放大器的相位噪声与噪声系数关系式理论推导

介绍了二端口器件放大器的噪声对相位噪声的影响,并从理论上对相位噪声和噪声系数之间的关系式进行了推导。     

Noise characteristics of nonlinear semiconductor optical amplifiersin the Gaussian limit

This paper addresses noise properties of nonlinear semiconductor optical amplifiers. From a basic point of view, noise properties of nonlinear optical amplifiers are sufficiently different from those of linear amplifiers to warrant detailed modeling which has not been formulated previously. From a practical point of view, nonlinear semiconductor optical amplifiers are important for future all-optical signal-processing applications which may involve the operation of these devices in a saturated regime. Nonlinear amplifiers are also common in systems operating near 1300 nm and in integrated booster amplifiers. Under nonlinear operating conditions, amplifier noise contains a narrow-band contribution that comes about due to the nonlinear coupling of noise and gain. The more conventional broadband spontaneous noise also changes as the inversion factor becomes power-dependent and varies along the amplifier axis. We analyze noise in nonlinear amplifiers in the Gaussian limit (meaning, for fields consisting of large photon numbers) for CW or NRZ modulated signals and separately for short pulses. We consider the case of a single input as well as configurations of multi-input signals interacting via four-wave mixing. Using a specific detection system for the calculations of electronic signal-to-noise ratios, we demonstrate a reduction in the narrow-band electronic noise due to saturation in the single input case. We also demonstrate a vast advantage of using short pulses in four-wave-mixing applications     

The kinetic power theorem for parametric, longitudinal, electron-beam amplifiers

A power theorem is developed for parametric, longitudinal, electron-beam amplifiers which may be considered as a generalization of Chu's well-known kinetic power theorem. The new power theorem is used to explore the limitations on noise performance of parametric electron-beam amplifiers. It is shown that the electron-beam noise does not impose a basic limit on the noise performance of a parametric electron-beam amplifier in the way a basic limit is imposed upon the noise performance of conventional longitudinal electron-beam amplifiers. The new power theorem can be employed for understanding the operation of parametric beam amplifiers in the same way as Chu's kinetic power theorem has been used for interpreting the opoeration of longitudinal beam amplifiers.     

Propagation of signal and noise in concatenated erbium-doped fiberoptical amplifiers

Signal propagation and noise accumulation in lightwave systems using saturated optical amplifiers as repeaters are analyzed. Numerical simulations of amplified spontaneous emission in concatenated erbium-doped fiber amplifiers indicate that a reach beyond 10000 km is possible with a 1.55-μm system in the absence of fiber nonlinearities. Distributed optical amplifiers are shown to have low noise, but require higher pump power than lumped amplifiers. Three operating modes of an amplifier lightwave system are identified and their relative signal power efficiency and noise performance are described     

Measurement and analysis of phase noise generated fromsemiconductor optical amplifiers

The phase noise generated from traveling-wave semiconductor optical amplifiers is measured. It is found that the phase noise is strongly correlated with the intensity noise and has bandwidth of 600 MHz. Phase-noise formulas are derived for semiconductor optical amplifiers to explain such phase-noise characteristics. It is shown that the phase noise is induced by the carrier density fluctuation associated with the intensity noise and the spontaneous carrier recombination. For the coherent heterodyne DPSK system, the phase noise, instead of the intensity noise, is found to be the limiting factor on the number of repeater amplifiers     

An investigation of the noise figure and conversion efficiency of0.98 μm pumped erbium-doped fiber amplifiers under saturatedconditions

The results of an investigation of the noise figure and conversion efficiency or erbium-doped fiber amplifiers for unsaturated, moderately saturated, and heavily saturated operation are reported. Quantum-limited 3 dB noise figures result only for small signal operation of low-gain amplifiers. For high gain, partially saturated amplifiers useful as in-line repeaters, bidirectional pumping results in the best combination of noise performance and conversion efficiency while co-propagation of signal and pump produces the best noise performance     

