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Refraction and Optical Fibres

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Title: Refraction and Optical Fibres


1
Refraction and Optical Fibres
Dr Murray Thompson University Senior
College Murray.thompson_at_adelaide.edu.au
Prof Tanya Monro Centre of Expertise in
Photonicstanya.monro_at_adelaide.edu.au
2
Refraction and Optical Fibres
  • This material has been developed as a part of
    the Australian School Innovation in Science,
    Technology and Mathematics Project funded by the
    Australian Government Department of Education,
    Science and Training as a part of the Boosting
    Innovation in Science, Technology and Mathematics
    Teaching (BISTMT) Programme.

3
Refraction and Optical Fibres
  • When light travels from one medium to another it
    changes speed.
  • It also changes direction.

4
Refraction
  • From a fast medium to a slow medium, the light
    bends towards the normal.

5
Refraction
  • From a slow medium to a fast medium, the light
    bends away from the normal.

6
Snells Law of Refraction
which is the refractive index from medium 1 to
medium 2.
7
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8
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9
Total Internal Reflection
  • When the light goes from slow to fast, as the
    angle of incidence is increased, the angle of
    refraction increases as well, until it reaches
    90?.
  • The angle of incidence when this happens is
    called the critical angle.

10
Total Internal Reflection Critical Angle
  • Fast medium eg air

11
Total Internal Reflection
  • Beyond the critical angle, no refraction is
    possible and the light is said to totally
    internally reflect.

12
Total Internal Reflection
  • No refraction is possible beyond the critical
    angle.

13
Below the critical angle
14
At the critical angle
Note the reflected ray
Note the refracted ray at grazing angle
colour dispersion
15
Beyond the critical angle Total internal
reflection.
16
Total Internal Reflection
Snells law
17
Guiding Light
  • Need to guide light to communicate optically
    between points
  • First observation of light guiding made by John
    Tyndall
  • Based on total internal reflection

18
Photonics is Everywhere
Photonics is the science of the photon, the
fundamental particle of light.
Compact tunable lasers for optical
telecommunications
Optical fibres for structural strain sensing
Sea mice use photonic crystal effects to warn off
predators
19
Optical Fibres Beyond Telecommunications
  • Optical fibres can also have applications in
  • Medicine
  • Biological and genetics research
  • Defence
  • Industrial materials processing
  • Chemical and pollution sensing
  • Next generation lasers
  • Optical data processing
  • Transmitting light beyond the near-IR
  • And so new types of optical fibres are needed

20
Microstructured Optical Fibres
fibres with micron-scale transverse features
21
Why Microstructure?
  • Engineering materials on the scale of the
    wavelength of light can lead to materials with
    new optical properties
  • Using air as the cladding of an optical fibre
    means that fibres can be made from a single
    material
  • Light can be used to probe the properties of
    materials located within the air holes
  • Here at Adelaide University, we are setting up
    facilities to develop a whole new class of
    optical fibres soft glass microstructured
    optical fibres

22
Overview of Fibre Activities at Adelaide
University
23
Extrusion
glass billet
OD29mm h34mm
Stainless steel die
Structured glass preform
24
Extrusion Preform Variety
  • Structured preforms in one step
  • Flexible geometry
  • Geometric reproducibility
  • Successfully applied to lead silicates,
    tellurites, chalcogenides, bismuthates, lead
    germanates

25
Careers in Photonics
Centre of Expertise in PhotonicsSchool of
Chemistry PhysicsUniversity of
Adelaide Professor Tanya Monro Director
www.chemphys.adelaide.edu.au/physics/research/phot
onics
26
Science Degrees at Adelaide University
  • Bachelor of Science (BSc)
  • - Biomedical sciences
  • - Biophysics
  • - Chemistry
  • - Environmental biology and Ecology
  • - Geosciences (Geology and Geophysics)
  • - Molecular biology and Biotechnology
  • - Physics
  • - Psychology and Behavioural Sciences

27
A Science Degree Provides
  • Scientific knowledge
  • Technical skills
  • Problem solving skills
  • Analytical skills
  • Critical thinking
  • Communication skills
  • Initiative
  • Teamwork
  • Time management
  • Responsibility
  • Confidence

And Leads to a Career in
  • Government
  • Health
  • Education
  • Private industry
  • Consultants
  • Research laboratories
  • Own business

28
Pre-requisites
  • BSc
  • Two science subjects, one chosen from
  • Chemistry, Maths Studies, Specialist Maths,
    Physics
  • one from
  • Biology, Chemistry, Geology, Physics
  • Specialist Programs with Physics
  • Physics,
  • Maths Studies and
  • Specialist Maths

29
BSc (Optics and Photonics)
  • Optics and Photonics is a steadily growing sector
    in industry
  • Australian tertiary institutions are not
    producing enough trained people
  • (even allowing for the bust in the boom/bust
    cycle ! )
  • Physics graduates are readily employable in this
    industry
  • Named degree makes qualification more
    recognisable
  • Adelaide is rapidly developing strength in
    defence photonics (potential employers include
    DSTO, Tenix, BAE systems
  • Wide range of other opportunities including in
    medicine (eg ophthalmology), communications, etc
  • Attractive career opportunities with scope for
    creativity and practical relevance

30
Job opportunities in photonics
  • There are opportunities for people with photonics
    training in Academia, Industry, Defence
  • Requires study of physics and mathematics
  • Bachelor of Science (Optics and Photonics)
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