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

Dual hollow-core anti-resonant fibres

While hollow core-photonic crystal fibres are now a well-established fibre technology, the majority of work on these speciality fibres has been on designs with a single core for optical guidance. In this paper we present the first dual hollow-core anti-resonant fibres (DHC-ARFs). The fibres have high structural uniformity and low loss (minimum loss of 0.5 dB/m in the low loss guidance window) and demonstrate regimes of both inter-core coupling and zero coupling, dependent on the wavelength of operation, input polarisation, core separation and bend radius. In a DHC-ARF with a core separation of 4.3 µm, we find that with an optimised input polarisation up to 65% of the light guided in the launch core can be coupled into the second core, opening up applications in power delivery, gas sensing and quantum optics

Modal content in hypocycloid Kagomé hollow core photonic crystal fibers

The modal content of 7 and 19 cell Kagomé anti resonant hollow core fibers (K-ARF) with hypocycloid core surrounds is experimentally investigated through the spectral and spatial (S2) imaging technique. It is observed that the 7 and 19 cell K-ARF reported here, support 4 and 7 LP mode groups respectively, however the observation that K-ARF support few mode groups is likely to be ubiquitous to 7 and 19 cell K-ARFs. The transmission loss of the higher order modes (HOMs) was measured via S2 and a cutback method. In the 7 cell K-ARF it is found that the LP11 and LP21 modes have approximately 3.6 and 5.7 times the loss of the fundamental mode (FM), respectively. In the 19 cell it is found that the LP11 mode has approximately 2.57 times the loss of the FM, while the LP02 mode has approximately 2.62 times the loss of the FM. Additionally, bend loss in these fibers is studied for the first time using S2 to reveal the effect of bend on modal content. Our measurements demonstrate that K-ARFs support a few mode groups and indicate that the differential loss of the HOMs is not substantially higher than that of the FM, and that bending the fiber does not induce significant inter modal coupling. A study of three different input beam coupling configurations demonstrates increased HOM excitation at output and a non-Gaussian profile of the output beam if poor mode field matching is achieved

Recent advances in hollow fiber technology for telecoms applications

We review our recent work on the modelling, fabrication and characterization of hollow-core photonic bandgap fibers. We discuss the modal content of these fibers, as well as the opportunities and challenges presented by modal interactions in space division multiplexed transmission applications

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

S2 measurement of higher order mode content in low loss hypocycloid Kagomé hollow core photonic crystal fiber

We present the first detailed investigation of modal properties in hypocycloid Kagomé fibers; even with an optimized input launch, higher order modes propagate over long fiber lengths, indicative that these modes have low attenuation

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

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

We report an effectively singlemode tubular antiresonant hollow core fiber with >1000nm bandwidth and record-low loss of 25dB/km, fully connectorizable with SMF28. We demonstrate penalty-free data transmission at wavelengths of 1065, 1565 and 1963nm

High capacity, low latency data transmission using hollow core photonic bandgap fibers

We discuss our recent progress in hollow core-photonic bandgap fiber fabrication for high capacity transmission, focusing on two key areas: longitudinal uniformity and length upscaling as well as reviewing highlight results in data transmission