| Records |
| Author |
Cao, Q.; Yoon, S. F.; Tong, C. Z.; Ngo, C. Y.; Liu, C. Y.; Wang, R.; Zhao, H. X. |
| Title |
Two-state competition in 1.3 μm multilayer InAs/InGaAs quantum dot lasers |
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Journal Article |
| Year |
2009 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl. Phys. Lett. |
Volume  |
95 |
Issue |
19 |
Pages |
3 |
| Keywords |
2DEG |
| Abstract |
The competition of ground state (GS) and excited state (ES) is investigated from the as-grown and thermally annealed 1.3 μm ten-layer p-doped InAs/GaAs quantum dot (QD) lasers. The modal gain competition between GS and ES are measured and analyzed around the ES threshold characteristics. Our results show that two-state competition is more significant in devices with short cavity length operating at high temperature. By comparing the as-grown and annealed devices, we demonstrate enhanced GS and suppressed ES lasing from the QD laser annealed at 600 °C for 15 s. |
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RPLAB @ gujma @ |
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673 |
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Kawamura, J.; Hunter, T. R.; Tong, C. Y. E.; Blundell, R.; Papa, D. C.; Patt, F.; Peters, W.; Wilson, T.; Henkel, C.; Goltsman, G.; Gershenzon, E. |
| Title |
Ground-based terahertz CO spectroscopy towards Orion |
Type |
Journal Article |
| Year |
2002 |
Publication |
A&A |
Abbreviated Journal |
A&A |
| Volume |
394 |
Issue |
1 |
Pages |
271-274 |
| Keywords |
HEB mixers, applications |
| Abstract |
Using a superconductive hot-electron bolometer heterodyne receiver on the 10-m Heinrich Hertz Telescope on Mount Graham, Arizona, we have obtained velocity-resolved 1.037 THz CO () spectra toward several positions along the Orion Molecular Cloud (OMC-1) ridge. We confirm the general results of prior observations of high-J CO lines that show that the high temperature, , high density molecular gas, , is quite extended, found along a ~ region centered on BN/KL. However, our observations have significantly improved angular resolution, and with a beam size of we are able to spatially and kinematically discriminate the emission originating in the extended quiescent ridge from the very strong and broadened emission originating in the compact molecular outflow. The ridge emission very close to the BN/KL region appears to originate from two distinct clouds along the line of sight with and ≈ . The former component dominates the emission to the south of BN/KL and the latter to the north, with a turnover point coincident with or near BN/KL. Our evidence precludes a simple rotation of the inner ridge and lends support to a model in which there are multiple molecular clouds along the line of sight towards the Orion ridge. |
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Ryabchun, S.; Tong, C.-yu E.; Blundell, R.; Kimberk, R.; Gol’tsman, G. |
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Effect of microwave radiation on the stability of terahertz hot-electron bolometer mixers |
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Conference Article |
| Year |
2006 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
| Volume |
6373 |
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Pages |
63730J (1 to 5) |
| Keywords |
NbN HEB mixers, hot-electron bolometer mixers, stability, Allan variance, LO power fluctuations |
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We report our studies of the effect of microwave radiation, with a frequency much lower than that corresponding to the energy gap of the superconductor, on the performance of the NbN hot-electron bolometer (HEB) mixer incorporated into a THz heterodyne receiver. It is shown that exposing the HEB mixer to microwave radiation does not result in a significant rise of the receiver noise temperature and degradation of the mixer conversion gain so long as the level of microwave power is small compared to the local oscillator drive. Hence the injection of a small, but controlled amount of microwave radiation enables active compensation of local oscillator power and coupling fluctuations which can significantly degrade the stability of HEB mixer receivers. |
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SPIE |
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Anwar, M.; DeMaria, A.J.; Shur, M.S. |
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Terahertz Physics, Devices, and Systems |
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1441 |
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