Using 2 x 2 switching modules to build large 2-D MEMS optical switches

Abstract

MEMS optical switch technology is one of the key technologies in Wavelength Division Multiplexing (WDM) optical networks. Although the 2-D MEMS optical switch technology is mature, the commonly used crossbar architecture is not amenable to building large switches. In this paper, we propose a design of 2 × 2 switching modules, and use it to build large 2-D MEMS optical switches with architectures such as Spanke-Beneš and Beneš networks.

Alternative structures for two-dimensional MEMS optical switches [Invited]

“…Using a mix of the approaches may increase the number of inputoutput ports in some cases, but the problem persists. One way to solve the problem is to segment the paths inside the switches and collimate the optical signals segment by segment [18]. From Subsection 2.E, an optical signal with wavelength λ has a minimum beam radius (2λD/π) 1/2 at the midpoint of a free-space propagation path of length 2D if it has been collimated and focused onto the path midpoint.…”

“…Complicated routings for the optical signals inside the switches are also required [16]. Another approach is to divide the input-to-output paths into multiple individually recollimated segments [17,18]. Extra collimating optical devices are needed, e.g., collimating lenses [17], or concave mirrors [18].…”

“…Another approach is to divide the input-to-output paths into multiple individually recollimated segments [17,18]. Extra collimating optical devices are needed, e.g., collimating lenses [17], or concave mirrors [18]. In principle, the mirror size can be independent of the input-to-output path length [18], but the number of ports N would still be limited by other factors such as the required number of mirrors, complexity of the optical signal routings, and the number of reflections to the optical signals.…”

“…Extra collimating optical devices are needed, e.g., collimating lenses [17], or concave mirrors [18]. In principle, the mirror size can be independent of the input-to-output path length [18], but the number of ports N would still be limited by other factors such as the required number of mirrors, complexity of the optical signal routings, and the number of reflections to the optical signals. Owing to the demands of large reliable OXCs, in this paper we investigate the pros and cons of building large 2-D MEMS optical switches with these approaches.…”

Optical-switch Benes architecture based on 2-D MEMS

“…Compared to other alternative architectures (Crossbar, LSwitching matrix [9], [10], Array Interconnection [11]) the Benes network allows to achieve good loss uniformity (differential loss) and low number of reflections with a small number of active Switching Elements (SEs), asymptotically increasing as O[N log 2 (N )] (to be compared to the O[N 2 ] of the Crossbar). The implementation does not require to tilt mirrors at a large number of different angles, as in a recently proposed 2-D MEMS implementations of the Benes architecture [12]. On the contrary, in order to simplify the fabrication process and reduce the tolerance constraints on mirror alignment, the proposed design approach is such that all the mirrors are oriented along only two orthogonal directions and are located on a regular grid on the substrate.…”