Enhancement of UV-visible transmission characteristics in wet-etched hollow core anti-resonant fibers

Abstract

We report on the feasibility of short-wavelength transmission window modification in anti-resonant hollow core fibers using post-processing by hydrofluoric (HF) acid etching. Direct drawing of stacked anti-resonant hollow core fibers with sub-micron thin cladding capillary membranes is technologically challenging, but so far this has been the only proven method of assuring over an octave-spanning transmission windows across the visible and UV wavelengths. In this study we revealed that low HF concentration allows us to reduce the thickness of the cladding capillary membranes from the initial 760 nm down to 180 nm in a controlled process. The glass etching rates have been established for different HF concentrations within a range non-destructive to the anti-resonant cladding structure. Etching resulted in spectral blue-shifting and broadening of anti-resonant transmission windows in all tested fiber samples with lengths between 15 cm and 75 cm. Spectrally continuous transmission, extending from around 200 nm to 650 nm was recorded in 75 cm long fibers with cladding membranes etched down to thickness of 180 nm. The experiment allowed us to verify the applicability and feasibility of controlling a silica fiber post-processing technique, aimed at broadening of anti-resonant transmission windows in hollow core fibers. A practical application of the processed fiber samples is demonstrated with their simple butt-coupling to light-emitting diodes centered at various ultraviolet wavelengths between 265 nm and 365 nm.

Microjoule‐Level Mid‐Infrared Femtosecond Pulse Generation in Hollow‐Core Fibers

“…This corrodes silica in AR‐HCF at the nanometer scale, which allows us to fine tune t with minimal impact on other geometrical parameters. [ 35 ] The fiber in Figure 6a is etched with HF solution over 15 and 38 h, which for the given concentration and flowrate, thins the wall uniformly along the fiber by 50 and 130 nm to reduce t to 1.55 and 1.47 $$\umu$$m, respectively. The magnified images of thinned walls are presented in Figure 6c.…”

2023 Astrophotonics Roadmap: pathways to realizing multi-functional integrated astrophotonic instruments

“…Although UV-transmitting fiber optics have been available for decades, future gains can be made by extending to shorter wavelengths (<200 nm), reducing transmission losses and increasing solarization resistance. Current technologies seeing continued development include transmissive step-index fiber (UV grade silica [288,289], fluoride and flurophosphate [290]) and solarization-free anti-resonant hollow core fiber technologies [291][292][293]. Photonic crystal and hollow-core fibers have also been used for the development of UV-visible photonic sources (e.g.…”