Tunable optical narrowband filter using a gain-coupled phase-shift-controlled distributed feedback laser

• Published in: IEEE journal of selected topics in quantum electronics 2005-09, Vol.11 (5), p.913-918
• Main Authors: Kian Yong Lim, Low, A.L.Y., Su Fong Chien, Ghafouri-Shiraz, H.
• Format: Article
• Language: English
• Subjects: Band pass filters; Channels; Deviation; Diode lasers; Distributed feedback (DFB) lasers; Distributed feedback devices; Equations; Gain; gain coupled; Laser feedback; Laser tuning; Mathematical analysis; Narrowband; Optical feedback; Optical filters; Quantum electronics; semiconductor lasers; transfer matrix method; Tunable circuits and devices; tunable optical filters; Tuning; Wavelengths
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2005.854151

In this paper, we have proposed and analyzed a new tunable optical narrowband filter using gain-coupled phase-shift-controlled distributed feedback (GC-PSC-DFB) laser diode. Coupled-mode equations are solved by using the transfer matrix method (TMM). The GC-PSC-DFB filters offer a stable single-mode bandpass output, similar to that obtained with phase-shifted index-coupled structures. However, GC structures do not suffer from the severe longitudinal spatial hole burning (SHB) that occurs in high-coupling quarter-wave-shifted DFB filters. This SHB can cause multimoded behavior for high-input signal power. Various filter parameters such as wavelength tuning range, side-mode suppression ratio (SMSR), and channel gain deviation have been investigated and discussed. Our results show that the GC DFB structures offer a wider tuning range of 23.3 /spl Aring/ compared with the similar index-coupled DFB structures with nearly steady bandwidth of 12 GHz, while maintaining 41.8-dB constant gain.