Design of High Slope-Efficiency Phase-Shifted DFB Laser Diodes with Asymmetrically-Pitch-Modulated (APM) Gratings

Kenji SATO  Yoshiharu MUROYA  Tetsuro OKUDA  

IEICE TRANSACTIONS on Electronics   Vol.E83-C   No.6   pp.855-859
Publication Date: 2000/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Optical Devices for Next Generation High-Speed Communication Systems and Photonic Networks)
Category: Semiconductor Lasers
phase-shifted DFB laser diode,  chirped grating,  slope efficiency,  single mode yield,  

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A theoretical study on high slope-efficiency phase-shifted DFB laser diodes is presented. We have proposed a new grating structure called asymmetrically-pitch-modulated (APM) grating, and calculated its slope- efficiency and single-mode-yield. In order to take into account the modulated grating period; we have developed an F-matrix which directly includes a chirped grating structure. APM phase-shifted DFB laser diodes consist of a uniform grating in one half section of the cavity and a chirped grating in the other half. This structure causes asymmetrical field distribution inside the cavity and the optical output power from one facet is larger than that from the other facet. According to the simulation results, when the normalized coupling coefficient κ L is 3.0, the front-to-rear output power ratio is 2.6, while the single-mode-yield remains at 100%, and simultaneously the slope-efficiency improvement becomes 65% better than that of ordinary quarter-wave phase-shifted DFB lasers of the same κ L value.