ANTIPHASE COMPLEX-COUPLED SURFACE-EMITTING DISTRIBUTED-FEEDBACK DIODE-LASERS WITH ABSORPTIVE GRATINGS

Theoretical analysis of antiphase-type complex-coupled, surface-emitti ng distributed feedback (CC-SE-DFB) diode lasers with absorptive grati ngs is presented and discussed. Two different designs are studied: one utilizing a semiconductor-based second-order loss and index grating p laced at the metal-semiconductor (p-side) interface, and the other emp loying a combination of metallic and semiconductor materials for the s econd-order loss and index grating, For certain design parameters, the se two types of absorptive-grating structure are shown to select lasin g in the symmetric mode (i.e., orthonormal emission in a single-lobe b eam pattern). By comparison to metal-grating surface-emitting devices, the threshold gains for these structures are lower by factor of 3 to 4, For 500-mu m-long gratings, the symmetric-mode is favored to lase w ith threshold gain values as low as 18 cm(-1) and differential quantum efficiency as high as 34%.