• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.298-305
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• 2003

We have calculated the single mode yield of index-coupled (IC) DFB lasers above threshold for several kL, and facet reflectivity combinations, and investigated the correlation between those results and the single mode yield as a function of f number at the threshold. As a result, there is little correlation between the single mode yield above threshold and the single mode yield as a function of f number at the threshold. The single mode yields above threshold for kL of 0.8 and 1.25 is larger than those for kL, of 2 and 3 due to the spatial hole burning effect. Also, we have investigated the effect of the reflectivity of the AR facet on the single mode yield for AR-HR and AR-CL combinations. For AR-HR combinations, the single mode yield increases as the reflectivity of the AR facet decreases. However, for AR-CL combinations, the reflectivity of the AR facet for the largest single mode yield exists. In the single mode yield calculations for IC DFB lasers in this paper, the single mode yield for kL of 0.8 with AR(1％)-HR combination is largest above threshold.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.413-422
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• 2003

We have calculated the power extraction efficiency and the lasing wavelength distribution of index-coupled DFB lasers at threshold for various kL and facet reflectivity combinations, and compared with those above-threshold. The power extraction efficiency increases as the asymmetry of the facet reflectivities increases. The power extraction efficiency above-threshold is slightly larger than that at threshold. Since the relative photon density around the center region increases as kL increases, the power extraction efficiency decreases. The uniformity of the distribution of lasing wavelength over the stop band increases due to the relief of mode degeneracy as the asymmetry of the facet reflectivities increases. In the case of AR-HR combination, the lasing wavelength distributions at threshold are similar to those above-threshold. However, in the case of AR-AR combination, the lasing wavelength at threshold is concentrated on both edges of the stop band, while it is concentrated only on the longer wavelength edge above-threshold. As kL increases, the range of the lasing wavelength distribution increases due to the increase of the stop band. The effect of AR reflectivity on the power extraction and the lasing wavelength distribution is very weak.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.548-555
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• 2006

We investigate the effect of the reflectivity of both facets and the phase of a phase tuning section on the self-pulsation (SP) characteristics of multisection index-coupled (IC) DFB lasers composed of two index-coupled DFB sections and a phase tuning section between them in terms of yield. In the case of weak coupling strength, as the reflectivity of both facets increases, the effect of reflected fields from both facets and the other DFB section on the mode characteristics of one DFB section increases. Thus the number of mode hoping increases and yield decreases for the variation of phases of both facets. In the case of strong coupling strength, as the reflectivity of both facets increases, the spatial hole burning effect increases, so that the yield decreases. The maximum yield and the range of the phase of a phase tuning section with yield more than 40% decrease as the facet reflectivity increases irrespective of coupling strength. As the coupling strength increases, the variation of yield for the variation of the phase of a phase tuning section increases and the variation of the phase of a phase tuning section with the maximum yield for the variation of the reflectivity of both facets decreases. The yield characteristics of the cases with the coupling strengths of 2 and 3 are better than those with the coupling strengths of 1.2 and 4.