Fiber Bragg Grating : bimetal temperature sensor for solar panel inverters / Mohd Afiq Ismail
This thesis demonstrates various techniques for generating passive Q-switched and soliton mode-locked fiber laser using Erbium-doped fiber and Thulium-Bismuth doped fiber laser as gain mediums. The techniques for obtaining Q-switched and soliton mode-locked fiber laser includes nonlinear polariza...
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| Format: | Thesis |
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2015
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| Online Access: | http://studentsrepo.um.edu.my/8075/ http://studentsrepo.um.edu.my/8075/4/Master_copy.pdf |
| Summary: | This thesis demonstrates various techniques for generating passive Q-switched and
soliton mode-locked fiber laser using Erbium-doped fiber and Thulium-Bismuth doped fiber
laser as gain mediums. The techniques for obtaining Q-switched and soliton mode-locked
fiber laser includes nonlinear polarization rotation (NPR), semiconductor saturable absorber
and carbon-based saturable absorber; specifically, single-walled carbon nanotubes
(SWCNT), graphene and non-conductive graphene oxide paper.
A performance comparison is made between mode-locking using NPR technique and
semiconductor saturable absorber. Based on the result, the semiconductor saturable absorber
generates better quality of mode-locked pulse than using NPR.
A single-walled carbon nanotubes (SWCNT) in a sodium dedocyl sulfate (SDS)
solution is deposited onto a fiber ferrule using dripping technique. Due to the high insertion
loss, a Q-switched pulse ensues. After adding a 200 meter single mode fiber (SMF) into the
laser cavity, the pulse energy is high enough to saturate the SWCNT saturable absorber.
Consequently, a strong soliton mode-locked pulse is generated.
A simple and compact Q-switched fiber laser is demonstrated using graphene as
saturable absorber. The saturable absorber is deposited onto a fiber ferrule by dripping a
graphene solution and then is left to dry. A Q-switched pulse performances is compared
between fiber lasers with one graphene saturable absorber and with two graphene saturable
absorbers.
A highly ordered pyrolitic graphite (HOPG) is mechanically exfoliated using a scotch
tape. The resulting graphene is transferred onto a fiber ferrule and inspected using Raman spectroscopy. The transferred graphene has been identified as a single-layer. The ensuing
pulsed fiber laser is a Q-switched, due to the large modulation depth of a single-layer
graphene. A soliton mode-locked fiber laser is then generated by adding a 200 meter SMF.
A soliton mode-locked is then demonstrated using Thulium-Bismuth doped fiber as gain
medium.
In the sixth experiment, a novel non-conductive graphene oxide paper is introduced
as a saturable absorber. The resulting soliton mode-locked fiber laser has a time-bandwidth
product (TBP) value of 0.315. The mode-locked fiber laser has a low mode-locking threshold
but the pulse gradually destroys the paper.
As a conclusion, this thesis shows the development of various techniques of
generating Q-switched and mode-locked fiber, most notably using carbon based saturable
absorber. This thesis also eases the focus on the saturable absorber, but instead, focusing on
the cavity design to generate soliton mode-locked fiber lasers. Additionally, it introduces a
non-conductive graphene oxide paper as a potential saturable absorber. |
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