A Contamination Sensor Based on an Array of Microfibers with Nanoscale-Structured Film

Guorui Zhou,Hai-Bing Lü,Hongbin Wang,Haijun Wang,Xiaodong Yuan,Hai Zhou,Xinxiang Miao

doi:10.1155/2014/301095

Abstract

A contamination sensor based on an array of microfibers with nanoscale-structured film using evanescent field is proposed and demonstrated theoretically and experimentally. When the molecular contaminants deposit on the nanoscale-structured film, the refractive index of the film will change and the additional loss will be produced due to the disturbance of evanescent field. The possibility of the sensor is demonstrated theoretically by using three-dimensional finite-difference time domain (3D-FDTD). The corresponding experiments have also been carried out in order to demonstrate the theoretical results. Microfibers are fabricated by using hydrogen-oxygen flame-heated scanning fiber drawing method and the nanoscale-structured film coated on the surface of microfibers is deposited by using dip coating process. Then an array of microfibers is assembled to demonstrate the feasibility of the device. The experimental results show that contaminants detection with the device can agree well with the results measured by the laser-scattering particle counter, which demonstrates the feasibility of the new type of contaminant sensor. The device can be used to monitor contaminants on-line in the high-power laser system.

Highlights

For high-tech industries, such as optical components or semiconductor, particle contaminants associated with environment control and cleanroom and molecular contaminants must be well controlled
The additional loss caused by contaminants adhered to film is simulated by means of the three-dimensional finitedifference time-domain (3D-FDTD) method
The flame-heated scanning drawing method has certain advantages compared with laser drawing method; both theoretical and experimental results show that the laser power required for drawing microfibers with a uniform diameter is impractically large [18]

Summary

Introduction

For high-tech industries, such as optical components or semiconductor, particle contaminants associated with environment control and cleanroom and molecular contaminants must be well controlled. A few methods of contaminant monitor on-line had been applied successively [4, 5], such as laser-scattering particle counters, microelectromechanical resonators and quartz crystal microbalance. They are not applicable any more in the harsh environment because of vacuum condition or strong scattered laser energy. Compared with other contaminants sensors [16, 17], the new type of sensor is bases on the evanescent field of microfibers surface, so the device is promising for its low cost and easy fabrication. The device exhibits significant advantages, such as high sensitivity, compact and simple structure, and immunity to electromagnetic fields

Theoretical Analysis

Experimental Results

Discussion and Conclusion