Low-loss single-mode performance in anti resonant hollow-core fibers

All data for the results of publication1. Fibre attenuations measurement The fibre attenuations were measured by the cutback measurement. A tungsten lamp was used as the light source. A short piece of single-mode optical fibre (SMF28, less than 0.5 m) was used to couple light from the light source into hollow core fibres (HCFs). A optical spectrum analyser (ANDO aq-6315b) was used to record the spectra before and after the cut-back. The coupling between SMF28 and light source was free space. The other end of SMF28 approached to HCF as close as possible. The near field patten of output of HCF was monitored by a CCD camera (DMK 41BU02). While moving SMF28 across HCF end, the output mode pattern changed with the intensity. When the output pattern became most fundamental-mode like with the highest intensity, SMF28 was fixed in place through the cutback measurement. 2. Mode excitation The mode excitation in HCFs was recorded by CCD camera while 2D scanning the butt-coupling between SMF28 and HCFs as described in 1. Fibre attenuation measurement. 3. S2 measurement S2 measurement in the manuscript adopted the same methodology described in J. W. Nicholson, A. D. Yablon, S. Ramachandran, and S. Ghalmi, "Spatially and spectrally resolved imaging of modal content in large-mode-area fibers," Opt. Express 16, 7233-7243 (2008). A home-made supercontinuum light source was used as the whitelight source. YOKOGAWA AQ6370D optical spectrum analyser was used to record the spectral fringes. LABVIEW program controlled the XY stage at the imaging plane of HCF output. The XY stage was made by two translation stages PI M-126.DG1 and THORLABS ZST