The crucial role of doping for high repetition rate monolithic modelocking of multiple quantum well GaAs/AIGaAs lasers

2005 ◽  
Author(s):  
S.D. McDougall ◽  
B. Vogele ◽  
C.R. Stanley ◽  
C.N. Ironside
Keyword(s):  
Quantum Well ◽  
Repetition Rate ◽  
Crucial Role ◽  
Multiple Quantum Well ◽  
High Repetition Rate ◽  
Multiple Quantum ◽  
High Repetition

Male and female responses to call playback in the Andean frog Colostethus subpunctatus

2002 ◽  
Vol 23 (2) ◽  
pp. 141-150 ◽  
Author(s):  
Horst Lüddecke
Keyword(s):  
Repetition Rate ◽  
Laboratory Experiments ◽  
Initial Rate ◽  
High Repetition Rate ◽  
Advertisement Call ◽  
Vocal Response ◽  
High Repetition ◽  
Female Responses ◽  
Aggressive Signals

AbstractBecause Colostethus subpunctatus males tend to aggregate, it is likely that calling neighbours communicate vocally. Males advertise by producing long series of short notes at regular intervals. Note repetition rates may vary individually. To determine whether the vocal response to playback of an individual's own advertisement call depended mainly on his initial note repetition rate or on temperature, I experimented with 49 isolated calling males under field conditions. Two different responses occurred. The response type was independent of initial note repetition rate and ambient temperature. Twenty-six males maintained the basic pattern of the advertisement call, but irrespective of temperature they significantly increased note repetition rate in correlation to the initial rate. Twenty-three males changed their call pattern by grouping 2-3 notes into a bout with much shorter silent intervals between notes. Bout repetition rate was also correlated with the initial note rate, but it was lower. To interpret the role of different call patterns, phonotaxis behaviour of twelve females was studied in two-choice laboratory experiments. Each female had the opportunity to choose four times between the advertisement call with low and high note repetition rate, and four times between the latter and the bout. Females tended to choose the high repetition rate more often than the low rate or the bout. The study provides support that an increase in note repetition rate gives competitive advantage to the caller in attracting a female. Bouts are probably aggressive signals used by a resident to repel intruders from his calling site.

Photoluminescence of InGaN/GaN and AlGaN/GaN multiple quantum well structures: role of depletion fields and polarization fields

2003 ◽  
Vol 195 (3) ◽  
pp. 523-527 ◽  
Author(s):  
B. Monemar ◽  
P. P. Paskov ◽  
H. Haratizadeh ◽  
P. O. Holtz ◽  
J. P. Bergman ◽  
...  
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Quantum Well Structures

Role of nonequilibrium carrier distributions in multiple quantum well InGaAsP-based lasers

1998 ◽  
Author(s):  
Mark S. Hybertsen ◽  
Muhammad A. Alam ◽  
Gene A. Baraff ◽  
Anatoly A. Grinberg ◽  
R. Kent Smith
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Nonequilibrium Carrier ◽  
Multiple Quantum

Photoluminescence of InGaN/GaN and AlGaN/GaN multiple quantum well structures: role of depletion fields and polarization fields

2003 ◽  
Vol 195 (3) ◽  
pp. 477-477
Author(s):  
B. Monemar ◽  
P. P. Paskov ◽  
H. Haratizadeh ◽  
P. O. Holtz ◽  
J. P. Bergman ◽  
...  
Keyword(s):  
Quantum Well ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Quantum Well Structures

Role of Localized Quantum Well Excitons in InGaN Quantum Well Structure Correlated with Microstructural Analysis

2000 ◽  
Vol 639 ◽  
Author(s):  
S. F. Chichibu ◽  
T. Sota ◽  
S. Nakamura
Keyword(s):  
Quantum Well ◽  
Microstructural Analysis ◽  
Multiple Quantum Well ◽  
Compositional Analysis ◽  
Diffraction Measurement ◽  
Multiple Quantum ◽  
X Ray Diffraction ◽  
Quantum Disk ◽  
Multiple Quantum Well Laser

ABSTRACTInxGa1−xN multiple-quantum-well laser diode structure, which lased at 405 nm, was shown to have atomically-flat interfaces between each layer. Nanometer-probe compositional analysis showed that InN mole fraction, x, in the wells and barriers are approximately 6 % and 2 %, respectively, which agreed with the result obtained from high-resolution x-ray diffraction measurement. The Stokes-like shift (SS) at 300 K was 49 meV, being approximately 65 % of the luminescence linewidth. The localization depth, E0, of qunatum-well (QW) excitons was estimated to be 35 meV at 300 K though the compositional fluctuation in the well was as small as 1 % or less (detection limit) within adjacent 20-30 nm lateral length scale. Since the well thickness fluctuation is insufficient to reproduce SS or E0, effective bandgap inhomogeneity is attributed to be due to large bandgap bowing in InGaN. The spontaneous emission was thus assigned as being due to the recombination of QW excitons weakly localized in exponential tail-type potential minima in the QW. The size of localization is smaller than the quantum-disk [M. Sugawara, Phys. Rev. B 51, 10743 (1995)]-size. Such small bandgap inhomogeneity can be leveled by injecting high density carriers under lasing conditions, which can explain the general experimental finding that the quantum efficiency decreases with increasing carrier density in InGaN QW devices due to free carrier trapping into threading dislocations.

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