Noise characteristic of dye-doped polymer optical fiber amplifiers

The noise in polymer optical amplifiers is mainly derived from the amplification of spontaneous emission （ASE）. ha this paper, the noise characteristic of dye-doped polymer optical fiber amplifiers is studied. The propagation equations of ASE power and the rate equations of dye molecular concentration are found based on the energy level transition of dye. The noise characteristic of optical fiber amplifiers is given by solving above equations numerically, and the relationship between noise figure and parameters of optical fiber amplifiers is investigated in detail. The result shows that the noise figure of dye-doped polymer optical fiber amplifiers will not exceed 5 dB.     

Noise figure of saturated 1310-nm polarization insensitive multiple-quantum-well optical amplifiers

The noise figure degradation due to saturation by amplified spontaneous emission of high-gain 1310-nm polarization insensitive multiple-quantum-well optical amplifiers has been investigated systematically by studying amplifiers of different lengths. It is found that the intrinsic noise figure of 4 dB of a device with 20-dB single-pass gain is degraded to about 5 dB for a device having 36-dB single-pass gain. This degradation in noise figure is very modest, compared to results reported earlier for semiconductor optical amplifiers with bulk-gain media, illustrating the benefits of using a quantum-well gain medium in semiconductor optical amplifiers.     

微波固态反馈放大器的性能分析与自动设计

本文采用不定散射矩阵导出了串联、并联、混联和Mason反馈放大器的定散射矩阵显式表达式，提出了一种反馈放大器噪声参数的简化分析法，从而可快速分析微波反馈放大器的传输和噪声性能。在此方法的基础上，以知识库为支持，实现了微波固态反馈放大器的自动设计。     

Noise temperature in distributed amplifiers

The subject of noise generation in certain types of RF amplifiers is treated. The different physical mechanisms by which noise is generated within the amplifier are discussed. Expressions for the "effective source noise temperature" are derived for distributed amplifiers of the maser, parametric, and tunnel type.     

Molecular amplification and generation of microwaves

This paper is a general introduction to the field of amplification and generation of microwaves using molecular rather than electronic processes. The basic physical properties of molecular systems as related to amplification are reviewed. The properties of molecular amplifiers, such as gain, bandwidth, saturation power, and noise figure are discussed and several specific types of amplifiers are described. These include the molecular-beam maser, the “hot-grid cell”, amplifiers excited by radio-frequency pulses and by “adiabatic fast passage”, and amplifiers based on multilevel molecular internal energy systems, including “optically pumped” amplifiers. Molecular amplifiers may add very little noise to the signal to be amplified: noise figures under 1 dB can be obtained. With suitable feedback, such amplifiers become oscillators of extremely high spectral purity. High gains can be achieved using regeneration, but bandwidths are relatively small. These range from the order of tens of kilocycles for amplifiers using a gaseous molecular system, to megacycles, using solids. Molecular amplifiers saturate at low input powers, of the order of microwatts. Variations of the devices discussed may provide a means of generating millimeter and submillimeter waves     

微波低噪声放大器机助噪声分析的一种方法

本文提出了微波网络计算机辅助噪声分析的一种方法,推导了所需的等效噪声参数变换公式,这些公式考虑了所有电路元件引入的噪声源.该法可用来解决具有反馈、有耗匹配微波低噪声放大器的噪声分析问题.文中给出了较为详细的噪声分析程序框图.     

