Direct Measurement Of Leakage Currents In Long-Wavelength Buried Heterostructure Lasers

1986 ◽  
Author(s):  
P. I. Kuindersma ◽  
A. Valster
Keyword(s):  
Direct Measurement ◽  
Leakage Currents ◽  
Long Wavelength ◽  
Buried Heterostructure

Direct measurement of lateral carrier leakage in 1.3-/spl mu/m InGaAsP multiple-quantum-well capped mesa buried heterostructure lasers

2002 ◽  
Vol 38 (9) ◽  
pp. 1276-1281 ◽  
Author(s):  
G. Belenky ◽  
L. Shterengas ◽  
C.L. Reynolds ◽  
M.W. Focht ◽  
M.S. Hybertsen ◽  
...  
Keyword(s):  
Quantum Well ◽  
Direct Measurement ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Buried Heterostructure

Defect Mechanisms in Degradation of Long Wavelength (1.30–1.55 Micron) Laser Diodes

1990 ◽  
Vol 184 ◽  
Author(s):  
S. N. G. Chu
Keyword(s):  
Active Region ◽  
Laser Diodes ◽  
Normal Operation ◽  
Nonradiative Recombination ◽  
Dislocation Loops ◽  
Dark Line ◽  
Long Wavelength ◽  
Structural Deterioration ◽  
Extrinsic Dislocation ◽  
Buried Heterostructure

ABSTRACTOptical degradation of long wavelength (1.30–1.55 micron) laser diodes during normal operation or accelerated aging test caused by lattice structural deterioration of the active region materials and mirror facet damage were investigated in detail. Extrinsic dislocation loops of 1/2<100>{010) types were observed in gradually degraded channeled-substrate-buried-heterostructure (CSBH) lasers. These dislocation loops, originated at the sidewall interfaces outside the active region, grew into the active region in the direction of minority carrier injection. A great enhancement of the loops' growth rate was observed after they entered the active region, indicating a nonradiative recombination enhanced defect reaction under the strong optical field. Furthermore, the <100> oriented extrinsic dislocation loops were confirmed to be dark-line-defects (DLDs). On the other hand, strong nonradiative recombination centers, created by mirror facet damage, or pre-existed internally inside the cavity, resulted localized melting on the {111} planes. The propagation of the localized melt-patch along the laser beam direction created a wormlike defect along the laser cavity, which degraded the laser device catastrophically. Various types of grown-in defects for CSBH and etched-mesa-buried-heterostructure (EMBH) laser devices are described and their effects on the device performance are demonstrated.

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

Direct Measurement of the Listening of Hearing-Impaired Children

1970 ◽  
Vol 13 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Mary Mira
Keyword(s):  
Direct Measurement ◽  
Continuous Measurement ◽  
Hearing Impaired ◽  
Reinforcement System ◽  
School Aged Children ◽  
Conjugate Reinforcement ◽  
Impaired Children ◽  
Hearing Impaired Children

Listening, a significant dimension of the behavior of hearing-impaired children, may be measured directly by recording childrens' responses to obtain audio narrations programmed via a conjugate reinforcement system. Twelve hearing-impaired, school-aged children responded in varying ways to the opportunity to listen. Direct and continuous measurement of listening has relevance for evaluation of remediation methods and for discovery of variables potentially related to listening.

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