Development of erbium-doped and bismuth-doped optical fibres for wideband and high-performance amplifiers for telecommunication applications

Abstract

To support the continuously growing demand for data-carrying capacity of optical fibres in telecommunications, developing efficient fibre amplifiers for extended wavelength bands beyond traditional C- and L-bands is crucial. The O-, E-, S-bands (1260-1530 nm), and the extended L-band (1615-1625 nm), within the low-loss transmission window of standard silica fibres, hold significant research and commercial potential. Erbium (Er)-doped fibre amplifiers (EDFAs) are well-studied for the C- and L-bands, but require enhancements in gain flatness, noise, efficiency, and bandwidth extension beyond 1615 nm. Bismuth (Bi)-doped silica fibres, with their ultra-wide near-infrared (NIR) luminescence from various Bi active centres (BACs), offer promising potential for developing wideband Bi-doped fibre amplifiers (BDFAs).
In this thesis, I fabricated Er-doped fibres using the modified chemical vapour deposition (MCVD)-solution doping technique by tailoring the glass core compositions to favour L-band amplification. Fibre spectroscopic properties were characterised including refractive index profile, absorption, background loss, unsaturable loss, fluorescence, lifetime, on/off gain, and Er3+ cross-sections. Using the fabricated EDFs, I developed L-band amplifiers to achieve a high gain of ≥20 dB from 1565-1625 nm in a double-pass configuration, a flat gain ripple of ±0.7 dB from 1580-1615 nm by forming AlPO4 units in the fibre and pumped at 980 nm, an extended operating wavelength up to 1628 nm with a 13.6 dB gain by forming AlPO4 units and pumped at 1480 nm. Er/Yb co-doped fibre amplifier (EYDFA) was built up utilising 1480 nm core-pumping to shorten the L-band device length to 23 m.
High-performance BDFAs were developed using BDFs fabricated by other fabricators. Using Bi-doped germano-silicate fibres (BGSFs) and phospho-silicate fibres (BPSFs), a high gain and high gain-per-unit-length BDFA was demonstrated in the E+S band with shortened device lengths (25.5 m to 48 m), and a high-gain ultra-wideband BDFA was presented in the O+E+S band with a 140 nm 20 dB-gain bandwidth for a -23 dBm input signal, respectively. Spectroscopic properties of various BACs were analysed, and a fully integrated, compact BDFA device box was developed.
Moreover, robust amplifiers were developed to adapt to extreme temperatures and irradiation conditions. For EDFAs, a hybrid configuration was proposed to balance temperature stability and L-band gain, achieving low noise and temperature-insensitive gain flatness from 1585-1615 nm. Radiation tolerance was characterised in various core-composition EDFs after gamma-irradiation to develop radiation-resistant EDFAs in the C- or L-band using cerium (Ce) co-doping. In addition, a radiation-resistant E+S band BDFA was developed with a 35 dB post-irradiation gain.

More information

Identifiers

ORCID for Ziwei Zhai: orcid.org/0000-0001-7128-7326

ORCID for Jayanta Sahu: orcid.org/0000-0003-3560-6152

ORCID for Johan Nilsson: orcid.org/0000-0003-1691-7959

Catalogue record

Export record