Surface-emitting, single-lobe operation from second-order distributed-reflector lasers with central grating phaseshift
Surface-emitting diode lasers containing a second-order Bragg grating with a central phaseshift, {Delta}{phi}, of values around {pi} are found to fundamentally favor lasing in a mode of symmetric near-field amplitude profile, which in turn provides emission in a single-lobed beam orthonormal to the surface. Devices of 500 {mu}m long distributed-feedback (DFB) active region ({lambda}=0.98{mu}m) and 500 {mu}m long distributed feedback reflector passive regions provide, for {Delta}{phi}={pi}, a surface-emitted beam pattern with 88% central-lobe power content, and external differential quantum efficiency, {eta}{sub D}, of 51%. Since the guided field is antisymmetric to start with, and a central {pi} phaseshift causes two grating-outcoupled beams to be out-of-phase with each other, the net result is a single-lobed far-field pattern. The guided-field peak-to-valley (intensity) ratio, R, in the active (i.e., DFB) region is only 2, which insures single-mode operation to high powers, since the intermodal discrimination is high ({ge}100 cm{minus}1). Over a wide range in {Delta}{phi}:60{degree}; {eta}{sub D} remains high ({gt}50%) and the degree of guided-field uniformity remains low (R{lt}2). {copyright} 2001 American Institute of Physics.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40204562
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 26 Vol. 78; ISSN 0003-6951
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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