Fabrication and Characterization of Current-injected Microdisk Lasers
Date Issued
2010
Date
2010
Author(s)
Hong, Jay-Zway
Abstract
Microdisk lasers play important roles of light sources with low power consumption in large-scale photonic integrated circuits. Microdisks whose cavities confine light to small volumes support high-Q whispering-gallery mode (WGM) resonances, so they are considered to be potential candidates for the next-generation semiconductor lasers used in optical long-distance telecommunications.
In this thesis, we fabricated two kinds of current-injected microdisk lasers- InGaAsP quantum-well and InGaAs quantum-dot microdisk lasers with disk size about 10μm in diameter. We measured the mode shift with varied temperature from 78K to room temperature.
We use InGaAsP quantum well samples to fabricate the electrically pumped microdisk laser devices, which can be further applied as laser sources in photonic integrated circuits. We have successfully fabricated disk lasers by e-beam lithography, ICP dry etching and selective wet etching techniques. Using a benzocyclobutene (BCB) polymer cladding which decreased redshift with varied temperature, the metal electrodes can be more easily made. We apply a DC current source for current injection. The threshold current is 28μA at 78K. The highest temperature where lasing can still be achieved is 250K. At this temperature, the threshold current for a 10-μm -diameter device was about 0.69 mA, and the Q factor is about 930.
We fabricated InGaAs QD microdisk lasers using two-steps wet etching to produce the double-disk structure. From the electroluminescence spectrum of our InGaAs QD microdisks by pulse current injection, we can get the lowest lasing threshold current at 150K. Below 150K, the characteristics temperature is negative. We can operate the device which lasing threshold current is 0.65mA at room temperature, and the largest WGM quality factor observed is 3700.
Subjects
microcavity
microdisk
threshold current
Q-factor
WGM
Type
thesis
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