Realization of Long Period Fiber Grating in Reflection Mode Operating Near Turn Around Point

A method of fabrication of a reflection-type long-period fiber grating (LPFG) operating near turn around point has been presented along with theoretical details. We have shown that removal of multiple resonant bands due to unwanted phase shift introduced after cleaving the grating at an arbitrary location can be accomplished by tailoring the phase matching curve of the cladding mode. This also allows us to enhance the sensitivity of the sensor. The grating can be cleaved at any arbitrary location within the grating structure. Therefore, the probe-type sensor head can be made considerably small. We have presented performance characteristics in detail. The sensitivity of the device has been found to be ~1300 nm/RIU and is superior to majority of the reflection-type LPFG sensors where mostly lower order cladding modes were considered.