In brief - Tapping the light fantastic

The potential for cost-effective optical power monitoring created on a silicon platform using widely available techniques has been demonstrated by a group of researchers from Canada, the US and the UK.

An integrated optical tap monitor was fabricated by the conversion of a commercially available variable optical attenuator through defect engineering in a way that also suggests monitoring could be integrated with chips possessing greater functionality.

Modifying functionality of variable optical attenuator to signal monitoring through defect engineering
Electron. Lett. -- 4 February 2010 -- Volume 46, Issue 3, p.234–236

J.K. Doylend (1), A.P. Knights (1), B.J. Luff (2), R. Shafiiha (2), M. Asghari (2) and R.M. Gwilliam (3)
(1) McMaster University, Department of Engineering Physics, Hamilton, Canada
(2) Kotura Inc., Monterey Park, USA
(3) University of Surrey, Advanced Technology Institute, Guildford, United Kingdom

A commercial silicon-based variable optical attenuator has been converted to a low bandwidth (quasi-CW) light monitor through an ion implantation and annealing process. The measured total optical loss of the device is <5 dB while the responsivity per tapped fraction is 1 mA/W/dB. The straightforward manner in which the monitoring functionality is induced suggests a cost-effective route to CW optical monitors using a widely available commercial product.

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