Single-mode all-silica photonic bandgap fiber with 20-microm mode-field diameter.
Egorova ON, Semjonov SL, Kosolapov AF, Denisov AN, Pryamikov AD, Gaponov DA, Biriukov AS, Dianov EM, Salganskii MY, Khopin VF, et al. Opt Express. 2008 Aug 4; 16(16):11735-40.