Cao, Victoria; (2024) Advanced O-Band III-V Quantum-Dot Based Semiconductor Optical Amplifiers. Doctoral thesis (Ph.D), UCL (University College London).

Text Victoria Ya_Cao_PhD Thesis_Victoria Cao.pdf - Accepted Version Download (10MB)

Abstract

Semiconductor optical amplifiers (SOAs) based on advanced quantum dot (QD) technology have emerged as promising building blocks to reconstitute the attenuated signals in photonic integrated chips, enabling high-speed short-reach optical communication. The unique carrier confinement of QD nanostructures and state-ofthe-art epitaxial growth method have granted SOAs attractive features such as broadband gain, high saturation power, low noise figure, ultra-fast gain recovery, high temperature operation, and monolithic integration opportunities. Driven by the advantages of QD nanostructures, this thesis focuses on designing, fabricating, and characterising high-performance QD-based SOAs operating in the O-band. Owing to the high degree of optimisation in device structural design, ridge waveguide fabrication process, and packaging scheme, as well as developing advanced device characterisation system, QD SOAs with impressive static characteristics have been demonstrated in Chapter 3, including a high on-chip gain of 32.4 dB, a high saturation output power (SOP) of 12.2 dBm, and a low noise figure (NF) below 5 dB. A comparative study of various ridge waveguide geometries and a thorough investigation of the operating parameters have been conducted to comprehensively understand devices’ characteristics. Based on this work, distortion-free amplification of optical frequency comb with an ultra-high repetition rate of 100 GHz and ultrashort pulse width of 1.8 ps was presented in Chapter 4. Remarkably, this comb signal amplified by the QD SOA achieved high-speed error-free transmission of up to 80 Gbaud non-return-to-zero signal under a high repetition rate of ~100 GHz and outperformed the commercial O-band optical amplifier. The final chapter of the thesis introduces a novel chirped QD structure design that extends the SOA’s 3-dB gain bandwidth from 20 nm to 50 nm. Furthermore, a bi-directionally operated QD SOA utilising dual ground state emission spectrum has been demonstrated for the first time, enabling a 10 dB receiver sensitivity improvement in the ultra-high-speed data transmission system.

Download activity - last month

Export as CSVXMLJSON

Download activity - last 12 months

Export as JSONXMLCSV

Downloads by country - last 12 months

Export as CSVXMLJSON

Archive Staff Only

View Item