Optical sampling of GHz charge density modulation in silicon bipolar junction transistors

We report the use of optical sampling employing a gain-switched 1.3?m semiconductor laser to observe charge density modulation in a 1.5?m x 5?m emitter silicon BJT. The overall system bandwidth is 8 GHz. The device under test is switched at frequencies from 100 MHz to 2.5 GHz.     

Measurement of a VPE-transported DFB laser with blue-shiftedfrequency modulation response from DC to 2 GHz

The frequency modulation characteristics of a VPE-transported 1.53 μm wavelength GaInAsP-InP DFB semiconductor diode laser was measured. Below approximately 0.7 mW optical output power per facet, it exhibited a smooth, blue-shifted, frequency modulation response from DC to 2 GHz. In the modulation frequency range of 10 MHz to 100 MHz it exhibited a |Δf/ΔI| of 0.5-1.8 GHz/mA, depending on the biasing level     

Features of the dynamics of a josephson junction biased by a sinusoidal microwave current

Applicability of the voltage biasing approximation, which is widely used for estimating the width of Shapiro steps in the I–V characteristics of Josephson junctions biased by a sinusoidal microwave current, is considered in relation to the bias-current frequency f. For the first time, the configuration of the phase-lock area is shown to depend on the frequency parameter μ = (2πf)/ω_c. It is shown that overlapping Shapiro steps, which are typical of tunnel Josephson structures with high V _c and ω_c, exist in the range μ ≤ 1. For μ > 1, Shapiro steps do not overlap, which is typical of overdamped Josephson structures with relatively low V _c. For the practically important case of sinusoidal microwave bias, the diagrams showing the phase-lock areas are plotted for several values of parameter μ. On the basis of these diagrams, the operating principle of ac-voltage quantum standards is illustrated, the methods of their design are specified, and the requirements for the bias current are formulated.     

Carrier lifetime measurement of a junction laser using direct modulation

A carrier lifetime measurement under lasing conditions using microwave techniques is reported. The direct modulation characteristic of a junction laser is analyzed, based on the rate equations, and a resonance-like phenomenon of the modulated output is calculated at a fixed frequency determined by the parameters of the junction diode. This frequency occurs just before the modulation cutoff frequency of the diode. The minority carrier lifetime in the active region of the junction laser is expressed in terms of this frequency and other parameters. A modulation experiment was performed using a microwave frequency modulated bias pulse current. The resonance-like phenomenon was confirmed experimentally and the carrier lifetime was determined from the analysis presented here.     

Noise characteristics of stripe-geometry double-heterostructure junction lasers operating continuously--I. Intensity noise at room temperature

Measurements of the noise fluctuations present in the output intensity from stripe-geometry double-heterostructure junction lasers operating continuously at room temperature are reported. In some but not all the lasers studied, the low-frequency (50-MHz) fluctuations exhibit the quieting expected of an amplitude-stabilized oscillator operating above threshold. The intensity noise in these lasers becomes shot noise limited at currents about 10 percent above threshold, even when many longitudinal modes are oscillating. Additional measurements demonstrate explicitly the effective elimination of the wave-interaction, or excess, noise during the transit of the threshold region. However, in other lasers which are nominally similar, only a partial reduction of the excess noise occurs above threshold, resulting in a noise level which can be more than ten times the shot-noise limit. In addition, we find in all lasers studied thus far no quieting at high frequencies (4 GHz), in apparent contradiction to the behavior expected of a well-stabilized oscillator.     

Optical frequency modulation and intensity modulation suppression in a master-slave semiconductor laser system with direct modulation of the master laser

An injection-locked laser system where the master laser is directly modulated is analyzed using rate equations. Both quasi-static and dynamic analyses are carried out in order to ensure that the parameters lie inside the locking range. The analysis is valid for all injection levels. The quasi-static analysis provides a good basis for explaining the phenomena. It is shown that, for a given detuning frequency, maximum suppression of intensity modulation (IM) occurs at a specific value of the injection ratio. At low frequencies, the frequency modulation (FM) index of the slave laser bears a constant ratio to the FM index of the master laser of less than unity. It is illustrated that the direct FM scheme is only viable for modulation frequencies up to about 100 MHz. Large IM suppression can only be achieved for large values of the linewidth enhancement factor of the slave laser, small magnitude of the detuning frequency, and low injection ratio. The latter two conditions are associated with narrow limits on stable operation, and care should be taken to avoid instability.     

Optical transmission using PSK-modulated subcarriers at frequencies to 16 GHz

The use of a 1.3 ?m InGaAsP constricted mesa laser to transmit microwave subcarriers at frequencies from 3 GHz to 16 GHz is described. The subcarriers are phase-modulated at 2 Gbit/s and the error rate is measured for transmission over 34 km. The effect of laser intensity noise on the system transmission is described.     

