Comparison of the Thermal Tuning Capability of Different Types of Bragg Grating Filters for Wavelength Division Multiplexing Applications M. J. N. Lima, A. L. J. Teixeira, J. R. Ferreira da Rocha Department of Electronics and Telecommunications and Institute of Telecommunications, University of Aveiro, 3810-193 Aveiro, Portugal Tel: +351 234 370383, Fax: +351 234 381128, E-mail: mmcc@ua.pt O. Frazão INESC Porto – UOSE, Rua Campo Alegre, 687, 4169-007 Porto, Portugal P. S. B. André Department of Physics and Institute of Telecommunications, University of Aveiro, 3810-193 Aveiro, Portugal