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71.
Monolithic fabrication of a new distributed index planar microlens array by means of a deep electromigration technique in a glass substrate is reported. The array consists of distributed index lenses of 1.2 mm in diameter with 6.8 mm focal length. The focused spot is as small as 16 ?m for ?=0.63 ?m. The coupling efficiency of 60% to a multimode VAD fibre has been obtained. 相似文献
72.
The spontaneous emission factor (SEF) of a microcavity distributed Bragg reflector (DBR) surface-emitting laser has been obtained theoretically to investigate the possibility of the thresholdless lasing operation. Formulas expressing the spontaneous emission in a three-dimensional microcavity were obtained. By introducing the distribution of mode density in wavevector space, it is shown that the radiation pattern of spontaneous emission is deeply modified by the microcavity and is different from that in free space. Based on this result, the SEF and the emission lifetime are calculated as a function of emission spectral width and the size of the active region. It is found that the SEF exceeds 0.1, even though the spectral width is as large as 30 nm when the transverse size is smaller than 0.5 μm and the DBR reflectivity is larger than 90% 相似文献
73.
Yokouchi N. Miyamoto T. Uchida T. Inaba Y. Koyama F. Iga K. 《Photonics Technology Letters, IEEE》1992,4(7):701-703
Continuous tuning of 40 Å was achieved in a GaInAsP/InP vertical-cavity surface-emitting laser for the first time. The cavity length was directly changed by slightly moving an external mirror. The device was grown by chemical beam epitaxy (CBE) and the experiment was performed at low temperature. The result indicates that a short cavity structure can provide pure continuous wavelength tuning because of its wide longitudinal mode spacing 相似文献
74.
M Katashima T Irino F Shimojo A Kawamura H Kageyama N Higashi Y Miyao Y Tokuma T Hata K Yamamoto Y Sawada T Iga 《Canadian Metallurgical Quarterly》1998,63(3):354-366
Results from a comparative analysis of the efficiency of countermeasures in agriculture in a long term after the ChNPP accident are presented. Based on criteria such as reduction factor for 137Cs transfer to plants, averted dose and cost of 1 manSv relative ratings of countermeasures are given. Using one of the farms, located in the contaminated area as an example radiological justification of the optimal systems of countermeasures application is provided. 相似文献
75.
76.
In the letter the lasing characteristics of a multiquantum-well surface-emitting injection laser with 100 wells at 77 K under pulsed condition is reported. The output light of the device was linearly polarised.<> 相似文献
77.
Homem MG Iga I Sugohara RT Sanches IP Lee MT 《The Review of scientific instruments》2011,82(1):013109
In this work, we report an experimental investigation on relative flow-rate determination for vapors. The mechanism of adsorption-desorption of vapors on surfaces is considered. In contrast to previous investigations, our study shows that the adsorption of vapors on surfaces may significantly affect the flow-rate determination and consequently the measured cross sections. Particularly, for water, it can result in an overestimation of 35% in the cross sections. 相似文献
78.
79.
The ray-tracing method is applied to design a wavelength multiplexer-demultiplexer by the use of planar microlenses as focusing and collimating elements. By simulating both uniform and Gaussian intensity distributions of the input sources, we find the position of the input-output components of the wavelength multiplexe-rdemultiplexer, which maximizes the coupling efficiency in each channel. Losses are also evaluated. 相似文献
80.
Yuji Yamaguchi Dong Han Ha Fumitoshi Iga Yoshikazu Nishihara 《Journal of Superconductivity》1994,7(2):291-293
The ac susceptibility under a biased dc field near the irreversibility field (H
irr) of a Bi2Sr2CaCu2O8 single crystal has been measured. The frequency dependence, the ac-power dependence, and the nearly lossless character of the vs.H
dc curve forHa-axis have been roughly explained from a reversible (elastic) fluxoid motion, while those forH c-axis have been explained from a thermally assisted flux-flow (TAFF) model. The obtained parameters are discussed in relation to anisotropic flux-pinning mechanisms in the layered structure of this compound. 相似文献