Low-cost fiber optic devices and sensors based on long-period fiber gratings written by high-frequency CO<sub>2</sub> laser pulses

Yun-Jiang Rao

doi:10.1117/12.635388

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5 December 2005 Low-cost fiber-optic devices and sensors based on long-period fiber gratings written by high frequency CO₂ laser pulses

Yun-Jiang Rao

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Proceedings Volume 6019, Passive Components and Fiber-based Devices II; 601921 (2005) https://doi.org/10.1117/12.635388
Event: Asia-Pacific Optical Communications, 2005, Shanghai, China

Abstract

In this paper, we report novel long-period fiber gratings (LPFGs) fabricated by using a new writing technique that is mainly based on the thermal shock effect of focused high-frequency CO₂ laser pulses at several kHz. Based on these novel LPFGs, an amplified spontaneous emission (ASE) noise filter and a gain equalizer have been demonstrated for the noise reduction and the gain spectrum flattening of Er-doped fiber amplifiers (EDFAs), respectively. By use of the unique bending, twisting and loading features of the LPFG, three tunable gain equalizers have been demonstrated for dynamic gain flattening of EDFAs. In addition, a number of novel fiber-optic sensors, including a bend-insensitive LPFG sensor that could solve the problem of cross-sensitivity between bend and other measurands, a torsion sensor that can realize absolute measurement of twist rate, and a load sensor that can achieve simultaneous measurement of transverse load and temperature using a single LPFG element are proposed and demonstrated. The unique features of these LPFGs are mainly due to the asymmetrical distribution of the refractive index on the cross-section of the LPFG induced by high-frequency CO₂ laser pulses.

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Yun-Jiang Rao "Low-cost fiber-optic devices and sensors based on long-period fiber gratings written by high frequency CO₂ laser pulses", Proc. SPIE 6019, Passive Components and Fiber-based Devices II, 601921 (5 December 2005); https://doi.org/10.1117/12.635388

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