Photonic Devices - Bragg gratings

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This graph shows typical experimental & theoretical Grating reflection spectra. The peak wavelength is sensitive to changes in temperature (0.01nm/ degree C) as well as changes in strain (0.001 nm if the fibre stretches by 1 part in 106), making Bragg gratings useful in fibre sensors.

Theory

Experiment

Peak shifts with temperature and / or strain

Reflectivity (%)

Victoria University

Optical TechnologyResearch Laboratory

Special fibres for special applications

Current sensing on HV powerlines

“Non-zero dispersion-shifted fibre” for long haul high bit rate links

Optical fibre wound around conductor can safely sense magnetic fields

Erbium-doped fibre amplifier for all-optical repeaters in long haul communication links

Planar optical waveguides

Planar waveguides written into a polymer on a silicon wafer using a focused laser

Microscope photo of a planar waveguide device

Planar Optical Waveguides

Planar waveguides can also be built up layer by layer, as has been done for silicon chipsSequence of processing steps:

• Cladding deposition

• Core deposition

• Masking

• Etching

• Cladding deposition

This allows quite complex waveguide structures to be fabricated over a large area in a short time

Microscope photo of a buried channel waveguide showing the ~ 6 micron core (bright) against a darker cladding

Microphotonics - a new frontier

Micro-electro-mechanical systems (MEMS)In recent years, new kinds of moving objects such as tiny motors, pumps and moving mirrors have been fabricated on micrometer scales. This tiny electronically tiltable mirror is a building block in devices such as all-optical cross-connects and new types of computer data projectors.

MEMS array configured as an optical crossconnect