Design of an ultrashort Si-nanowaveguide-based multimode interference coupler of arbitrary shape
2008 (English)In: Applied Optics, ISSN 0003-6935, E-ISSN 1539-4522, Vol. 47, no 1, 38-44 p.Article in journal (Refereed) Published
A design procedure for an arbitrarily tapered multimode interference (MMI) coupler based on Si nanowaveguides is presented. First a series of the effective indices of the zeroth and first eigenmodes in multimode waveguides are obtained as the core width increases by using a full-vectorial finite-difference method. Two polynomial functions are used to fit the two relations between the effective indices and the core width. The phase difference Delta phi between the zeroth and first eigenmodes can then be easily calculated when the light goes through any given arbitrarily tapered MMI section. By making the phase difference Delta phi equal to a certain value Delta phi(0) required for an N-fold self-imaging, the length of a MMI coupler is determined. With the present design procedure, an ultrashort 2 x 2 parabolic MMI coupler is designed as an example. The size of the designed ultrashort MMI section is only similar to 1.4 mu m X 4.7 mu m.
Place, publisher, year, edition, pages
2008. Vol. 47, no 1, 38-44 p.
nanowire wave-guides, mmi couplers, devices, fabrication, technology, bends
IdentifiersURN: urn:nbn:se:kth:diva-17282ISI: 000252757600006ScopusID: 2-s2.0-40749147682OAI: oai:DiVA.org:kth-17282DiVA: diva2:335325
QC 201005252010-08-052010-08-052013-11-19Bibliographically approved