Reconstruction of long-period fiber gratings from their core-to-core transmission function

source: Β© 2006 Optical Society of America

In order to reconstruct the structure of a long-period grating, both the complex core-to-core transmission function and the complex core-to-cladding transmission function should be known. However, in practice, only the core-to-core transmission function of the grating can be measured. We demonstrate theoretically the reconstruction of long-period gratings from only the core-to-core transmission function. The reconstruction is performed by extracting the complex core-to-cladding transmission function of the grating from its core-to-core transmission function. Generally, the extraction is not unique; however, we show that by writing an additional grating in cascade to the interrogated grating, a unique reconstruction can be obtained. In weak long-period gratings, only the amplitude of the core-to-core transmission function is needed to reconstruct the grating. The results of our work can enable the experimental reconstruction of long-period gratings from their transmission function as well as the development of novel distributed sensors.Β [Read more…]

Fig. 1 Schematic description of the grating structure analyzed in the paper. Two cascaded LPGs with lengths 𝐿1 and 𝐿2 are separated by a gap with a length 𝐿𝑓 . The fields of the core mode and cladding mode at the input end of the structure are denoted by 𝑒2(π‘˜,𝑧=0) and 𝑒1(π‘˜,𝑧=0) , respectively. The core-to-core and core-to-cladding transmission functions of the first grating are denoted by π‘Ž1(π‘˜) and 𝑏1(π‘˜) , respectively, and the core-to-core and core-to-cladding transmission functions of the total structure are denoted by π‘Žtor(π‘˜) and 𝑏tot(π‘˜) , respectively.

Amir Rosenthal and Moshe Horowitz, “Reconstruction of long-period fiber gratings from their core-to-core transmission function,” J. Opt. Soc. Am. A 23, 57-68 (2006)