Axial profile of grating coupled radiation from second-order DFB lasers with phase shifts

Axial profiles of the grating-coupled radiation field emitted in a direction normal to the surface of distributed-feedback (DFB) lasers with phase-shifted second-order corrugation are theoretically analyzed. The profiles are calculated for nonreflecting DFB lasers with the following phase shifts: λ/4 shift, two lambda /8 shifts, and two 3 lambda /8 shifts. It is demonstrated that the radiation field can be controlled by changing the phase shifts. This result suggests a new method for modulating the surface emission of a DFB laser.