1480-nm pumped erbium-doped fiber amplifiers with optimized noiseperformance for AM-VSB distribution systems

Within analog video transmission systems, optical amplifiers have to display simultaneously good noise and output power performance because of the very stringent carrier-to-noise ratio requirements imposed by the AM-VSB modulation format. We show, theoretically and experimentally, that properly designed forward 1480-nm pumped erbium-doped fiber amplifiers can deliver +16 dBm saturated output power with noise parameter (n_sp/C_x) as low as 3.5dB. These amplifiers do not exhibit significant degradation of their noise performance when the input powers are as large as +3 dBm. These characteristics make 1480-nm pumped amplifiers suitable for AM-VSB transmission systems     

Statistical analysis of coherent ultrashort light pulse CDMA with multiple optical amplifiers using additive noise model

This paper describes a study of the performance of various configurations for placing multiple optical amplifiers in a typical coherent ultrashort light pulse code-division multiple access (CULP-CDMA) communication system using the additive noise model. For this study, a comprehensive performance analysis was developed that takes into account multiple-access noise, noise due to optical amplifiers, and thermal noise using the saddle-point approximation technique. Prior to obtaining the overall system performance, the input/output statistical models for different elements of the system such as encoders/decoders, star coupler, and optical amplifiers were obtained. Performance comparisons between an ideal and lossless quantum-limited case and a typical CULP-CDMA with various losses exhibit more than 30 dB more power requirement to obtain the same bit-error rate (BER). Considering the saturation effect of optical amplifiers, this paper discusses an algorithm for amplifiers' gain setting in various stages of the network in order to overcome the nonlinear effects on signal modulation in optical amplifiers. Finally, using this algorithm, various configurations of multiple optical amplifiers in CULP-CDMA are discussed and the rules for the required optimum number of amplifiers are shown with their corresponding optimum locations to be implemented along the CULP-CDMA system.     

Series-Tuned Amplifier, a Low Noise Preamplifier

Parallel-tuned circuits are commonly used in transistor bandpass amplifiers, e.g., IF amplifiers. However, series-tuned circuits have some important advantages. This correspondence presents a simple noise analysis for a parallel-tuned and a series-tuned amplifier. The transfer functions of both amplifiers are similar, but the series-tuned amplifier gives a smaller noise figure. Hence, series-tuned circuits are especially advantageous in preamplifiers.     

Minimum Noise Figure of Paramps with F2 Frequency Dependent Apparent R/sub s/ (Correspondence)

The effect of inverse-squared frequency dependence of the apparent resistance of varactor diodes is discussed in the optimization of the noise figure of negative resistance and up-converter parametric amplifiers. Optimum idler frequency for a given signal frequency for minimum noise figure is calculated. It is also shown that about twofold improvement in the noise figure is obtained if the proper idler frequency is used for negative resistance amplifiers. It is also shown that the value of the optimum loading changes for upconverter amplifiers.     

Noise figure for erbium-doped optical fibre amplifiers

A rate equation model is used to calculate the excess noise figure for erbium-doped fibre amplifiers. It is shown that erbium amplifiers can operate with high gain and can have noise figures only 0.2 dB above the quantum limit     

Lightwave systems with optical amplifiers

Fiber-optic communication systems using semiconductor laser amplifiers are investigated theoretically and experimentally. The noise and bit-error-rate characteristics of lightwave systems with optical amplifiers are calculated and the dependence of system performance on amplifier characteristics such as optical bandwidth, noise figure, gain, etc., is shown. Experimental results for both a 4-Gb/s optical preamplifier as well as coherent and direct detection systems with four inline amplifiers are presented     

Semiconductor optical amplifiers

Reviews some of the recent advances in semiconductor laser amplifiers and highlights some of the device and system issues connected with the use of optical amplifiers. Particular attention is given to noise properties, system applications (i.e. in-line amplifiers, power amplifiers, and receiver preamplifiers), and nonlinear effects. Finally, semiconductor amplifiers are compared with fiber amplifiers     

Interdependence of Gain and Idler Conversion Loss in Parametric Amplifiers (Letters)

lnterdependence of gain and idler conversion has been experimentally investigated in parametric amplifiers having, single diode circuit configuration. The results indicate that for high gain amplifiers, the inherent idler rejection is inadequate, and larger lengths of pump waveguide, designed to be below cutoff at idler frequency, are to be used for reducing the effect of pump sideband noise on the noise temperature of the parametric amplifiers.