Abstract
(Englisch)
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The aim of this project is to thoroughly study, develop and assess photosensitive planar technology in a system context, through key devices for future optical metropolitan networks. Selected devices are multi-channel Optical Add and Drop Multiplexers (OADM) where any wavelength (or waveband) is added/dropped among several wavelengths (or wavebands). Re-configurable operation is ensured through the use of thermo-optic switches. Where today three components are required for de-multiplexing, routing and multiplexing, here a single component is needed. Beyond a major advance in terms of switched granularity, this device offers the excellent spectral efficiency of Bragg gratings. All aspects are covered: planar waveguide process, UV writing (grating, waveguide), characterisation of underlying mechanisms, thermo-optic switches, devices design and realisation including packaging, as well as system tests and assessment.
Objectives:
The overall objective is to thoroughly study, develop and assess in a system context photosensitive planar technology, through key pilot devices, ensuring an optimal development.
Objectives are three fold:
(i) to establish an optimised process suitable for devices realisation;
(ii) to produce and optimise, under systems specifications, key pilot components which are representative of the potential of this technology, and are advantageously realised through it;
(iii) to provide system assessment of the devices performances, and more generally assess the potential and impact of this technology on photonics networks.
Work description:
The technical approach is based on the close relationship between four main tasks:
1/ System specification and evaluation: to define devices specifications, to characterise devices in system tests representative of their functionality, ensuring feedback and optimisation.
2/ Process study: to develop technologies required to produced the identified devices: - Wafer process: Flame Hydrolysis Deposition will be thoroughly studied, whilst a new process will also be characterised. Work concerns: mastering of refractive index, photosensitivity and opto-thermal characteristics of layers, uniformity across wafer, low loss waveguide, nulling of birefringence, deep etching for low polarisation dependence thermo-optic switches. - UV processing for:(i) realising several grating types required for devices;(ii) UV patterning of waveguide and more complex structures;(iii) photosensitivity enhancing, thermal annealing conditions and lifetime predictions.- Study and characterisation of the underlying mechanisms and optical properties in order to feedback on global process optimisation.
3/ Devices implementation: to study, design, realise and package devices. Identified devices are multi-channel Optical Add and Drop Multiplexers (OADM) switching wavelengths or wavebands in re-configurable operation. Envisaged solutions are based on Mach-Zehnder interferometer, directional and multimode interference (recently reported) coupler. Work will focus on the implementation of elementary OADM structures with low chromatic dispersion Bragg gratings and of their cascadability with a minimum bending radius for maximum denseness, together with the implementation of low polarisation dependent thermo-optic switches.
4/ Assessment of progress and results.
Milestones:
- Optimised process: .wafer, etched waveguides, thermo-optic switches low polarisation dependent. UV written grating with low chromatic dispersion. UV written waveguides for fully written OADMs. process for photosensitivity enhancement and stabilisation -Delivery of devices- System characterisation of devices, analysis of system impact.
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