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971.
Formulas for the two-carrier third-order intermodulation distortion in semiconductor lasers have been reported by many authors. The authors refine the formula further and illustrates the difference in results arising from the refinement, for typical laser parameters.<> 相似文献
972.
The saturation of the 2.71 μm laser output has been measured in erbium-doped ZBLAN singlemode fibres with Er3+ concentrations of 1000, 5000 and 10000 ppm mol. Limits of the single-mode-laser output are discussed 相似文献
973.
T. Takeuchi T. Sasaki M. Hayashi K. Hamamoto K. Makita K. Taguchi K. Komatsu 《Photonics Technology Letters, IEEE》1996,8(3):361-363
A transceiver PIC consisting of a DFB-LD, a receiver PD and a Y-shaped branch waveguides is realized by in-plane bandgap energy controlled selective MOVPE. Both active and passive core layers are formed in one step selective growth, and complicated fabrication procedure is no longer required. More than 1 mW fiber coupled power and 7 GHz receiver bandwidth are obtained. The modulation and detection operations at 500 Mb/s are successfully demonstrated. 相似文献
974.
975.
Wood A.C.G. O'Neill A.G. Phillips P.J. Biswas R.G. Whall T.E. Parker E.H.C. 《Electron Devices, IEEE Transactions on》1993,40(1):157-162
Delta-doped MOSFETs have been fabricated in MBE-grown silicon using for the first time boron as the dopant within the delta layer. Current-voltage characteristics have been measured, and secondary ion mass spectrometry (SIMS) is used to confirm the location of the delta layer and the extent of layer broadening by diffusion during processing. Precise threshold voltages of the devices are difficult to determine since the devices (which all operate in depletion mode) take several volts to switch off. Transconductances of the devices have been measured, and it is shown how analysis of these results can yield estimates of the carrier mobility for transport along the delta layers despite the uncertainty in the threshold voltage. A clear transition is observed in the results which is attributed to the formation of a parasitic surface-channel field-effect transistor, providing conclusive evidence that the devices are conducting along a delta channel for part of the measured range of applied gate biases 相似文献
976.
Flowing and static gas-phase samples of HNO3 in O2 and N2 were analyzed by long-path ultraviolet/visible (UV/VIS) spectroscopy to reveal the presence of both NO2 and NO3, the concentrations of which were calculated using differential absorption cross sections. NO2 is produced predominantly by the heterogeneous decomposition of HNO3, whereas NO3 is generated in the gas phase by the thermal decomposition of N2O5, a product of the self-disproportionation of liquid HNO3. © 1993 John Wiley & Sons, Inc. 相似文献
977.
A kinetic investigation on the monoesterification reaction of the maleic anhydride residue (MA) in styrene-maleic anhydride copolymers with aliphatic alcohols was carried out in ethyl benzene solution. By comparison to classic catalysts such as tributylamine (TBA) and pyridine, 4-dimethylaminopyridine (4DMAP) is by far the most effective catalyst for this reaction. While both general base and nucleophilic mechanisms contribute to the reaction catalyzed by TBA or pyridine, a nucleophilic mechanism prevails with 4DMAP. This reaction is reversible, and its chemical equilibrium constant decreases significantly with increasing temperature. Both kinetic and thermodynamic results showed that in the presence of 4DMAP, the forward and reverse reactions are second and first order, respectively. The existence of side reactions, reactivity of two styrene-maleic anhydride copolymers of different MA contents as well as two aliphatic alcohols of different lengths are also addressed. © 1993 John Wiley & Sons, Inc. 相似文献
978.
It is found that, in the spherical coordinate system, the fundamental solution of the Helmholtz equation in a wedge satisfies the Sommerfeld radiation conditions at infinity uniformly in angle coordinates.Deceased.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 9, pp. 1312–1314, September, 1993. 相似文献
979.
Ku T.K. Chen S.H. Yang C.D. She N.J. Wang C.C. Chen C.F. Hsieh I.J. Cheng H.C. 《Electron Device Letters, IEEE》1996,17(5):208-210
Undoped and phosphorus (P)-doped diamond-clad Si field emitter arrays have been successfully fabricated using microwave plasma chemical vapor deposition (MPCVD) technology. The electron emission from the blunt diamond-clad microtips are much higher than those for the pure Si tips with sharp curvature due to a lower work function. Furthermore, the characteristics of emission current against applied voltage for the P-doped diamond-clad tips show superior emission at lower field to the undoped ones. After the examination of Auger electron spectroscopy (AES) and electrical characteristics of as-grown diamond, such a significant enhancement of the electron emission from the P-doped diamond-clad tips is attributed to a higher electron conductivity and defect densities 相似文献
980.
This paper proposes a sensorless speed measurement scheme that improves the performance of transducerless induction machine drives, especially for low-frequency operation. Speed-related harmonics that arise from rotor slotting and eccentricity are analyzed using digital signal processing. These current harmonics exist at any nonzero speed and are independent of time-varying parameters, such as stator winding resistance. A spectral estimation technique combines multiple current harmonics to determine the rotor speed with more accuracy and less sensitivity to noise than analog filtering methods or the fast Fourier transform. An on-line initialization routine determines machine-specific parameters required for slot harmonic calculations. This speed detector, which has been verified at frequencies as low as 1 Hz, can provide robust, parameter-independent information for parameter tuning or as an input to a sensorless flux observer for a field-oriented drive. The performance of the algorithm is demonstrated over a wide range of inverter frequencies and load conditions 相似文献