Tm3+/Ho3+ profiled co-doped core area optical fiber for emission in the range of 1.6–2.1 µm

Abstract

Double-clad optical fiber with a multi-ring core profile doped with thulium and holmium fabricated by Modified Chemical Vapor Deposition Chelate Doping Technology (MCVD-CDT) is presented. The measured Tm2O3 and Ho2O3 complexes’ weight concentrations were 0.5% and 0.2% respectively. Numerical analyses show weakly guiding conditions and 42.2 µm of MFD LP01 at 2000 nm. The low NA numerical aperture (NA = 0.054) was obtained for the 20/250 µm core/cladding ratio optical fiber construction. The emission spectra in the range of 1.6–2.1 µm vs. the fiber length are presented. The full width at half maximum (FWHM) decreases from 318 to 270 nm for fiber lengths from 2 to 10 m. The presented fiber design is of interest for the development of new construction of optical fibers operating in the eye-safe spectral range.

Broadband Profiled Eye-Safe Emission of LMA Silica Fiber Doped with Tm3+/Ho3+ Ions

“…Typically, to obtain single-mode operation for One of the constructions of LMA fibers is the multi-ring structure of the refractive index profile that allows for increasing the effective propagation area of the fundamental mode (mode field diameter) even several hundred times [45][46][47][48]. In fact, there is a compromise between the ideal shape close to the Gaussian profile of the fundamental mode in classic construction single-mode fibers and increasing the mode field diameter (MFD) using multi-ring LMA construction fibers [49][50][51][52][53]. The multi-ring structures of the core profile were historically used for bend-resistant and dispersion-shifted/flattened optical fibers [54][55][56][57].…”