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

Towards manufacture of ultralow loss hollow core photonic bandgap fiber

Hollow core photonic bandgap fibers (HC-PBGFs) are a class of optical fibers which guide light in a low index core region surrounded by a triangular lattice of air holes separated by a delicate silica web. The precise nature of this cladding structure requires extremely fine control of the fabrication parameters. While HC-PBGFs have found wide range of exciting research applications the initially anticipated potential for ultralow loss below that of single mode fiber (SMF) has yet to be realized. To date loss figures as low as 1.7 dB/km have been reported, however surface roughness at the core cladding interface limited further loss reduction. The loss of HC-PBGFs can potentially be decreased further by increasing the core dimensions and through optimisation of the fabrication process. To date, the manufacture of HC-PBGFs is reliant upon the two stage stack and draw process. To target ultralow loss below what has been reported to date it has become necessary to ensure repeatability and uniformity in the labor intensive stack and draw process. Repeatability is ensured through rigorous cleanliness throughout preform preparation and by precise fabrication control at each stage of manufacture. Figure 1. a) Scanning electron micrograph of a 19 cell core defect HC-PBGF, b) Attenuation scaling of the photonic bandgap (PBG) versus central guidance wavelength of 19 cell core defect HC-PBGF.Greater than 1 km lengths of HC-PBGF (Fig. 1a) can now be drawn with typical attenuations of the order of 2-3 dB/km and with significantly improved optical bandwidth (~ 100 nm) compared with previously reported. These developments open up HC-PBGF for a range of applications such as telecommunications, laser power delivery, gas sensing and strong light matter interactions, for which they have a clear advantage over conventional fibers. The attenuation scaling of the photonic bandgap (PBG) (solid curves) with central operating wavelength has been investigated in 19 cell core defect fibres (Fig. 1b). The expected attenuation proportional to lambda[-3] relationship (dashed red curve) is observed until the infrared absorption edge of silica (black dot dash curve) is breached and the attenuation increases (green curve). Through strategic fabrication improvements we have achieved repeatable low loss manufacture of HC-PBGFs. Future developments in fabrication control and fiber design will allow the realization of ultralow loss HC-PBGF

Hollow core photonic bandgap fibers for mid-IR applications

We review our fabrication of low loss (50dB/km at 3.3µm) and low bend sensitivity HC-PBGFs for mid-IR operation. Gas sensing applications are highlighted by a high resolution methane spectrum recorded in 1.26m of gas-filled fibe

Hollow core fibre technology for data transmission

We review our recent progress in developing hollow core photonic bandgap fibers for high capacity data transmission. Novel numerical and characterization tools developed to improve fiber performance and yield will be discussed

First Demonstration of a Broadband 37-cell Hollow Core Photonic Bandgap Fiber and Its Application to High Capacity Mode Division Multiplexing

We report fabrication of the first low-loss, broadband 37-cell photonic bandgap fiber. Exploiting absence of surface modes and low cross-talk in the fiber we demonstrate mode division multiplexing over three modes with record transmission capacity

Analysis and comparison of intermodal coupling coefficient of standard and hollow core few moded fibres

We compare for the first time the intermodal coupling coefficient of conventional few-moded solid fibres and of hollow-core photonic bandgap fibres and analyse its main contributions. We show that loss reduction in HC-PBGFs also results in reduced coupling coefficients

Wide-bandwidth low-loss 19-cell hollow core photonic band gap fiber and its potential for low latency data transmission

A record low loss (3.5dB/km) for a wide operating bandwidth HC-PBGF is reported. Detailed time-of-flight measurements are also presented, enabling first measurements of latency and differential group delay between mode groups in HC-PBGF

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

Measuring the group velocity dispersion of higher order modes in hollow core photonic bandgap fibre

We present for the first time the group velocity dispersion of multiple distinguishable modes propagating in 3, 7 and 19 cell hollow core photonic bandgap fibres. Measurements are made by direct phase extraction from spectral domain low coherence interferometry

3D-printed polymer antiresonant waveguides for short-reach terahertz applications

In this work, we present a 3D-printed waveguide that provides effective electromagnetic guidance in the THz regime. The waveguide is printed using low-cost polycarbonate and a conventional fused deposition modeling printer. Light guidance in the hollow core is achieved through antiresonance, and it improves the energy effectively transported to the receiver compared to free space propagation. Our demonstration adds to the field of 3D-printed terahertz components, providing a low-cost way of guiding terahertz radiation.</p