tailieunhanh - Báo cáo " Analysis and design of multimode interference coupler based racetrack resonators with the effects of higher order modes "

The design and analysis of a racetrack resonator based on a multimode interference (MMI) coupler are presented in this paper. In order to describe the characteristics of an MMI coupler, a matrix description of the MMI coupler, which takes into account the effect of higher order modes in the structure, is developed. A design approach that is based on this matrix description is proposed. The usefulness of this design method is illustrated by means of an example based on Silicon on Insulator (SOI) technology | VNU Journal of Science Natural Sciences and Technology 23 2007 263-268 Analysis and design of multimode interference coupler based racetrack resonators with the effects of higher order modes Le Trung Thanh University of Transportations and Communications Lang Thuong Dong Da Hanoi Vietnam Received 27 July 2007 Abstract. The design and analysis of a racetrack resonator based on a multimode interference MMI coupler are presented in this paper. In order to describe the characteristics of an MMI coupler a matrix description of the MMI coupler which takes into account the effect of higher order modes in the structure is developed. A design approach that is based on this matrix description is proposed. The usefulness of this design method is illustrated by means of an example based on Silicon on Insulator SOI technology. 1. Introduction Racetrack resonators are promising devices for applications in the field of optical communication. Using this structure basic signal processing functions such as wavelength filtering routing switching modulation and multiplexing can be achieved 1 2 . Most racetrack resonators have been designed and fabricated using directional couplers or MMI couplers as a coupling element between the ring and the bus waveguides. The coupling element is usually modelled by using a 2x2 universal transmission matrix. However due to the presence of bent waveguides in the racetrack section additional higher order modes can be excited at the input of the coupling region 3 4 . Tel. 84-4-7910197. E-mail thanhvn_au@ They can be coupled then to output fields and have an effect on the transmission characteristics. As a result this simple model can be applied only in ideal cases in which the device is lossless and the matrix is unitary. In 3 the design ideas of MMI coupler based racetrack resonators for practical fabrication and designs have been proposed for the first time. It is different from the approach given in 4 for a double-ring resonator in this .