to accurately reproduce the performance of fabricated hollow-core photonic bandgap fibers from their SEM images is presented. This enables new understanding of the effect of cross-sectional distortions

High sensitivity gas sensing using hollow core photonic bandgap fibres designed for operation at mid-IR wavelengths

High sensitivity gas detection is of great interest in the fields of security, medical diagnostics, and environmental and industrial monitoring. Optical absorption methods are well established and the use of fibre based devices has advantages in terms of small footprint, relatively low cost, immunity to electromagnetic interference and potential for distributed sensing; however, they generally suffer from poor sensitivity due to the difficulty of achieving an efficient spatial overlap with gas analytes. The use of Hollow Core Photonic Bandgap Fibres (HC-PBGFs), i.e. a special type of optical fibres that guide light in a hollow core through bandgap effects, enables an extremely efficient sensing platform due to close to 100% overlap between the light and gas in the hollow core and the possibility for long interaction lengths. Furthermore, HC-PBGFs can be designed to operate at mid-IR wavelengths, where conventional fibres cannot operate. We recently demonstrated HC-PBGFs with loss as low as 0.05dB/m at 3.3µm and more than 100nm 3dB transmission bandwidth [1]. The capability of accessing the mid-IR wavelengths is critical for gas sensing, as the fundamental vibrational transitions of many gas molecules (for instance those containing C-H, O-H, N-H groups) fall in this spectral region. By detecting the fundamental absorption bands as opposed to their much weaker overtones in the near IR often targeted by fibre based sensor systems, substantially higher sensitivity can be achieved [2]. Additionally, mid-IR HC-PBGFs have relative large core diameters (~50 µm), which is beneficial in allowing a comparatively faster gas filling and evacuation

Real-time modal analysis via wavelength-swept spatial and spectral (S2) imaging

We present a fast implementation of the spatial and spectral imaging (S2) technique for modal analysis of multimode optical fibers. It utilizes a continuously scanning tunable laser source with an InGaAs camera operating at 500Hz along with inline data processing to increase the measurement repetition rate, by reducing the run up/run down time between two successive scans (about 27 times faster as compared to the previous state of the art). This allows real-time mode content monitoring of a multimode fiber. We illustrate the potential of this tool by collecting an 110,000 wavelength S2 spectrogram of a 5 mode-group fiber in minutes, and tracking, in real-time, the four LP11 modes of the same fiber as the launch polarization is rotated

Efficient, wide angle, structure tuned 1 x 3 photonic crystal power splitter at 1550 nm for triple play applications

We propose a wide angle, efficient and low loss 1 x 3 power splitter based on triangular lattice air holes silicon slab Photonic Crystal (PhC). Desired power splitting ratio was achieved by altering the structure at the junction area of the power splitter. Simulation results obtained using 2-D finite difference time domain method show that for TE polarization incident signal, the power is distributed almost equally with total normalized transmission of 99.74 and negligible reflection loss at the 1550 nm optical operating wavelength. In addition, the power splitter can operate at 1388 nm and 1470 nm optical wavelengths