Ultra-High-Capacity Optical Communications and Networking: Surface-Tension-Driven Liquid Space Optical Switching (SLISOS) Systems

Northwestern University, Evanston IL

Investigators

Abstract

This proposal was submitted in response to the solicitation NSF 01-65 on "Ultra-High Capacity Optical Communications and Networking." This proposal deals with an innovative liquid space optical switching (LISOS) method based on surface-tension-driven microfluidics. The final goal of this research targets ultra high capacity, e.g., 1024x1024, optical cross connect switching systems. Some of the featured aspects of performance include fast switching time (~ 100s), low insertion loss (~ 0.2 dB), low crosstalk (~ 40dB), low power consumption (~ 10W per switch), inherent latching function (i.e., no continuous power), and reversible switching action. This technology will enable next generation ultra high-speed optical communication at a very low cost. As the signal traffic for optical fiber communication rapidly increases, all-optical switching technology without opto-electronic conversion is considered the ultimate goal. The conventional switching scheme using optical-electrical-optical signal conversion simply cannot follow the high signal rate (e.g., GHz - THz range) requirement for next generation network communication. The use of micromachined mirrors for the direct switching of light signals, which eliminates the signal conversion process, has been a major alternative to the conventional approach. However, the extension of the micromirror approach to ultra high capacity optical cross connect is facing the fundamental limits in loss characteristics and manufacturing costs (labor and time). The use of thermal-bubble-actuated index matching liquid has been recently proposed as an alternative to the micromirror-based approach. The actuation characteristic, however, is not desirable due to large, continuous power requirement. Furthermore, the thermal stability requirement of the liquid restricts the choices of optically optimum working liquids. In this research, surface tension - a dominant force in microscale fluid motion - is proposed as an actuation mechanism for LISOS. The novel electrical and mechanical control of surface tension (Electrowetting and Mechanical Wetting) are used as microactuation mechanisms with extremely low power consumption, reliable operation, and high speed actuation. The proposed team, combining microfluidics technology with the photonics capability, will design, fabricate, and test a surface-tension-driven LISOS system (SLISOS) suitable to the high volume, high speed requirement of the emerging optical communication requirements with the aforementioned performance.