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Improved ground-state modulation characteristics in 1.3 μm InAs/GaAs quantum dot lasers by rapid thermal annealing.

Zhao H, Yoon SF, Ngo CY, Wang R - Nanoscale Res Lett (2011)

Bottom Line: The choice of annealing conditions was determined from our recently reported results.With reference to the as-grown QD lasers, one obtains approximately 18% improvement in the modulation bandwidth from the annealed QD lasers.In addition, the modulation efficiency of the annealed QD lasers improves by approximately 45% as compared to the as-grown ones.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore. zhao0097@e.ntu.edu.sg.

ABSTRACT
We investigated the ground-state (GS) modulation characteristics of 1.3 μm InAs/GaAs quantum dot (QD) lasers that consist of either as-grown or annealed QDs. The choice of annealing conditions was determined from our recently reported results. With reference to the as-grown QD lasers, one obtains approximately 18% improvement in the modulation bandwidth from the annealed QD lasers. In addition, the modulation efficiency of the annealed QD lasers improves by approximately 45% as compared to the as-grown ones. The observed improvements are due to (1) the removal of defects which act as nonradiative recombination centers in the QD structure and (2) the reduction in the Auger-related recombination processes upon annealing.

No MeSH data available.


Related in: MedlinePlus

The frequency response of a 1-mm long as-grown QD laser measured at 10°C.
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Figure 1: The frequency response of a 1-mm long as-grown QD laser measured at 10°C.

Mentions: Figure 1 shows the frequency response of the as-grown device with cavity length of 1 mm, measured at 10°C. The threshold current (Ith) of the as-grown device is approximately 51.6 mA. The bandwidth increases gradually with bias currents. The maximum bandwidth obtained is 7.73 GHz. Figure 2 shows the lasing spectra of the same as-grown QD laser at 10°C measured at (a) 280 mA, and (b) 290 mA.. Note that the ES lasing threshold (Ith,ES) of the as-grown device is 284 mA. At the bias current of 5.9 × Ith (280 mA), the laser emission wavelength is approximately 1319 nm and corresponds to the GS lasing (refer to Figure 2a). When increasing the bias current to 6.1 × Ith (290 mA), emission wavelengths of approximately 1227 and 1320 nm exist simultaneously (refer to Figure 2b). The energy separation between the two states is approximately 71 meV. Thus, in the as-grown laser, GS lasing dominates at low bias currents, while ES lasing dominates at higher bias currents. The bandwidth of 7.73 GHz for the as-grown device measured at 290 mA includes the contribution from ES lasing. The bandwidth obtained from purely GS lasing is 6.95 GHz at 280 mA. Slight increase of the bias current by 10 mA causes a significant increase of bandwidth by 0.78 GHz (from 6.95 to 7.73 GHz), which is likely due to the additional photons emitted by the ES lasing. However, the bandwidth contributed by ES lasing is undesired since the wavelength of interest for telecommunication is 1.3 μm.


Improved ground-state modulation characteristics in 1.3 μm InAs/GaAs quantum dot lasers by rapid thermal annealing.

Zhao H, Yoon SF, Ngo CY, Wang R - Nanoscale Res Lett (2011)

The frequency response of a 1-mm long as-grown QD laser measured at 10°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211475&req=5

Figure 1: The frequency response of a 1-mm long as-grown QD laser measured at 10°C.
Mentions: Figure 1 shows the frequency response of the as-grown device with cavity length of 1 mm, measured at 10°C. The threshold current (Ith) of the as-grown device is approximately 51.6 mA. The bandwidth increases gradually with bias currents. The maximum bandwidth obtained is 7.73 GHz. Figure 2 shows the lasing spectra of the same as-grown QD laser at 10°C measured at (a) 280 mA, and (b) 290 mA.. Note that the ES lasing threshold (Ith,ES) of the as-grown device is 284 mA. At the bias current of 5.9 × Ith (280 mA), the laser emission wavelength is approximately 1319 nm and corresponds to the GS lasing (refer to Figure 2a). When increasing the bias current to 6.1 × Ith (290 mA), emission wavelengths of approximately 1227 and 1320 nm exist simultaneously (refer to Figure 2b). The energy separation between the two states is approximately 71 meV. Thus, in the as-grown laser, GS lasing dominates at low bias currents, while ES lasing dominates at higher bias currents. The bandwidth of 7.73 GHz for the as-grown device measured at 290 mA includes the contribution from ES lasing. The bandwidth obtained from purely GS lasing is 6.95 GHz at 280 mA. Slight increase of the bias current by 10 mA causes a significant increase of bandwidth by 0.78 GHz (from 6.95 to 7.73 GHz), which is likely due to the additional photons emitted by the ES lasing. However, the bandwidth contributed by ES lasing is undesired since the wavelength of interest for telecommunication is 1.3 μm.

Bottom Line: The choice of annealing conditions was determined from our recently reported results.With reference to the as-grown QD lasers, one obtains approximately 18% improvement in the modulation bandwidth from the annealed QD lasers.In addition, the modulation efficiency of the annealed QD lasers improves by approximately 45% as compared to the as-grown ones.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore. zhao0097@e.ntu.edu.sg.

ABSTRACT
We investigated the ground-state (GS) modulation characteristics of 1.3 μm InAs/GaAs quantum dot (QD) lasers that consist of either as-grown or annealed QDs. The choice of annealing conditions was determined from our recently reported results. With reference to the as-grown QD lasers, one obtains approximately 18% improvement in the modulation bandwidth from the annealed QD lasers. In addition, the modulation efficiency of the annealed QD lasers improves by approximately 45% as compared to the as-grown ones. The observed improvements are due to (1) the removal of defects which act as nonradiative recombination centers in the QD structure and (2) the reduction in the Auger-related recombination processes upon annealing.

No MeSH data available.


Related in: MedlinePlus