| EPSRC Reference: |
GR/H52610/01 |
| Title: |
FILTERS FOR INTELLIGENT NETWORK SERVICES AND SENSORS (FINESSE) |
| Principal Investigator: |
Day, Dr SE |
| Other Investigators: |
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| Department: |
Electronic and Electrical Engineering |
| Organisation: |
UCL |
| Scheme: |
LINK |
| Starts: |
09 September 1992 |
Ends: |
08 September 1995 |
Value (£): |
133,757
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| EPSRC Research Topic Classifications: |
| Optical Communications |
Optical Devices & Subsystems |
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| Panel History: |
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Summary on Grant Application Form |
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To design and evaluate liquid crystal Fabry-Perot filters for use in wavelength division multiplexed systems and for use in spectroscopic sensors.Progress:Fabry-Perot filters filled with liquid crystal have been evaluated for application as receivers in Wavelength Division Multiplexed (WDM) systems. Finesse values of up to 100 have been measured and as expected the tuning range is greater than twice the free spectral range. The filters therefore have a tuning range of 60 to 70nm (the free spectral range) and bandwidth of less than lnm in the wavelength region for which they are designed, around 1500nm. Other filters have been designed for higher density wavelength channels and these have bandwidths of around 1A, but must be used with another wavelength selective filter, such as a grating or the former type of Fabry-Perot filter.Loss mechanisms have been identified and results compared with detailed modelling in order to quantify the losses and to reduce them. It is not possible to measure the characteristics of the individual layers on their own sufficiently accurately to predict the performance and so comparison with modelling of the cavity as a whole is important to quantify the losses by origin. Gaussian beam propagation through the liquid crystal in a resonant cavity has also been modelled, since the input will be from optical fibre. This has been used in the design of double pass configurations and will be used to predict the performance of the filter in the cavity of a laser for use as a tunable transmitter.Polarisation insensitive operation is essential for the use of such filters in telecommunication networks. Twisted nematic configurations have been measured to find the range of the polarisation insensitive operation. A new method of achieving polarisation insensitive operation has been suggested and this has been modelled thoroughly and shown to be a satisfactory solution in many circumstances.
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Key Findings |
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Potential use in non-academic contexts |
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Impacts |
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| Description |
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| Summary |
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| Date Materialised |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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