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Evaluation of Optical Confinement in GaN‐Based Lasing Structures
Author(s) -
Bidnyk S.,
Schmidt T.J.,
Song J.J.
Publication year - 1999
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199911)216:1<517::aid-pssb517>3.0.co;2-k
Subject(s) - lasing threshold , materials science , laser , optoelectronics , refractive index , total internal reflection , excitation , heterojunction , semiconductor laser theory , excited state , quantum dot , optics , diode , semiconductor , physics , atomic physics , quantum mechanics
We present a technique for evaluating optical confinement in GaN‐based lasing structures through their spectrally resolved near‐field pattern under high optical excitation. Emission spectra were found to be strongly dependent on the position of collection optics relative to the active region when the sample was excited above the lasing threshold. The spatially resolved spectra contain a modulation signature that can be used to deduce the optical confinement characteristics. We show that the observed index‐guided modes resulted from multiple internal reflections very near the critical angle of total internal reflection between the semiconductor layers with different refractive indices. This technique was used to evaluate the degree of optical confinement in GaN epilayers and GaN/AlGaN separate confinement heterostructure. The implications of this study on the design of GaN‐based laser diodes is discussed.