Gain and Noise Performance of Bi/Er Co-Doped Fibre Amplifiers

In this information era, optical communication technology is vital for telecommunications. Signal transmitted through optical medium suffers attenuation. To solve this problem, optical fibre amplifiers, which have broadband amplification, high efficiency and high gain, are applied in optical communications. The typical widely used fibre amplifier is Erbium doped fibre amplifier (EDFA), which covers 1520- 1620nm. To satisfy the increasing demands for other bands, some researches recently study the Bismuth doped fibre amplifier (BDFA), which covers 1150-1550nm. In this thesis, a new fibre amplifier, Bi/Er co-doped fibre amplifier (BEDFA) aiming to cover an ultra-broadband 1200-1600nm, is studied. Both experiment measurements and theoretical models are explored to analyse net gain and noise figure performance of BEDFAs. And the optimized design of the BEDFA with desirable net gain and noise figure are provided. Firstly, some basic experiment techniques relevant to fibre amplifiers characteristics, including emission, up-conversion emission, ground state absorption, lifetime, cross section area, net gain and noise figure are introduced. Experiments on Erbium doped fibres (EDFs) and EDFAs under 980nm pump are carried out as a practice to familiarize myself with experiment methods, and some experiment results are obtained. Secondly, the modelling of EDFA is done based on the models that are well developed from literatures. Two EDFA cases: simplified three-level system, and three-level system with Stark splitting and homogeneous broadening, are implemented as a practice to familiarize myself with modelling and implementation. In particular, I have used my experiment results of the EDFs and EDFAs to simulate the amplification performance of the EDFA in the latter case. Thirdly, homemade Bi/Er co-doped fibres (BEDFs) and BEDFAs are investigated based on the general experiment methods learned from EDFs and EDFAs. Some experiments regarding BEDFA modelling, including emission, up-conversion emission, ground state absorption, excited state absorption, cross section area, lifetime, energy transfer, net gain and noise figure, are studied to evaluate the BEDF and BEDFA. The broadband emission from 1000nm to 1700nm is observed in the BEDF, and this result shows the potential for developing BEDFAs. The experimental results of net gain and noise figure v are obtained, and they show that the homemade BEDFA under 830nm pump cannot achieve amplification at 1420nm. And the performance issues of this BEDFA are discussed. Finally, modelling and simulations are carried out to theoretically analyse BEDFAs and optimize parameters for improving BEDFA amplification performance. I theoretically study the BEDFA by building three simplified models, which include Model 1 (model without excited state absorption or energy transfer), Model 2 (model with excited state absorption), and Model 3 (model with energy transfer). The three models consider aluminium related bismuth active centres (BAC-Al), silicon related bismuth active centres (BAC-Si), and Erbium centres. And rate equations and propagation equations are established for these three models respectively. By solving these equations, the population density of each energy level, and pump power, amplified spontaneous emission (ASE) power and signal power along the fibre can be obtained. The work on three models are summarized: 1. In the case of Model 1, the net gain and noise figure of the BEDFA are simulated using parameters estimated from experiment results to assess the amplification performance of this BEDFA. As a result, possible issues of the homemade BEDFA including low BAC-Si concentration, low 1420nm emission to absorption cross section ratio and high background loss are given. Subsequently, an optimized BEDFA design, which is a 3.2m BEDFA under 100mw 830nm pump with 43.73dB net gain and 7.73dB noise figure at 1420nm, is found among eighteen typical cases. 2. In the case of Model 2, the excited state absorption is studied. I only study the BAC-Si in Model 2. I find that the excited state absorption of BAC-Si reduces amplification performance at 1420nm. 3. In the case of Model 3, the energy transfer is studied. I find that the energy transfer from Er!! to BAC-Al does not influence 1420nm amplification, but influences the emission at 1100nm and 1530nm.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2016

Author dc:creator

• Liu, Han

• Optical fibre characterizations
• Net gain
• Noise figure
• Bismuth/Erbium co-doped fibre amplifiers.
• Net gain.
• Noise figure.
• Fibre amplifier simulations.
• Optical fibre characterizations.

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/2978

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/56231