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Effect of ridge waveguide etch depth on laser threshold of InGaN MQW laser diodes
- Source :
- Proceedings of SPIE.
- Publication Year :
- 2012
- Publisher :
- SPIE, 2012.
-
Abstract
- The laser threshold and lateral mode confinement of blue (440 nm) InGaN multiple quantum well (MQW) laser diodes have been investigated. Ridge-waveguide (RW) laser diodes with different ridge etch depth ranging from 25 nm above the active region (deep-ridge waveguide) to 200 nm above the active region (shallow-ridge waveguide) have been fabricated. The comparison of devices with the same resonator length shows that the threshold current densities are significantly lower for deep-ridge waveguide laser diodes. The difference in lasing threshold becomes more eminent for narrow ridges, which are required for single mode operation. For shallow-ridge devices the threshold current density increases by more than a factor of three when the ridge width is decreased from 20μm to 1.5μm. For the deep-ridge waveguide devices instead, the lasing threshold is almost independent of the ridge waveguide width. The effect has been analyzed by 2D self-consistent electro-optical simulations. For deep-ridge devices, the simulated thresholds and far-field patterns are in good agreement with the simulations. For shallow-ridge devices, however, questionable theoretical assumptions are needed. Two possible causes are discussed: extremely large current spreading and strong index anti-guiding.
Details
- ISSN :
- 0277786X
- Database :
- OpenAIRE
- Journal :
- Proceedings of SPIE
- Accession number :
- edsair.doi...........0c58dc8e33a3df191fd79d777cfe0afc