New method of optical variable attenuator with polymer-network liquid crystals

Abstract

Abstract The optical variable attenuators (VOA) play important roles in wavelength division multiplexing (WDM) transmutation systems, this paper describes a new type variable optical attenuator made by using fiber U-grooves in silicon wafer and polymer-network liquid crystal. Fibers are placed in the U-grooves of silicon wafer, and the polymer-network liquid crystal is filled in the gaps between the ends of the docking fibers. The paper explains the principle of the attenuator operation and pres ents experimental method in laboratory. Keywords : wavelength division multiplexing, polymer-network liquid crystal, variable optical attenuators, silicon wafer, fiber U-grooves 1. Introduction The variable optical attenuator (VOA) is an essential optical component aimed to continuously adjust the optical power transmitting in optical wave-guide. It can keep the optical signal to carry through the expectant and quantitative attenuation according to the request of user in the fiber transmission line. The VOA has very broad application in the fiber-optic communications, fiber sensor, and fiber measurement systems. Nowadays the marketable potential of the VOA is greatly, its output is just inferior to the linker and coupler during the optical passive components. In recent years, to respond to the rapid growth in demand for the wide band optical communications networks, the optical attenuator has played very important roles in wavelength division multiplexed (WDM) systems. In which multiple wavelengths are multiplexed on a single optical fiber, this makes it necessary to use an optical component known as a variable optical attenuator (VOA) to flatten the gain profile by applying to the Erbium-doped fiber amplifiers (EDFA) and to be a channel power equalizer with a dynamically signal-adjusting function that is substantially independent of wavelength, Fig.1 shows a basic diagram of a DWDM system with a VOA and the function it provides