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171.
We propose to approximate a spherically symmetric Bragg resonator in an onionlike geometry. We develop a transfer-matrix theory for calculation of the quality factors and analyze the effect of the onion stem on cavity Q factors. We find that it is possible to achieve significant inhibition of spontaneous emission in an onion resonator with omnidirectional cladding layers. 相似文献
172.
T. R. Chen Y. Zhuang Y. J. Xu P. Derry N. Bar-Chaim A. Yariv B. Yu Q. Z. Wang Y. Q. Zhou 《Optics & Laser Technology》1990,22(4)
Experimental studies and theoretical analyses on the effect of dielectric coatings on semiconductor laser performance are presented. It is demonstrated that the dielectric coating technique is a powerful means of controlling the laser threshold current, external quantum efficiency, maximum output power, longitudinal mode behaviour, lasing wavelength and spectral linewidth. 相似文献
173.
Statistical determination of the length dependence of high-order polarization mode dispersion 总被引:4,自引:0,他引:4
We describe a method of characterizing high-order polarization mode dispersion (PMD). Using a new expansion to approximate the Jones matrix of a polarization-dispersive medium, we study the length dependence of high-order PMD to the fourth order. A simple rule for the asymptotic behavior of PMD for short and long fibers is found. It is also shown that, in long fibers (~1000 km), at 40 Gbits/s the third- and fourth-order PMD may become comparable to the second-order PMD. 相似文献
174.
The bacterium E. coli maneuvers itself to regions with high chemoattractant concentrations by performing two stereotypical moves: "runs," in which it moves in near-straight lines, and "tumbles," in which it does not advance but changes direction randomly. The duration of each move is stochastic and depends upon the chemoattractant concentration experienced in the recent past. We relate this stochastic behavior to the steady-state density of a bacterium population, and we derive the latter as a function of chemoattractant concentration. In contrast to earlier treatments, here we account for the effects of temporal correlations and variable tumbling durations. A range of behaviors is obtained that depends subtly upon several aspects of the system -- memory, correlation, and tumbling stochasticity, in particular. 相似文献