High-speed, high-power and high-efficiency photodiodes with evanescently coupled graded-index waveguide

2000 ◽  
Vol 36 (11) ◽  
pp. 972 ◽  
Author(s):  
T. Takeuchi ◽  
T. Nakata ◽  
K. Makita ◽  
M. Yamaguchi
Keyword(s):  
High Power ◽  
High Speed ◽  
High Efficiency ◽  
Graded Index

Ultrafast electron tunnelling in a reverse-biased, high-efficiency quantum well laser structure

1992 ◽  
Vol 70 (10-11) ◽  
pp. 985-992 ◽  
Author(s):  
D. P. Halliday ◽  
D. Moss ◽  
S. Charbonneau ◽  
G. C. Aers ◽  
D. Landheer ◽  
...  
Keyword(s):  
Quantum Well ◽  
High Speed ◽  
High Efficiency ◽  
Thermal Emission ◽  
Internal Quantum Efficiency ◽  
Thermionic Emission ◽  
Electron Recombination ◽  
Electron Level ◽  
Single Quantum Well ◽  
Graded Index

We have performed a detailed series of photoconductivity (PC) and photoluminescence (PL) measurements on a reverse-biased GaAs/AlGaAs single quantum well graded index separate confinement heterostructure laser. The PC was performed, as a function of bias, at room temperature on a high-speed ridge waveguide structure. The PL was performed at low temperatures (20, 70, and, 150 K) on a ring mesa sample as a function of bias. The measurements show that this device behaves as an extremely efficient high-speed photodetector with an internal quantum efficiency of 100% and a FWHM response time of 35 ps. The data is fitted using a simple model based on electron recombination in the quantum well or escape out of the well. The escape occurs by one of three possible routes: direct tunnelling out of the lower electron level, thermally assisted tunnelling through the upper electron level, or thermionic emission over the barrier. Each of these three terms is calculated theoretically. A comparison of theory and experiment leads us to the conclusion that the theories explaining thermal emission of carriers from a quantum well underestimate the lifetimes.

High Power Density and High Efficiency of High-Speed Motor

2020 ◽  
Author(s):  
Masato Enokizono ◽  
Daisuke Wakabayashi ◽  
Naoya Soda ◽  
Yuji Tsuchida ◽  
Shohei Ueno ◽  
...  
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
High Efficiency ◽  
High Power Density

Performance analysis of magnetic gear with Halbach array for high power and high speed

2020 ◽  
Vol 64 (1-4) ◽  
pp. 959-967
Author(s):  
Se-Yeong Kim ◽  
Tae-Woo Lee ◽  
Yon-Do Chun ◽  
Do-Kwan Hong
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
High Power ◽  
High Speed ◽  
Torque Ripple ◽  
Eddy Current Loss ◽  
Element Analysis ◽  
Current Loss ◽  
Halbach Array ◽  
Magnetic Gear

In this study, we propose a non-contact 80 kW, 60,000 rpm coaxial magnetic gear (CMG) model for high speed and high power applications. Two models with the same power but different radial and axial sizes were optimized using response surface methodology. Both models employed a Halbach array to increase torque. Also, an edge fillet was applied to the radial magnetized permanent magnet to reduce torque ripple, and an axial gap was applied to the permanent magnet with a radial gap to reduce eddy current loss. The models were analyzed using 2-D and 3-D finite element analysis. The torque, torque ripple and eddy current loss were compared in both models according to the materials used, including Sm2Co17, NdFeBs (N42SH, N48SH). Also, the structural stability of the pole piece structure was investigated by forced vibration analysis. Critical speed results from rotordynamics analysis are also presented.

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