Femtosecond lasers for datacommunications applications
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Date
30/11/2005Author
Supervisor
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Abstract
The work
presented in this thesis details the development of all-solid-state ultrashort pulsed
lasers suitable for datacommunications applications at either 1300nm or 1550nm. This is
achieved
through the design and construction of three different types of laser system based
on the gain materials Cr⁴⁺:forsterite (chromium-doped magnesium iron silicate) and
Cr⁴⁺:YAG (chromium-doped yttrium aluminium garnet).
A Cr⁴⁺:forsterite based system is the first laser that is presented. This configuration
utilises a
relatively novel GalnNAs semiconductor device to initiate the generation of 130fs
pulses around 1300nm. Although GalnNAs devices have previously been used to generate
pulses of light in the picosecond domain, this is the first time ultrashort pulses have been
achieved in the femtosecond domain. As such, it has been possible to use the results from
this laser system to further the understanding of various dynamics of GalnNAs devices.
An SBR mode-locked Cr⁴⁺:YAG laser system introduces the concept of
Femtosecond pulse generation around 1550nm. This is done in order to lay the necessary
foundations for understanding the motivation and physics behind high pulse repetition
frequency (prf) all-solid state femtosecond lasers suitable for datacommunications
applications. Details are then given for the construction and operation of a simple 3-element
Cr⁴⁺:YAG laser that
generates 70fs pulses at a prf greater than 4GHz. The success of this
system leads to the development of a compact and robust engineered prototype with a
footprint of 215x 106mm².
Integration of the high prf laser systems into novel optical time division
multiplexing/wavelength division multiplexing (OTDM/WDM) based assessments prove
successful with the demonstration of a datacommunications system capable of generating
1.36Tb/s. This still remains to be the only system capable of achieving such a high capacity
from a
single source and demonstrates the ongoing success of femtosecond lasers through
continued research and
development.
Type
Thesis, PhD Doctor of Philosophy
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