Femtosecond laser fabrication of long period fiber gratings and applications in refractive index sensing

✍ Scribed by Benye Li; Lan Jiang; Sumei Wang; Hai-Lung Tsai; Hai Xiao

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 490 KB
• Volume: 43
• Category: Article
• ISSN: 0030-3992
• DOI: 10.1016/j.optlastec.2011.04.011

✦ Synopsis

An improved point-by-point inscription method is proposed to fabricate long period fiber gratings (LPFGs) by using a laser operating at 800 nm with 35 fs duration pulses. The sensitivity to misalignment between the core and the focus is reduced by scanning a rectangular part on the fiber. LPFGs with an attenuation depth of 20 dB are achieved within the wavelength range of 1465-1575 nm. Characterization of the temperature sensitivity and thermal stability of the LPFGs is presented. A 5.6 nm wavelength shift and a 1.2 dB decrease in the attenuation peak are observed following heat treatment at 600 1C for 4 h. The fabricated LPFGs are used as refractive index sensors. The effect of heat treatment on the response of the LPFGs to refractive index changes is also studied.