Dielectric Microdisks with Embedded CdSe/ZnS Colloidal Quantum Dots for Laser Applications
Date Issued
2012
Date
2012
Author(s)
Lin, Chia-Hung
Abstract
In this thesis, dielectric microdisk resonators embedded with CdSe/ZnS colloidal quantum dots were demonstrated in the visible range of 600 nm. We fabricated silicon dioxide microdisks embedded with CdSe/ZnS colloidal quantum dots with diameters of 8 μm and 10 μm, respectively. Lasing has been observed for the 10-μm-diameter microdisk resonator, and the quality factor and the threshold pump power are about 3,100 and 85 μW, respectively.
Since silicon nitride has higher refractive index than silicon dioxide, better optical confinement and higher quality factor can be expected in silicon nitride microdisk resonators. However, silicon nitride microdisk resonators could be damaged with excessive pump power. The problem can be relieved by decreasing the flow rate of silane in the silicon nitride deposition process at the cost of lowering refractive index. The quality factor of a 4-μm-diameter microdisk resonator with silane flow rate of 125 sccm is about 1,000. For microdisk resonators with silane flow rate of 76 sccm, whispering gallery modes can also be observed for diameters of 6 μm and 8 μm, and the quality factors are about 400. We also discuss and improve the fabrication process to achieve better measurement results.
Subjects
microdisk
CdSe/ZnS colloidal quantum dots
Type
thesis
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