MEMS for free-space optical switching

Micro-electro-mechanical-systems (MEMS), with its unique ability to integrate electrical, mechanical, and optical elements on a single chip, has demonstrated high potential for realizing optical components and systems in compact and low-cost form. Recently, this technology has been applied to wavelength-division-multiplexed (WDM) networks, and resulted in advances in several network elements, including switches, filters, and modulators. For future WDM networks with enormous transmission capacity, optical switching for optical-layer crossconnects is of particular interest due to its transparency to steady advances in the per-channel bit-rate. In this paper, we review various micromachined optical-switching technologies, focusing on the free-space MEMS optical switch we have demonstrated and recent progress. We also show the unique features of this technology in implementing important network functions in integrated form, such as bridging in network restoration and maintenance, integrated signal-monitoring, connection-path verification, and network connection-symmetry.