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8 results on '"Wang, Cunda"'

1. Stimulated emission in GaN-based laser diodes far below the threshold region.

Author

Li, Ding, Zong, Hua, Yang, Wei, Feng, Liefeng, He, Juan, Du, Weimin, Wang, Cunda, Xie, Ya-Hong, Yang, Zhijian, Shen, Bo, Zhang, Guoyi, and Hu, Xiaodong

Subjects
Optical Physics, Electrical and Electronic Engineering, Communications Technologies, Optics
Abstract

We identify that the stimulated emission of GaN laser diodes (LDs) emerges far below the traditionally recognized threshold from both optical and electrical experiments. Below the threshold, the linear-polarized stimulated emission has been the dominating part of overall emission and closely related to resonant cavity. Its intensity increases super linearly with current while that of spontaneous emission increases almost linearly. Moreover, the separation of quasi-Fermi levels of electrons and holes across the active region has already exceeded the photon emission energy, namely, realized the population-inversion.

Published
2014

8. ENHANCEMENT OF THE REFLECTIVITY OF Co/C SOFT X-RAY MULTILAYERS AT GRAZING INCIDENCE BY THERMAL TREATMENT

Author

Bai Haili, Wang Cunda, Tian Ren-Yu, and Jiang Enyong

Subjects
Soft x ray, Materials science, Condensed matter physics, Annealing (metallurgy), business.industry, General Physics and Astronomy, Thermal treatment, Surface finish, First order, Enthalpy of mixing, Reflectivity, Condensed Matter::Materials Science, Wavelength, Optics, business
Abstract

We report a significant increase of the reflectivity of a soft X-ray Co/C multilayer at grazing incidence after low temperature annealing. By monitoring the enhancement of the first order modulation peak on annealing, the effective interdiffusion coefficient as low as -10－25ｍ2ｓ－1 has been measured,which is nearly equal to the true macroscopic interdiffusion coefficient as the modulation wavelength of the Co/C multilayer studied is well above the critical wavelength. The negative true macroscopic interdiffusion coefficient indicates that there is a tendency to phase separation in the Co-C system, which can be interpreted as the positive enthalpy of mixing calculated based on Miedema′s macroscopic atom model. The decrease of reflectivity above some anneal temperature is also discussed and explained as the competition between interfacial sharpness and roughness.

Published
1997

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