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91.
By three-dimensional kinetic Monte Carlo simulations, the effects of the temperature, the flux rate, the total coverage and the interruption time on the distribution and the number of self-assembled InAs/GaAs(001) quantum dot(QD) islands are studied, which shows that a higher temperature, a lower flux rate and a longer growth time correspond to a better island distribution. The relations between the number of islands and the temperature and the flux rate are also successfully simulated. It is observed that for the total coverage lower than 0.5 ML, the number of islands decreases with the temperature increasing and other growth parameters fixed and the number of islands increases with the flux rate increasing when the deposition is lower than 0.6 ML and the other parameters are fixed. 相似文献
92.
Zero dispersion wavelength and dispersion slope control of hollow-core photonic bandgap fibres 下载免费PDF全文
This paper investigates the zero dispersion wavelength and
dispersion slope control of hollow-core photonic bandgap fibres
(PBGFs) by using a full-vector finite element method. By simulation
we found that theoretically the zero dispersion wavelength can be
tailored by respectively changing the rounded diameter of air holes,
pitch, refractive index, normalized thickness of core rings, and
hole diameter to pitch ratio. At the same time the tailoring of
dispersion slope can also be realized by changing the rounded diameter
of air holes or pitch or normalized thickness of core rings. To
illustrate the reasonability of fibre designs, this paper also gives
the variance of normalized interface field intensity which measures
the scattering loss relatively versus wavelength for different
designs. From the viewpoint of loss, varying the rounded diameter
and the thickness of core ring could shift zero wavelength but it is
difficult to get the required parameters within so tiny range in
practical drawing of PBGFs, on the other hand, it is possible in
practice to respectively alter the pitch and refractive index to
shift zero wavelength. But varying hole diameter to pitch ratio is
not worthwhile because they each induce large increase of loss and
narrowness of transmission bandwidth. The zero dispersion wavelength
can be engineered by respectively varying the rounded diameter of air
holes, pitch, refractive index, and normalized thickness of core
rings without incurring large loss penalties. 相似文献
93.
The band structures of rectangular GaN/AlGaN quantum wires are modeled by using a parabolic effective-mass theory.The absorption coefficients are calculated in a contact-density matrix approach based on the band structure.The results obtained indicate that the peak absorption coefficients augment with the increase of the injected carrier density,and the optical gain caused by interband transition is polarization anisotropic.For the photon energy near 1.55 eV,we can obtain relatively large peak gain.The calculations support the previous results published in the recent literature. 相似文献
94.