Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber

An asymmetric long period fiber grating (LPFG) with a large attenuation of -47.39 dB and a low insertion loss of 0.34 dB is fabricated by use of focused CO2 laser beam to carve periodic grooves on one side of the optical fiber. Such periodic grooves and the stretch-induced periodic microbends can effectively enhance the refractive index modulation and increase the average strain sensitivity of the resonant wavelength of the LPFG to -102.89 nm/m epsilon. The resonant wavelength and the peak attenuation of the LPFG can be tuned by similar to 12 nm and similar to 20 dB, respectively, by the application of a stretching force. (c) 2006 American Institute of Physics.