Analysis of radiation mode effects on oscillating properties of DFBlasers

摘要

The effects of radiation mode on the oscillating properties ofndistributed feedback (DFB) lasers with second-order corrugations arenanalyzed for designing a new type of DFB laser. A formulation based onnthe transfer matrix technique is applied to calculating Streifer'snΖ-terms added to the coupled-wave equations. These terms representnthe effects of radiation and evanescent modes. This formulation greatlynsimplifies the analysis of distributed resonance along multilayerednwaveguide structures with arbitrary-shaped second-order corrugations.nThe effects of vertical resonance are also incorporated into thenformulation. Various types of DFB lasers with phase-shifted second-orderncorrugations are analyzed using this method. It is found that the phasenshift and the blaze of the corrugations greatly affect the longitudinalnmode selectivity. A new phase-shift DFB laser structure with twoncomplementary blazing regions connected at the shift is proposed. It isndemonstrated that this structure has small radiation loss resulting innlow-threshold performance despite employing second-order corrugations