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Proceedings Paper

New self-consistent method for determining the coupling coefficient and the grating losses of DBR lasers using MATLAB
Author(s): Hoshin H. Yee; H.T. Hsu; J.Y. Chang; P.C. Chen
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Paper Abstract

In recent years, distributed feedback (DFB) or distributed- Bragg-reflector (DBR) lasers, with surface gratings situated on ridge waveguides, have been presented. Good properties of the latter, for instance, improved optical coupling and lowered threshold current, have been achieved for this type of laser. Based upon the stopband width measurement, the coupling coefficient of DFB lasers can be estimated with reasonable good accuracy. However, to characterize DBR lasers, many researchers have used the calculated coupling coefficient, since the stopband width from the reflectivity profile of the lasers is more difficult to clarify for this estimation compared to that of DFB lasers. It is especially true when grating losses due to scattering and absorption are large and difficult to measure for the surface-grating devices. In this case, estimation of the coupling coefficient becomes more problematic or even erroneous. This work used a novel method that involves implementing the relationship between the real and effective grating lengths and mode spacing under subthreshold to determine the coupling coefficient and grating losses of DBR lasers. Through a self-consistent approach, for the DBR lasers with a geometry of La equals 420 micrometers and Lg equals 380 micrometers , where La and Lg are the active-section and grating-section lengths, respectively, a coupling coefficient of 50 cm-1 and grating losses of 38 cm-1 at the lasing wavelength of 833 nm were estimated with a relatively good uncertainty of 10%.

Paper Details

Date Published: 2 February 2001
PDF: 10 pages
Proc. SPIE 4216, Optical Devices for Fiber Communication II, (2 February 2001); doi: 10.1117/12.414104
Show Author Affiliations
Hoshin H. Yee, National Taipei Univ. of Technology (Taiwan)
H.T. Hsu, National Taipei Univ. of Technology (Taiwan)
J.Y. Chang, National Taipei Univ. of Technology (Taiwan)
P.C. Chen, National Taipei Univ. of Technology (United States)

Published in SPIE Proceedings Vol. 4216:
Optical Devices for Fiber Communication II
Dilip K. Paul; Michel J. F. Digonnet; Osman S. Gebizlioglu; Osman S. Gebizlioglu; Roger A. Greenwell; Roger A. Greenwell; Dennis N. Horwitz; Dennis N. Horwitz; Dilip K. Paul, Editor(s)

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