Transition and comparison between directional couplers and multimode interferometer based on ridge waveguides

Stevanus Darmawan; Shuh Ying Lee; Chee-Wei Lee; Mee-Koy Chin

doi:10.1117/12.575986

17 January 2005 Transition and comparison between directional couplers and multimode interferometer based on ridge waveguides

Stevanus Darmawan, Shuh Ying Lee, Chee-Wei Lee, Mee-Koy Chin

Author Affiliations +

Proceedings Volume 5644, Optoelectronic Devices and Integration; (2005) https://doi.org/10.1117/12.575986
Event: Photonics Asia, 2004, Beijing, China

Abstract

In this paper, we present a comparison analysis between directional couplers (DC) and multi-mode interferometers (MMI) based on high-index contrast ridge waveguides. It is found that the two devices are intimately related as the MMI is structurally derived from the DC. For the first time, the continuous evolution from the two-mode coupling characteristic of DC to the two-mode interference and multi-mode interference of MMI is demonstrated. The resulting MMIs are compared with the DC in terms of coupling length, polarization dependence, excess loss, and fabrication tolerances. We show that practical directional couplers with reasonable gap size can also be quite compact and have the same coupling length for both TE and TM polarizations. Consequently, the DC can be just as polarization insensitive as the MMI. These features, however, require careful design control involving a large set of design parameters. By comparison, the MMI design is more robust and involves fewer design variables.

Citation Download Citation

Stevanus Darmawan, Shuh Ying Lee, Chee-Wei Lee, and Mee-Koy Chin "Transition and comparison between directional couplers and multimode interferometer based on ridge waveguides", Proc. SPIE 5644, Optoelectronic Devices and Integration, (17 January 2005); https://doi.org/10.1117/12.575986

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