Studies of Post-Draw Thermal and Optical Processing on Bi/Er Co-Doped Fibers

With the rapid development of optical fiber technology, fiber loss has been greatly reduced in spectral region from 1200 nm to 1700 nm. To date, only limited spectral range (approximately 100 nm or 20% of the total 500 nm band between 1200 nm and 1700 nm band) has been commercially utilized, since erbium-doped fiber amplifier (EDFA) is the only commercially available optical fiber amplifier working within 1520 nm to 1620 nm. Therefore, developing wideband and flat-gain fiber amplifiers operating the whole or the EDFA uncovered spectral region of 1200 nm to 1700 nm, has been pursuing for higher capacity photonic networks. Bismuth and Erbium co-doped Fibers (BEDFs), due to near infrared (NIR) broadband luminescence, are regarded as promising gain media towards developing wideband and flat-gain fiber amplifier covering entire range of available bands between 1200 nm and 1700 nm. There are various bismuth active centers (BACs) responsible for different NIR luminescence bands and the formation of BACs is closely correlated with fiber core compositions, fabrication, and post-draw processing. To develop efficient BEDFs lasers/amplifiers, the higher BACs concentration is needed, and high unsaturable losses needs to be further reduced. In this thesis, post-draw thermal and optical processing and effects on performance of BEDFs are studied, exploring potential post-draw processing methods to improve the BEDFs performance. The BEDFs demonstrated in this thesis were manufactured in National Fiber Facility at University of New South Wales (UNSW). Research works, outcomes and original findings from this PhD study are briefly summarized in the following. (1) Presented an overview of the development of BEDFs (2) Presented a review of the post-draw thermal and optical processing on BDFs/BEDFs (3) Studied and identified thermal effects on BAC-Si activation and background loss in BEDFs (4) Investigated and achieved BAC-Si activation on thermal quenching in BEDFs (5) Investigated and achieved loss reduction on thermal annealing in 3D silica lithography BEDFs (6) Studied and found the relation between BAC-Si photobleaching and Al2O3 doping concentrations in BEDFs (7) Studied and found the dependence of cut-off wavelength on temperature in BEDF