Study On Fabrication Technology Of Novel Liquid Crystal Variable Optical Attenuator

With the development of science and technology, the fiber optic communication has already become an important branch of the communication field. Following the rapid development of the fiber optic communication system, Passive device technology, as the foundation of optical communication, develops rapidly too. Optical attenuator is a kind of device aiming at reducing the light power transmitting in wave guide and can decay the power of the light signal as much as the user expects. It is a kind of very important passive device of fiber optics and has become the most basic optical passive device with connector, coupler, isolator etc. together. With the rapid development of all optic-networks, the optical attenuator is playing an important role in wavelength division multiplexing (WDM) systems, and the market demand increases very swiftly and violently.At present, the components in optical network are in more demand of dealing optical signal with high reliability, power consumption little and miniaturization with the optic communication development. Utilizing the polymer network liquid crystal material, combining body silicon micro machining technology and liquid crystal technology together we are developing a novel polymer dispersed liquid crystal variable optical attenuator. The working mechanism of polymer dispersed liquid crystal variable optical attenuator is shown as below: Liquid crystal molecules are inserted in the middle of two transparent conductive electrodes. If no voltage is applied on the electrodes, molecules arrange the liquid crystal unordered, so the incidence light beam has been affected by scattering and the output optic power is very small. When the voltage is applied on the electrodes, molecules arrange the liquid crystal in order and present the transmission state, so the output optical power can be very heavy. In this process, optical power of transmission alters from minimum to maximum.The key problem to solve is to design and carry on the fabrication technology of the prototype device of the attenuator in the project. It is reported abroad using planar wave guide or optic fiber glass capillary structure at present. We adopt the silicon micro machining technology to get self-aligned grooves on (100) silicon wafer, design liquid crystal little box structure and combine the polymer network liquid crystal technology together to find out the fabrication technology of the prototype device of the attenuator. This research scheme at present not still seen at home and abroad is innovative. The research scheme adopting silicon micro machining technology connects optic fiber coupling structure and decay function part into a whole, making the device architecture easier to integrate. Comparing with other MEMS micro-structure optical attenuators, our designing fabrication process is comparatively simple; comparing with machinery attenuator made by traditional technology, our attenuator has the advantages such as a small and exquisite volume, low costs, being apt to realize many arrays of the devices. There are very great market potential and wide application prospect.A novel variable optical attenuator(VOA)based on polymer-dispersed liquid crystals(PDLC) is presented. The device employs PDLC into the optical path of two collimated single-mode fibers with the transparent ITO electric thin films as the electrode of the PDLC. Utilized the electro-optic properties of PDLC under the condition of the different electric field intensity to realize the continuous controllable attenuate on the power of the optical path.The VOA was fabricated by silicon micromachining techniques and the performance is evaluated. The measuring results show the insertion loss of the fabricated VOA is below 0.85dB,maximum attenuation range is about 14 dB at 1550nm ,and a applied voltage of VOA less than 57 volt. Finally,we Manufactured the the molding tool of fiber-optic slot making use of the high fidelity characteristic in the Process of polymerization of the PDMS materials . The whole technical process will cost 10 hs. The molding tool have the advantages the high hardness and long working life . After a series of unsuccessful technology attempts,we can make the high quality molding tools . The process need lower facility request,shorter time,and have higher quality thoroughfare. being acclimated to the fast executing research time,and the demands of making the small batch size,high quality chips.