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Proceedings Paper

Use of asymmetric dual-cavity filters to track small H and L variations as a tool to increase yield of DWDM filters
Author(s): David I. C. Pearson; Paul Luff; Mervyn Davis; Arthur T. Howe
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Paper Abstract

We show that asymmetric dual cavity filters, comprising one cavity of Ta2O5 (H) and the other of SiO2 (L), can be designed so that the asymmetry in the transmission intensity between the two peaks is sensitive enough to detect H/L ratio changes down to 1.0001. This accuracy is necessary for precise uniformity determinations for 100 GHz filter production. We show that interpretation of asymmetry changes is still valid despite small absorption or scatter losses due to either of the materials, and also despite small layer thickness errors which have been optically compensated by the optical monitoring system during deposition of the filter. We illustrate the use of asymmetry in adjusting the H/L ratio within 1.0001 at larger and smaller radii away from the optical monitor band on an 8" diameter disc, and also for checking azimuthal variations. Combining the asymmetry data with the wavelength shift data enabled the individual H and L calibrations to be deconvoluted from the multilayer data. This technique is far more accurate than measuring individual material calibration runs, and also takes account of multilayer effects such as interfacial mixing and process sequencing. Ion beam sputtering process parameters were varied to maximize the uniformity and increase the yield for cost-reduction of 100 GHz filters, and the application to 50 GHz filter yield enhancement is discussed.

Paper Details

Date Published: 9 July 2003
PDF: 8 pages
Proc. SPIE 4998, Photonic Integrated Systems, (9 July 2003); doi: 10.1117/12.475756
Show Author Affiliations
David I. C. Pearson, Nordiko Ltd. (United Kingdom)
Paul Luff, Nordiko Ltd. (United Kingdom)
Mervyn Davis, Nordiko Ltd. (United Kingdom)
Arthur T. Howe, Chromatel (United States)

Published in SPIE Proceedings Vol. 4998:
Photonic Integrated Systems
Andrew R. Pirich; Ray T. Chen; Louay A. Eldada; Louay A. Eldada; Andrew R. Pirich; Joseph C. Chon; Paul L. Repak; Paul L. Repak; Ray T. Chen; Joseph C. Chon, Editor(s)

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