Index-Antiguiding in Narrow-Ridge GaN-Based Laser Diodes Investigated by Measurements of the Current-Dependent Gain and Index Spectra and by Self-Consistent Simulation
L. Redaelli1,2, H. Wenzel1, J. Piprek3, T. Weig4, S. Einfeldt1, M. Martens5, G. Lükens4,6, U.T. Schwarz4,7, and M. Kneissl1,5
Published in:
IEEE J. Quantum Electron., vol. 51, no. 8, pp. 2000506 (2015).
Abstract:
The threshold current density of narrow (1.5 µm) ridge-waveguide InGaN multi-quantum-well laser diodes and the shape of their lateral far-field patterns strongly depend on the etch depth of the ridge waveguide. Both effects can be attributed to strong index-antiguiding. The value of the antiguiding factor R = 10 is experimentally determined near threshold by measurements of the current-dependent gain and refractive index spectra. The device performances are simulated self-consistently, solving the Schrödinger-Poisson equations and the equations for charge transport and waveguiding. Assuming a carrier-induced index change that matches the experimentally determined antiguiding factor, both the measured high-threshold current and the shape of the far-field pattern of lasers with shallow ridges can be reproduced theoretically.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
2 now with the French Alternative Energies and Atomic Energy Commission, Grenoble 38000, France
3 NUSOD Institute LLC, Newark, DE 19714 USA
4 Fraunhofer Institute for Applied Solid State Physics IAF, Freiburg 79108, Germany
5 Institute for Solid State Physics, Technische Universität Berlin, Berlin 10623, Germany
6 now with RTWH Aachen, Aachen 52074, Germany
7 Department of Microsystems Engineering, University of Freiburg, Freiburg 79110, Germany
Index Terms:
Diode lasers, gallium nitride, index-antiguiding, index change, lasing threshold, simulation.
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