Flat-top and ultranarrow bandpass filter designed by sampled fiber Bragg grating with multiple equivalent phase shifts

Xihua Zou; Fei Wang; Wei Pan

doi:10.1364/ao.48.000691

Flat-top and ultranarrow bandpass filter designed by sampled fiber Bragg grating with multiple equivalent phase shifts

Appl Opt. 2009 Feb 1;48(4):691-4. doi: 10.1364/ao.48.000691.

Authors

Xihua Zou¹, Fei Wang, Wei Pan

Affiliation

¹ School of Information Science and Technology, Southwest Jiaotong University, Chengdu, 610031, China. zouxh_swjtu@yahoo.com.cn

PMID: 19183594
DOI: 10.1364/ao.48.000691

Abstract

We propose a novel approach to designing an optical filter with a flat-top and ultranarrow transmission band by using a sampled fiber Bragg grating (SFBG) having multiple equivalent phase shifts (EPSs). In the proposed approach, multiple EPSs are fabricated by adjusting several sampling periods of the SFBG. The obtained multiple EPSs are then arranged properly to get a flat-top transmission band in the narrow -1st reflection band of the SFBG, leading to the generation of a flat and ultranarrow transmission band. Filters with two or five EPSs are designed by simulation and experiment, with low ripples and ultranarrow 1 dB bandwidths observed in transmission bands.