调制激光激发PN结少数载流子分布及频域响应特性研究

为建立载流子辐射检测Si基太阳能电池的理论模 型,基于太阳能电池非线性耦合方程对调制激光激 励下Si太阳能电池过剩少数载流子的空间分布与频率响应特性进行了仿真分析,对基区、耗 尽层和发射区 的载流子分布与超带宽调制激光的波长、功率密度和调制频率的关系进行了定量研究,通过 仿真结果选定 调制激光的最佳参数范围,进行了载流子辐射频域响应和载流子寿命对频域响应影响的仿 真计算。仿真 结果表明,过剩载流子浓度随扫描频率的增加呈现非线性特征,所用仿真模型对激发参数和 输运参数有较高 的灵敏度。最后对Si基太阳能电池片进行了扫频验证实验,实验结果与仿真结果符合良好, 表明所使用的 仿真方法能够预测载流子辐射技术的检测结果,可用于对调制载流子辐射检测技术仿真和结 果预测。     

A 100 MHz to 1 GHz Variable Gain Amplifier in a 8 GHz 1.2 µm BiCMOS Process

A variable gain amplifier with linear gain control has been implemented in a commercially available 8 GHz 1.2 µm BiCMOS process. The gain adjustment linearization is based on forcing a linearly controllable current through diode-connected transistors, thus generating an internal logarithmic control voltage for the Gilbert-type variable gain cell. A Cherry-Hopper type gain stage is used to provide most of the available gain. Thus, the maximum differential gain is 10 dB with over 1 GHz bandwidth and –6.9 dBm input –-1 dB compression power. Gain adjustment range of 50 dB at 200 MHz and 38 dB at 960 MHz is reported. The chip area is 1.15 × 2.15 mm and it consumes 40 mA from a 5 V supply.     

2.5 GHz and 5 GHz harmonic mode-locking of a diode-pumped bulkerbium-ytterbium glass laser at 1.5 microns

Third-order harmonic mode locking of a diode-laser pumped bulk Er:Yb:glass laser by frequency modulation with a lithium niobate modulator is reported. Stable pulses at a repetition rate of 2.5 and 5 GHz with a pulse duration down to 9.6 ps are obtained. The average output power is 3 mW, the pulse peak power is 120 mW at 2.5 GHz repetition rate, and the pulses are approximately 1.4 times transform limited. The pulse duration can be increased up to 30 ps by decreasing the mode-locker drive power     

1.2 GHz CMOS全集成锁相环的设计

在分析影响锁相环性能的各种因素的基础上,采用相应的优化方法设计了一款全集成的1．2GHz LC锁相环。详细介绍了该锁相环中各模块电路（包括LC型压控振荡器,预分频器,分频器,鉴频／鉴相器,含有带隙基准电流源的电荷泵以及片上无源滤波器等）的设计,并且给出了仿真结果。该锁相环采用SMIC0．18μm RF CMOS工艺设计实现,其中无源滤波器也集成在片上,实现了完全片上集成。     

Increased modulation bandwidth up to 20 GHz of a detuned-loaded DBRlaser

A small signal amplitude modulation bandwidth of 20 GHz has been obtained with a three-section tunable DBR laser fabricated with semi-insulating current blocking layers grown by hydride VPE. The modulation bandwidth and laser linewidth are strongly dependent on the position of the lasing mode relative to the Bragg reflection peak     

Response of a P-N junction to a linearly decreasing current

A study is made to determine analytically the time variation of the terminal voltage of a p-n junction in response to a terminal current which starts with a large forward value and continues to decrease linearly until the reverse saturation is attained. It is shown that the period between the reversal of current and the reversal of voltage depends exclusively on the lifetime, diffusion length, and thermal equilibrium densities of minority carriers in both regions of the junction. For some cases, the period between the reversal of current and voltage reduces to half the lifetime of either of the two types of minority carriers. This property allows measuring the lifetime of minority carriers for certain p-n junctions by relatively simple means.     

808nm量子阱激光器电流调制特性的实验研究

本文首次对高功率GaAs/GaAIAs量子阱激光器（808nm)的低频（100Hz-20KHz)电流调制特性进行了实验研究。结果表明：激光发射的接通延迟时间、阈值电流、正脉冲的占空比、平均功率、峰值功率随调制频率和电流而变化。     

Efficient modulation and coupling of CW junction laser light using electrooptic waveguides

The use of an electrooptical-waveguide modulator to achieve over 80-percent modulation of 7980-Å light from a room temperature laser diode operating at 10 mW CW is reported. The insertion loss of the modulator including couplers is 8.5 dB, and the output beam has high coherence.     

Self modulation at gigahertz frequencies of a diode laser coupled to an external cavity

An external cavity coupled to a continuously operating GaAs diode laser has been found to cause modulation of the light output at a frequency within the range of 0.6?2.2GHz. The modulation depth is close to 100% and the linewidth is 200kHz.     

Modification of a commercial fir laser system for efficient operation at 337 GHz

An Apollo Lasers model 122 far infrared laser system has been modified to allow sustained efficient operation at a wavelength of 890μm (337 Gigahertz). Modifications included installation of a circular metallic output cavity and redesign of the input and output couplers. Beam output profiles were taken to verify correct operation of the output coupler assembly. A simple automatic controller was implemented to provide unattended, automatic operation of the system.     

Application of a sinusoidal internal model to current control of three-phase utility-interface converters

Three-phase voltage-source converters are used as utility interfaces. In such a case, the converter line currents are required to track sinusoidal references synchronized with the utility grid without a steady-state error. In this paper a current control method based on a sinusoidal internal model is employed. The method uses a sine transfer function with a specified resonant frequency, which is called an S regulator. The combination of a conventional proportional-integral (PI) regulator and an S regulator is called a PIS regulator. The PIS regulator ensures that the steady-state error in response to any step changes in a reference signal at the resonant frequency and 0 Hz reduces to zero. An experiment was carried out using a 1-kVA prototype of three utility-interface converters, a voltage-source rectifier, an active power filter, and static synchronous compensator. Almost perfect current-tracking performance could be observed.