Coupled Local-Mode Theory for Strongly Modulated Long Period Gratings

Author

Jin, Long ; Jin, Wei ; Ju, Jian ; Wang, Yiping

Author_Institution

Dept. of Electr. Eng., Hong Kong Polytech. Univ., Hong Kong, China

Volume

28

Issue

12

fYear

2010

fDate

6/15/2010 12:00:00 AM

Firstpage

1745

Lastpage

1751

Abstract

A method for modeling the mode-coupling process in strongly modulated long period gratings (LPGs) is reported. The method is based on calculating the variations of local-mode profiles and propagation constants over the perturbed regions and solving the coupled local-mode equations to obtain a quantitative description of the intermodal energy exchange. The mode-coupling process and the spectral characteristics of a CO₂ laser-inscribed LPG in a photonic crystal fiber are numerically modeled and found in good agreement with the experimentally measured results. Compared with the methods based on the conventional coupled-mode and the mode-projection theories, the current method provides a more accurate description of the mode coupling process for LPGs with strong but slow-varying perturbations.

Keywords

coupled mode analysis; diffraction gratings; holey fibres; laser beam machining; optical fibre fabrication; photonic crystals; carbon dioxide laser; coupled local mode theory; local mode profile; mode coupling process; perturbed region; photonic crystal fiber; propagation constants; slow varying perturbation; strongly modulated long period gratings; Coupled local-mode theory; long period grating; photonic crystal fiber;

fLanguage

English

Journal_Title

Lightwave Technology, Journal of

Publisher

ieee

ISSN

0733-8724

Type

jour

DOI

10.1109/JLT.2010.2049252

Filename

5460986