A Transflective Nano-Wire Grid Polarizer Based Fiber-Optic Sensor

Jing Feng,Xiao-Wen Lin,Yun Zhao,Yan-Qing Lu,Wei Hu,Fei Xu

doi:10.3390/s110302488

Jing Feng, Xiao-Wen Lin + Show 4 more

Open Access

https://doi.org/10.3390/s110302488

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Abstract

A transflective nano-wire grid polarizer is fabricated on a single mode fiber tip by focused ion beam machining. In contrast to conventional absorptive in-line polarizers, the wire grids reflect TE-mode, while transmitting TM-mode light so that no light power is discarded. A reflection contrast of 13.7 dB and a transmission contrast of 4.9 dB are achieved in the 1,550 nm telecom band using a 200-nm wire grid fiber polarizer. With the help of an optic circulator, the polarization states of both the transmissive and reflective lights in the fiber may be monitored simultaneously. A kind of robust fiber optic sensor is thus proposed that could withstand light power variations. To verify the idea, a fiber pressure sensor with the sensitivity of 0.24 rad/N is demonstrated. The corresponding stress-optic coefficient of the fiber is measured. In addition to pressure sensing, this technology could be applied in detecting any polarization state change induced by magnetic fields, electric currents and so on.

Highlights

In the past two decades, fiber-optic sensors have attracted increasing attention in both the academic and industrial communities
A nano-wire grid fiber polarizer (NWGFP), which is a gold grid array fabricated on a fiber tip by a focused ion beam, was developed for sensing applications
Various approaches have been studied [10,11,12], in this paper we propose to fabricate a fiber polarizer making use of the characteristics of nano-wire grids

Summary

Introduction

In the past two decades, fiber-optic sensors have attracted increasing attention in both the academic and industrial communities. Waveguided or planar metamaterials which are composed of complimentary structures like nano-wire grids have been used to design optical components like filters, beam splitters, couplers, polarizers and interferometers [4,5,6]. A nano-wire grid fiber polarizer (NWGFP), which is a gold grid array fabricated on a fiber tip by a focused ion beam, was developed for sensing applications. A 13.7 dB reflection contrast and a 4.9 dB transmission contrast are experimentally obtained between TE and TM modes, which is sensitive enough to monitor tiny polarization changes in a fiber. Because of the transflective feature of NWGFP, the polarization states of both the transmissive and reflective lights in the fiber may be monitored simultaneously.

Nano-Wire Grid Polarizer

Experiments and Discussion

Findings

Conclusions