DFB lasers with longitudinal variations in their grating pitch and, consequently, their Bragg wavenumber (corrugation-pitch-modulated or CPM-DFB) can achieve single-mode oscillation with good threshold gain margins and flatter longitudinal photon-density distributions than conventional quarter-wave-shift (QWS) DFB lasers. Moreover, substantial improvements of these two characteristics are provided by adequate variation of the coupling coefficient κ along the cavity In the paper, a three-section corrugation-pitch-modulated DFB laser with distributed-coupling-coefficient (DCC-CPM-DFB) is studied extensively. Threshold and above-threshold numerical simulations show that these structures can achieve very good single-mode operation by correct optimisation of the Bragg detuning and coupling strength profile at threshold and can maintain these characteristics up to high injection currents.
Threshold and above-threshold analysis of corrugation-pitch-modulated DFB lasers with inhomogeneous coupling coefficient
1997-12-01
12 pages
Article (Journal)
English
distributed feedback lasers , grating pitch , coupling strength profile , DFB lasers , Bragg wavenumber , longitudinal variations , coupled mode analysis , single-mode oscillation , inhomogeneous coupling coefficient , optical modulation , laser tuning , longitudinal photon-density distributions , above-threshold analysis , laser theory , correct optimisation , corrugation-pitch-modulated , corrugation-pitch-modulated DFB lasers , high injection currents , diffraction gratings , above-threshold numerical simulations , optimisation , three-section corrugation-pitch-modulated DFB laser , very good single-mode operation , Bragg detuning , laser modes , good threshold gain margins , distributed-coupling-coefficient
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