Hollow antiresonant fibers

While working at the University of Bath in the United Kingdom, I have pioneered radically novel structures of hollow core optical fibers which received lately a great interest by the scientific community. I worked as a postdoctoral research associate within the project  "New Fibers for new lasers: photonic crystal fibre optics for the delivery of high-power light” funded by the EPSRC (EP/I011315/1). You can find here a key presentation made on this project in December 2013 (Link). 
Moreover this timeline resumes some of my most important and influential results during that time.


[1] In September 2013 my first paper on the topic of hollow antiresonant fibers (ARFs) is published. I study the impact of the curvature of the internal core boundary on the guidance properties of ARFs. The numerical studies bring to a better inside into the properties of this fibre type and constitute the theoretical basis for the future development of novel geometrical  structures. 
W. Belardi and J. C. Knight, "Effect of core boundary curvature on the confinement losses of hollow antiresonant  fibers," Opt. Express 21, 21912-21917 (2013).Link

[2] The 13th March 2014 I present in San Francisco my novel idea for an hollow core ARF with very low losses, possibly even below those of hollow core Photonic Bandgap Fibers. I prove the feasibility of this fiber type by showing some pictures of the first fabricated fibers of this type.
W. Belardi and J. C. Knight, "Negative curvature fibers with reduced leakage loss," OFC 2014, San Francisco 9-13 Mars 2014. (Supplementary material).Link Suppl Mat

[3] On the 1st April the details of my idea for reducing the attenuation of hollow core optical fibers are published on the Optics Letters Journal. The idea is based on the use of a nested ring design.  
W. Belardi and J. C. Knight, "Hollow antiresonant fibers with reduced attenuation"  Opt. Letters 39, 1853-1856 (2014).Link

[4] At the end of April a new breakthrough paper is published.My numerical studies show that ARFs with very large core sizes, extended bandwidth and low bending loss in the mid-infrared CAN be realized. I prove that by fabricating the first ARFs with low bending losses in the Mid-Infrared.
W. Belardi and J. C. Knight, "Hollow antiresonant fibers with low bending loss," Opt. Express 22, 10091-10096 (2014).Link


[5] I fabricate an ARF with low bending loss optimized for guidance at 3.5microns. Sam Bateman uses this fibre (by filling it with Helium-Xenon) in order to demonstrate the first light generation through gas discharges at this wavelength. This work is accepted as a postedeadline paper at the CLEO conference held in San Jose, on the 12th June. 
S. Bateman, W. Belardi, F. Yu, C. Webb, W. J. Wadsworth “Gain from Helium-Xenon Discharges in Hollow Optical Fibres at 3 to 3.5 ┬Ám”, CLEO 2014 San Jose 8-13 June 2014 (postdeadline session)  Link

[6] The fibres I have fabricated with low bending losses show another big advantage. They not simply have very low bending loss but present the characteristic of having low losses at multiple antiresonant windows. My colleague Zefeng Wang adopts this property in order to demontrate light generation at 3.1microns through optical pumping at 1.5microns, in one of my fibres filled with acetylene.
Z. Wang, W. Belardi, F. Yu,  W. J. Wadsworth, and J. C. Knight “Efficient diode-pumped mid-infrared emission from acetylene-filled hollow-core fiber”, Opt. Express 2014, Vol. 22 (8) pp. 21872-21878 Link