Refraction and Optical Fibres

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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
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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.

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Refraction and Optical Fibres

• When light travels from one medium to another it
  changes speed.
• It also changes direction.

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Refraction

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

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Refraction

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

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Snells Law of Refraction
which is the refractive index from medium 1 to
medium 2.
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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.

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Total Internal Reflection Critical Angle

• Fast medium eg air

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Total Internal Reflection

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

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Total Internal Reflection

• No refraction is possible beyond the critical
  angle.

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Below the critical angle
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At the critical angle
Note the reflected ray
Note the refracted ray at grazing angle
colour dispersion
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Beyond the critical angle Total internal
reflection.
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Total Internal Reflection
Snells law
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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

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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
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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

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Microstructured Optical Fibres
fibres with micron-scale transverse features
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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

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Overview of Fibre Activities at Adelaide
University
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Extrusion
glass billet
OD29mm h34mm
Stainless steel die
Structured glass preform
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Extrusion Preform Variety

• Structured preforms in one step
• Flexible geometry
• Geometric reproducibility
• Successfully applied to lead silicates,
  tellurites, chalcogenides, bismuthates, lead
  germanates

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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
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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

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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

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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

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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

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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)