READ ME File For 'Data set for: Kilowatt average power single-mode laser light transmission over kilometre-scale hollow core fibre' Dataset DOI: 10.5258/SOTON/D2154 Date that the file was created: March, 2022 ------------------- GENERAL INFORMATION ------------------- ReadMe Author: Hans Christian Hansen Mulvad, University of Southampton Date of data collection: 2018-2022 Information about geographic location of data collection: University of Southampton, U.K. Related projects: Programme Grant ‘Airguide Photonics’ (EPSRC) -------------------------- SHARING/ACCESS INFORMATION -------------------------- Licenses/restrictions placed on the data, or limitations of reuse: Recommended citation for the data: This dataset supports the publication: AUTHORS: H. C. H. Mulvad, S. Abokhamis Mousavi, V. Zuba, L. Xu, H. Sakr, T. D. Bradley, J. R. Hayes, G. T. Jasion, E. Numkam Fokoua, A. Taranta, S.-U. Alam, D. J. Richardson, F. Poletti TITLE: Kilowatt average power single-mode laser light transmission over kilometre-scale hollow core fibre JOURNAL: Nature Photonics (accepted for publication) PAPER DOI IF KNOWN: -------------------- DATA & FILE OVERVIEW -------------------- This dataset contains: Data files for Figure 1, 2, 3 and 4 in the main article and for Supplementary Figure 1, 2, 3 and 4 in the Supplementary Information. The corresponding figure legends are included below the file names. Figure1.xslx Fig. 1. Characterisation of the 1-km NANF. a Scanning electron microscope image of the fibre cross-section. b Measured and simulated propagation loss (left axis), simulated chromatic dispersion (right axis). c M2 (beam quality) measurement at 1064nm. d Near-field camera image of the NANF output beam at 1064nm (horizontal and vertical cross sections through the beam centre are plotted with white lines). Figure2.xslx Fig. 2. Demonstration of 1-kW power delivery over the 1-km NANF. a Experimental setup. Abbreviations: CW: continuous wave 1075-nm laser source, SCF: cabled solid-core delivery fibre, BDO: beam delivery optic, f1, f2: plano-convex lenses, f3: double-convex lens, W1, W2, W3, W4: fused silica wedges, PM: power-meter, ND: neutral density filter, x20: microscope objective with x20 magnification, CAM: camera. b photo of the 1-km NANF. c Thermal camera image of the beginning of the coated NANF fibre following the stripped input section at Pin = 1.38 kW. d Near-field camera images (CAM) of the 1-km NANF output beam at three output power levels (Pout = 27 W, 174 W and 1086 W). Figure3.xslx Fig. 3. Power delivery performance of the 1-km NANF. a Left axis: NANF output power (Pout) vs NANF input power (Pin). Right axis: throughput efficiency (TE=Pout/Pin). Note, the step-like increases in TE occur when applying the thermal lensing compensation method. b Experimentally measured input and output spectra at Pin = 218 W (Pout = 174 W) and Pin = 1377 W (Pout = 1086 W). c Simulated output spectra, based on the same experimentally measured input spectra and Pin values as shown in b (plotted also in c for reference). Figure4.xslx Fig. 4. Scalability of near-diffraction-limited CW power delivery in optical fibres at 1 µm, limited by stimulated Raman scattering (SRS). The solid lines show the maximum fibre length vs target output power achievable for a standard, commercial step-index silica SMF, a large core-area silica PCF, and an air-filled NANF. Simulations were used to calculate the SRS-induced spectral broadening in both the silica PCF and the air-filled NANF, and the diagonal lines indicate the power-distance combination at which half the power is spectrally downshifted outside the original launch signal bandwidth by SRS. The line for the silica SMF was calculated from the standard approximation for the SRS critical power (see Methods). For a NANF with an empty core (vacuum NANF), no nonlinear limitations were observed in the simulated input power range up to 11 kW, meaning the deliverable output power is only limited by fibre loss. Experimental demonstrations of power delivery including this work are denoted in the figure: silica core fibres (solid circles) and hollow-core fibres (open circles). SupplementaryFigure1.xslx Supplementary Fig. 1 | Bend loss of the 1-km NANF. a Simulated macro-bending loss at 1075 nm vs bend radius Rb, showing the maximum and minimum loss vs the bend direction (angle of bend plane vs the fibre rotation). b Effect of a single 180° bend on the transmission spectrum of the 1-km NANF (experimental data). The bend is located ~300m after the NANF input. The bend direction is not controlled. SupplementaryFigure2.xslx Supplementary Fig. 2 | Simulated spectra vs distance for single-mode CW power delivery in NANF vs silica PCF. For both fibre types, the spectra are calculated for input powers of Pin = 1.4, 2.2, 4, 7.9 and 11 kW as indicated in the left column. Note that the range of distances shown differs between the plots, as the spectral broadening vs distance depends strongly on the fibre type and input power. SupplementaryFigure3.xslx Supplementary Fig. 3 | Simulations of single-mode CW power delivery in silica PCF and NANF: spectral broadening vs distance for various input powers (PCF: dashed lines, NANF: solid lines). The spectral broadening is calculated as a 1/ρ-1, where ρ is a power spectrum overlap ratio – see Methods. The maximum tolerated spectral broadening is set to a value of 1 (ρ=0.5), indicated by the horizontal dotted line. The silica PCF simulations show good correspondence with the demonstrations reported in refs1,6 as indicated by stars in the figure. Note: the power-distance product for the reported PCF (300 kWm) is slightly lower compared to the full potential of the PCF (420 kWm) which is used in our simulations. SupplementaryFigure4.xslx Supplementary Fig. 4 | Power delivery performance for 10-m and 415-m samples of NANF-2 (propagation loss 0.55 dB/km at 1075 nm). Left axis: Output power (Pout) vs input power (Pin). Right axis: throughput efficiency (Pout/Pin).