Variable Optical Attenuator Driven By Fluid Pressure

Variable optical attenuator is an optical device that can dynamically adjust the optical power and balance the channel gain,which is widely used in fiber optic communication,sensing and signal processing,etc.It is an indispensable basic device in wavelength division multiplexing system.With the rapid development of optical communication,the demand for optical communication devices is growing,and the variable optical attenuator has a broad application prospect.Currently,there are various classifications and implementation principles of variable optical attenuators,but there are still problems such as complex structure,difficult integration,high production cost and insufficient optical performance.Compared with other types of variable optical attenuators,fiber dislocation type variable optical attenuators have the advantages of wide attenuation range,high reliability,low insertion loss,high accuracy,non-polarity adjustment and realization of multiple attenuation,etc.,which are widely used in fiber optic communication,optical testing and fiber optic sensing fields.There are various implementation principles of fiber dislocation type variable optical attenuators,including electromagnetic drive,thermal drive,etc.,but there is no report on the fluid pressure driven fiber dislocation type variable optical attenuator.The purpose of this paper is to design a new type of fluid pressure-driven variable optical attenuator by combining the fluid pressure-driven method and the optical fiber dislocation-type variable optical attenuator.The device not only has the advantages of large dynamic range,low insertion loss and high accuracy of fiber dislocation type variable optical attenuator,but also can change the accuracy of variable optical attenuator by configuring different thickness of thin film,avoiding the defect of general variable optical attenuator accuracy is not configurable,and realizing the organic combination of high performance variable optical attenuator and accuracy configurable.The main research content of this paper: based on a lot of research and theoretical study,a variable optical attenuator based on fluid pressure drive is proposed.The working principle is to drive the fiber movable carrier platform by fluid pressure,which drives the input fiber and fixed output fiber to undergo lateral displacement to realize the precise control of optical energy attenuation.In this paper,the research is carried out from both simulation and experiment,combining the principles of hydrodynamics and solid mechanics,using COMSOL Multiphysics software to simulate the multiphysics field dynamics of the driving part of the device;using the finite-domain difference method,the optical fiber coupling efficiency is analyzed by Lumerical FDTD software for optical simulation.Following that,the device material,dimensions and other parameters were determined and experimental samples were prepared.The experimental results show that the dynamic tunable range of the attenuator is greater than 60 d B,the insertion loss is 1.24 d B,and the wavelength dependent loss is less than 1 d B.When the dynamic range of optical attenuation is set to 10 d B and 40 d B,the tuning accuracy is better than 0.04 d B and 0.11 d B for the configuration of 0.5 mm film thickness,respectively.The accuracy of the variable optical attenuator can be adjusted by configuring different film thicknesses of the variable optical attenuator.