Designing waveguide filters with optical thin-film computational tools

Abstract

By comparing computation results obtained with the film mode matching (FMM) method to those obtained with the Abelès optical thin-film computation method, we demonstrate that the Abelès method may be used to compute the spectral transmittance or reflectance of filters for waveguides. Some classical examples of integrated optics components are presented to check the validity of the Abelès computation method (ACM) for waveguides: an integrated Bragg reflector, an integrated narrow band-pass filter and a high-pass dichroic filter. Results obtained with the Abelès method can be very close to those obtained with the rigorous FMM method. Moreover, computation time can be divided by a factor of 10,000 on a conventional PC. An automatic synthesis software based on the ACM is then used to design an integrated gain flattening filter. Thus, we show that spectral filters for waveguides of arbitrary spectral transmittance or reflectance can be designed with thin-film synthesis softwares based on the well-known Abelès method.