The Characteristics of Optical Pumped GaN-Based Vertical Cavity Surface Emitting Laser Structures

Abstract:

Time-resolved photoluminescence spectra of vertical cavity surface emitting laser (VCSEL) structures under different excitation intensity are investigated. The effect of the distributed Bragg reflectors (DBR) on the laser emission and the mechanism of multi-longitudinal-mode are analysed. A broad peak around 2.80eV is observed from the structure without DBR cavity when pumped under low excitation intensity. At higher excitation density up to 21.4kW/cm², a lasing peak appears at 2.86eV, and exhibits a rapid growth and red shift with the increase of the excitation density. The decay time of the peak is about 66ps. When the spectrum is measured after the deposition of DBR on the top side of the grown nitride structure, the number of peaks increases to 7, and the free spectral range 0.21×10¹⁴ Hz is close to the value that calculated by the Fabry-Perot cavity length. After depositing the second DBR, multi PL peaks around 2.87eV are observed. The relationship of laser emission intensity and angle of the polarizer shows nearly a cosine square variation. However, the polarization characteristics of the four main peaks are different, which indicates that these peaks occurr by the oscillation of different optical cavities.

• Periodical: Applied Mechanics and Materials (Volume 692)
• Pages: 187-190
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.692.187
• Online since: November 2014
• Authors: Yi Ting He, Xiao Yan Lei, Zhi Ren Qiu*, Bao Ping Zhang, Na Lu, Ian T. Ferguson, Zhe Chuan Feng
• Keywords: GaN, Lifetime, Multimode, Optical Characteristics, Vertical Cavity Surface Emitting Laser

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