This thesis describes work on fibre transitions made in photonic crystal fibres (PCF)
and conventional standard fibres. Three post-processing techniques were used to make
the transitions: fibre tapering, ferrule drawing and a new technique – PCF hole inflation.
All these methods change the fibre dimensions on a centimeter scale while maintaining
very low loss.
In the hole inflation technique, cladding holes are pressurized and can be enlarged
while heat-treating, unlike other techniques where the holes can only be reduced in size.
Controlled hole expansion was used to produce devices for applications such as
supercontinuum generation. Furthermore, differential pressurization of holes could
create a diversity of core shapes in a PCF section. For example they were investigated
to improve interfacing of laser diodes to fibres.
Differential pressurization was also used to introduce new cores into PCFs.
Introducing a larger core asymmetrically by the original core resulted in a fundamental
to second-order mode conversion with a high extinction ratio. Alternatively, similar
mode conversion was demonstrated by fusing two unequal standard fibres. Also with
standard fibres, low-loss multimode to single-mode fibre transitions were made using a
modified fibre fabrication technique.
These fibre transitions and optical devices have a wide range of potential
applications, for example in supercontinuum generation and low-loss interfacing of
fibres to other optical systems.
|Date of Award||1 Jan 2009|
|Supervisor||Tim Birks (Supervisor)|
- Optical fibres
- optical couplers