READ ME File For Dataset for 'Finesse Limits in Hollow Core Fiber based Fabry-Perot interferometers ' published on IEEE Journal of Lightwave Technology, vol. 39, no. 13, pp. 4489-4495, July1, 2021, doi: 10.1109/JLT.2021.3074140. Dataset DOI: 10.5258/SOTON/D1800 ReadMe Author: Meng Ding, University of Southampton This dataset supports the publication: Meng Ding, E.R. NUMKAM FOKOUA, T.D. BRADLEY, F. POLETTI, D.J. RICHARDSON, and R. SLAVIK, "Finesse Limits in Hollow Core Fiber based Fabry-Perot interferometers," in Journal of Lightwave Technology, vol. 39, no. 13, pp. 4489-4495, July1, 2021, doi: 10.1109/JLT.2021.3074140. Uploaded Archive (RAR) includes 6 data files that are Excel format (.xlsx) The figures are as follows: Fig. 2: Finesse versus mirror tilt angle, for different values of gap between the HCF end-facet and the mirror (0 um, column B; 2um, column C; 6 um, column D; 10 um, column E) Insertion loss versus mirror tilt angle, for different values of gap between the HCF end-facet and the mirror (0 um, column F; 2um, column G; 6 um, column H; 10 um, column I) Fig. 3: Finesse (column B) and Insertion loss (column C) versus cleave angle of the HCF ends. Fig. 4: Finesse versus HCF length for three values of the HCF loss ( 0.28 dB/km, column B;0.65 dB/km, column C; 1.3 dB/km, column D); Insertion loss versus HCF length for three values of the HCF loss ( 0.28 dB/km, column E;0.65 dB/km, column F; 1.3 dB/km, column G); delta_nu versus HCF length for three values of the HCF loss ( 0.28 dB/km, column H;0.65 dB/km, column I; 1.3 dB/km, column J); Q value versus HCF length for three values of the HCF loss ( 0.28 dB/km, column K;0.65 dB/km, column L; 1.3 dB/km, column M); Fig. 6: RF spectra measured with the shortest (0.65 m, column A,B) and longest (9.25 m, column C,D) HCF-FP. Fig.7: Measured values of HCF-FPs with different lengths: Finesse, column B; Insertion loss, column C; delta_nu, column D; Q value, column E; Fig. 8: Transmission spectrum of the 9.25 m HCF-FP (column C) and through HCF only (by removing the two mirrors, column B) measured by OSA with 0.02 nm resolution; Fourier transform of normalised transmission spectrum (HCF-FP, column F; No mirror, column E). Date of data collection: 1/10/2019-18/1/2020 Information about geographic location of data collection: University of Southampton, U.K. Licence: Creative Commons Attribution. Related projects: Airguide, RAEng Senior Research Fellowship, Lightpipe Date that the file was created: 8 Apirl, 2021