Tag: 2006

source: © 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. [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 𝑢2(𝑘,𝑧=0) and 𝑢1(𝑘,𝑧=0) , respectively. The core-to-core and core-to-cladding transmission functions of the first grating are denoted by 𝑎1(𝑘) and 𝑏1(𝑘) , respectively, and the core-to-core and core-to-cladding transmission functions of the total structure are denoted by 𝑎tor(𝑘) and 𝑏tot(𝑘) , 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)

source: © 2006 Optical Society of America

We demonstrate a novel split-step solution for analyzing nonlinear fiber Bragg gratings. The solution is used for designing nonlinear fiber Bragg gratings with a low reflectivity. The structure of the grating is designed according to the profiles of the incident and reflected pulses. We demonstrate our method for nonlinear compression of a pulse reflected from a fiber Bragg grating. The method allows us to obtain compressed pulses with a very low wing intensity. [Read more…]

Fig. 2 Schematic description of optical pulse compression geometry.

Amir Rosenthal and Moshe Horowitz, “Analysis and design of nonlinear fiber Bragg gratings and their application for optical compression of reflected pulses,” Opt. Lett. 31, 1334-1336 (2006)

source: ©2006 American Physical Society

We present a method for efficiently exciting a Bragg soliton with a spectral content located mostly within the bandgap of a one-dimensional periodic structure. The method is based on a new interaction between Bragg solitons and on a high intensity enhancement, caused owing to the reduced propagation velocity inside periodic structures. Our method can also be used for efficient compression of optical pulses. We have theoretically demonstrated pulse compression with a compression ratio of 2800—over two orders of magnitude higher than previously reported. The results open new possibilities for experimental demonstration of Bragg soliton propagation and for pulse compression in one-dimensional periodic structures. [Read more…]

Fig. 1 Bandgap diagram of the grating. The grating is divided into three sections. In the first section, the slow-light effect is used to enhance the pulse intensity. In the second region, a soliton interaction is used to form a single in-gap soliton. In the third region, the soliton is compressed owing to the shifting of the bandgap.

Amir Rosenthal and Moshe Horowitz, “Bragg-soliton formation and pulse compression in a one-dimensional periodic structure,” Phys. Rev. E 74, 066611 (2006)