Abstract
Ultrasmall microring and microdisk lasers with an asymmetric air/GaAs/Al0.98Ga0.02As waveguide and an active region based on InAs/InGaAs/GaAs quantum dots emitting around 1.3 μm were fabricated and studied. The diameter D of the microrings and microdisks was either 2 or 1.5 μm, and the inner diameter d of the microrings varied from 20% to 70% of the outer diameter D. The microring with D = 2 μm and d = 0.8 μm demonstrated a threshold pump power as low as 1.8 μW at room temperature. Lasing was observed up to 100°C owing to the use of quantum dots providing high confinement energy both for electrons and holes. Tuning spectral positions of the whispering gallery modes via changing the inner diameters of the microrings was demonstrated.PACS78.67.Hc; 42.55.Sa; 42.50.Pq; 78.55.CrElectronic supplementary materialThe online version of this article (doi:10.1186/1556-276X-9-657) contains supplementary material, which is available to authorized users.
Highlights
Semiconductor microdisks (MDs) and microrings (MRs) are presently attracting increasing attention as key elements of future photonic integrated circuits
We present the results on elevated temperature lasing of quantum dots (QDs) MDs and MRs with diameters as small as 1.5 to 2 μm on a semiconductor pedestal
The active region comprised five layers of InAs/In0.15Ga0.85As/ GaAs QDs separated with 35-nm-thick GaAs spacers
Summary
Semiconductor microdisks (MDs) and microrings (MRs) are presently attracting increasing attention as key elements of future photonic integrated circuits. They can be used as low-threshold microlasers [1,2], modulators [3], add/drop filters [4], etc. Fabrication of small-sized (of the order of charge carrier diffusion length) microcavities is challenging. This is because etching used for the fabrication, being performed through the active region, can result in non-radiative recombination of the carriers at the processed surfaces. This issue is especially crucial for the GaAs-based material system where the surface recombination rate is an order of magnitude higher than in the InP-based materials [5]
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