Postprint version. Published in IEEE Photonics Journal, Volume 3, Issue 6, December 1, 2011, pages 1206-1213.
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Transverse mode wavelength dependence in the gallium nitride (GaN) laser cavity is a new topic. Modal analysis simulations are run to optimize the blue GaN-based laser diode with a wavelength of 400, 430, and 460 nm. It is shown that the optical confinement factor (OCF) has a strong dependence on wavelength of emission and electron-block (e-block) thickness. The OCF can be changed from 4.9% at a 460-nm wavelength to 7.6% at 400 nm, which is a 55% difference. The effect of adding an e-block layer of different widths is also investigated with results showing that an e-block layer can change optical confinement by 14% at 460 nm wavelength and 13% at 400 nm wavelength. The bottom n-GaN layer thickness is optimized between 0.1 and 7 μm. It is found that a thin buffer layer improves optical mode distribution by reducing the ghost mode.