Analysis of substrate modes in GaN/InGaN lasers

Bernd Witzigmann; Valerio Laino; Friedhard Roemer; Christoph Lauterbach; Ulrich T. Schwarz; Christian Rumbolz; Martin O. Schillgalies; Alfred Lell; Uwe Strauss; Volker Härle

doi:10.1117/12.700920

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23 March 2007 Analysis of substrate modes in GaN/InGaN lasers

Bernd Witzigmann, Valerio Laino, Friedhard Roemer, Christoph Lauterbach, Ulrich T. Schwarz, Christian Rumbolz, Martin O. Schillgalies, Alfred Lell, Uwe Strauss, Volker Härle

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Proceedings Volume 6468, Physics and Simulation of Optoelectronic Devices XV; 64680Q (2007) https://doi.org/10.1117/12.700920
Event: Integrated Optoelectronic Devices 2007, 2007, San Jose, California, United States

Abstract

In this contribution, substrate modes in edge-emitting lasers in the material system Gallium-Nitride are analyzed by means of comprehensive measurements and simulations. The simulations are complex vectorial optical mode calculations using a finite-element method. The simulation domain comprises the ridge waveguide and the full substrate with open boundary conditions on the sides. Therefore, the coupling mechanisms of the waveguides formed by the ridge and the substrate can be analyzed in a realistic setup. The characterization data include the optical loss spectrum obtained from Hakki-Paoli measurements, optical near field, and farfield measurements. The devices used for characterization are ridge waveguide quantum well lasers grown on GaN substrates. A comparison of the measurement data with the simulations explains the characteristics of the substrate modes in a consistent way, and shows very good agreement for the optical loss oscillations, farfield angle, and nearfield pattern. It is shown that material losses, material dispersion and optical diffraction are key ingredients for the analysis of substrate modes.

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Bernd Witzigmann, Valerio Laino, Friedhard Roemer, Christoph Lauterbach, Ulrich T. Schwarz, Christian Rumbolz, Martin O. Schillgalies, Alfred Lell, Uwe Strauss, and Volker Härle "Analysis of substrate modes in GaN/InGaN lasers", Proc. SPIE 6468, Physics and Simulation of Optoelectronic Devices XV, 64680Q (23 March 2007); https://doi.org/10.1117/12.700920

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