Spectral and mode characteristics of InAsSbP/InAsSb/InAsSbP lasers in the spectral region near 3.3 µm

The characteristic features of the continuous-wave lasing spectra near 3.3 μm of multimode InAsSbP/InAsSb/InAsSbP double-heterostructure diode lasers are shown. The observation of mode switching to longer and shorter wavelengths at cryogenic temperatures is reported. It is shown that suppression of the longitudinal side modes closest to the main mode results in large mode jumps in energy during mode tuning by current. The characteristics which were observed are explained by gain spectrum inhomogeneity due to spectral hole burning in narrow-gap semiconductors. The intraband charge-carrier relaxation times in the active region are estimated. Fiz. Tekh. Poluprovodn. 39, 1139–1144 (September 1998)     

Implementation of media processors

Conventional standard processors do not correspond well to the characteristics of multimedia signal processor algorithms. Therefore, special architectural approaches are necessary for multimedia processors to deliver the required high processing power with efficient use of hardware resources. Programmable approaches offer a high degree of flexibility. In order to attain multimedia signal processor performance, architectural strategies for programmable processors are based on parallelization and adaptation principles. The future multimedia signal processor implementation hinges upon an optimal trade-off between the two design spaces, which can be effectively addressed by a codesign approach     

Noise contribution of the body resistance in partially-depleted SOIMOSFETs

An additional noise component is observed in the noise spectrum of transistors in a partially-depleted (PD) medium-thickness SOI-CMOS technology. We identify the origin of this additional noise in the noisy resistance of the body film. This resistance, coupled to the gate capacitance, forms an RC filter and generates the hump-shape of the additional noise component. Several experimental observations that support this model are presented     

Modeling statistical dopant fluctuations in MOS transistors

The impact of statistical dopant fluctuations on the threshold voltage V_T and device performance of silicon MOSFET's is investigated by means of analytical and numerical modeling. A new analytical model describing dopant fluctuations in the active device area enables the derivation of the standard deviation, σV_T , of the threshold voltage distribution for arbitrary channel doping profiles. Using the MINIMOS device simulator to extend the analytical approach, it is found that σV_T, can be properly derived from two-dimensional (2-D) or three-dimensional (3-D) simulations using a relatively coarse simulation grid. Evaluating the threshold voltage shift arising from dopant fluctuations, on the other hand, calls for full 3-D simulations with a numerical grid that is sufficiently refined to represent the discrete nature of the dopant distribution. The average V_T-shift is found to be positive for long, narrow devices, and negative for short, wide devices. The fast 2-D MINIMOS modeling of dopant fluctuations enables an extensive statistical analysis of the intrinsic spreading in a large set of compact model parameters for state-of-the-art CMOS technology. It is predicted that V_T-variations due to dopant fluctuations become unacceptably large in CMOS generations of 0.18 μm and beyond when the present scaling scenarios are pursued. Parameter variations can be drastically reduced by using alternative device designs with ground-plane channel profiles     

Gyrotron coaxial cylindrical resonators with corrugated innerconductor: Theory and experiment

Gyrotron coaxial resonators with a longitudinally slotted inner cylinder are examined analytically using a surface impedance model, from which expressions for the electromagnetic field, ohmic quality (Q) factor, and characteristic equation of the transverse eigenvalues χ _m,p are obtained. The major attributes of such resonators are expressed by the dependence of χ_m,p on the parameter C-defined as the ratio of the outer to inner radii of the coaxial structure. In that connection, the effect of the corrugation parameters on χ_m,p is particularly investigated on the basis of an expression derived for the slope function dχ_m,p,p/dC. It is shown that the χ_m,p(C) curve may either exhibit oscillatory behavior or present a flat portion over a wide range of C depending on the corrugation parameters chosen. The theory is checked against experiment in which resonant frequencies and total Q factors were measured for TE modes operating in the range of 8-16 GHz in a coaxial cavity with 40 slots. Good agreement is found in that the magnitude of the relative error in frequency is less than 0.5%. Corrugated coaxial resonators prove to be relevant to megawatt gyrotrons where highly selective cavities are required to ensure high conversion efficiency     

Second Quantization of the Stueckelberg Relativistic Quantum Theory and Associated Gauge Fields

The gauge compensation fields induced by the differential operators of the Stueckelberg-Schrödinger equation are discussed, as well as the relation between these fields and the standard Maxwell fields; An action is constructed and the second quantization of the fields carried out using a constraint procedure. The properties of the second quantized matter fields are discussed.     

Linear crosstalk in 4×4 semiconductor optical amplifier gateswitch matrix

We report a comprehensive crosstalk investigation of a packaged InGaAsP/InP 4×4 semiconductor optical amplifier gate switch matrix, experimentally as well as theoretically. For a fully loaded switch with the same wavelength on all four inputs, all possible switching combinations are analyzed, thus yielding realistic crosstalk figures. Coherent and incoherent crosstalk phenomena are identified, and a switch crosstalk less than -40 dB has been measured     

Ultralow-voltage boron-doped diamond field emitter vacuum diode

A boron-doped diamond field emitter diode with ultralow turn-on voltage and high emission current is reported. The diamond field emitter diode structure with a built-in cap was fabricated using molds and electrostatic bonding techniques. The emission current versus anode voltage of the capped diamond emitter diode with boron doping, sp² content, and vacuum thermal electric (VTE) treatment shows a very low turn-on voltage of 2 V. A high emission current of 1 μA at an anode voltage of less than 10 V can be obtained from a single diamond tip. The turn-on voltage is significantly lower than comparable silicon field emitters     

Gordon-Haus timing jitter reduction in dispersion-managed solitoncommunications

An analytic theory is presented which demonstrates that the noise induced Gordon-Haus timing jitter in arbitrary dispersion-managed transmission systems is reduced by the power-enhancement factor required to support a dispersion-managed solitons provided the path-average soliton period is much greater than the dispersion-map period. The analysis further predicts the behaviour of the amplitude, width, and quadratic chirp fluctuations due to the amplified spontaneous emission (ASE) noise