Spectral, phase noise and phase modulation characteristics of AM sideband injection-locked semiconductor lasers

AM sideband injection locking is demonstrated experimentally using 1.3?m DFB lasers. The slave laser is injection-locked to a 3 GHz AM sideband of the master laser. By controlling the injection power, a very stable injection-locked state of the slave laser can be achieved. The phase noise and phase modulation characteristics are also discussed.     

A 1.8-GHz injection-locked quadrature CMOS VCO with low phase noise and high phase accuracy

Injection-locked quadrature voltage-controlled oscillators are introduced in this paper as high accuracy, low phase noise, and low-power I and Q generators. A master voltage-controlled oscillator (VCO), running at twice the output frequency, locks two coupled VCOs. The former determines phase noise while the latter sets phase accuracy, thus, breaking the tradeoff between the two parameters, the main limit of free running coupled VCOs, recently proposed in the framework of highly integrated solutions. The proposed design has been tailored to DCS 1800 and prototypes have been fabricated in a 0.18-/spl mu/m CMOS technology. Experiments show a phase noise of -127 dBc/Hz and -139 dBc/Hz at 600 kHz and 3 MHz, respectively, while consuming 10 mA from 1.8 V supply. A 185-dB state-of-the-art phase noise figure of merit results. Accuracy between output signals is determined by means of image band rejection (IBR) measurements on a purposely developed single-side-band upconversion mixer. Minimum IBR among 20 samples is as large as 46 dB.     

On the noise properties of injection-locked oscillators

This paper presents a detailed study of noise properties of injection-locked oscillators. We describe an elaborate numerical model, which offers the accuracy of the best known analytical models when analyzing a single oscillator. Those analytical models do not use perturbation theory since the Wiener nature of the noise renders small-signal analysis inadequate. Our model can be extended to any locked oscillators configuration while keeping the same accuracy. This was not done to date with any of the rigorous analytical models. We analyze unidirectionally and bidirectionally coupled oscillators operating in fundamental or harmonic-locking modes. Harmonic locking is analyzed in detail and the indirect locking process underlying it is identified while the noise of all harmonics is explored in detail. The results of the model are confirmed in a series of experiments employing electrooptic implementations with a photo-HBT-based oscillator. The various configurations we analyze and demonstrate experimentally represent important applications such as spectral purity enhancement, timing extraction, and low-jitter optical pulse generation.     

光纤损耗对双环注入锁定光电振荡器相噪的影响

考虑到光纤的延时损耗,对双环注入锁定光 电振荡器(OEO)建立了理论解析模型;基于建立的模型,研究了光纤损耗对 对其相位噪声的影响。通过实验验证了所建模型的正确性,并得出:如考虑光纤的损耗, 振荡信号的相噪并非随着光纤长度 的增加而降低,当光纤长度增加到一定程度时,光纤的损耗会影响到振荡信号的相噪,使得 光电混合谐振腔的品质因子(Q)降低, 最终相噪会随之呈现增加的趋势。本文研究成果能够在工程中得到广泛应用,可为获取 最佳长度光纤延时线提供参考。     

A low-phase noise injection-locked quadrature voltage-controlled oscillator

This article presents a low-phase noise quadrature voltage-controlled oscillator (QVCO) in which the re-filtering technique of the side-band noise is adopted. In the proposed QVCO, besides using re-filtering technique, the passive elements replaced the noisy and lossy active coupling devices. Therefore, due to the elimination of the associate noise sources of the active coupling devices and re-filtering of side-band noise of the circuit, the proposed QVCO shows an excellent phase-noise and FOM. The proposed QVCO was implemented and simulated in TSMC 0.18 μm RF-CMOS technology. The phase noise of the proposed QVCO at 3 MHz offset frequency from the 3 GHz center frequency is ?144 dBc/Hz, for a current consumption of 11.5 mA at a power supply of 1.8-V. Simulation results show the proposed QVCO can operate with power supply as low as 0.6 V. Monte–Carlo analyses for, 3% device mismatch and process variation, result in phase error lower than 0.8°. Generalizing the proposed coupling technique to several core VCOs very low-phase noise multiphase signals can be generated.     

Phase noise in externally injection-locked oscillator arrays

Previous investigations of noise in mutually synchronized coupled-oscillator systems are extended to include the effects of phase noise introduced by externally injected signals. The analysis is developed for arbitrarily coupled arrays and an arbitrary collection of coherent injected signals, and is illustrated with the specific case of linear chains of nearest neighbor coupled oscillators either globally locked (locking signal applied to each array element) or with the locking signal applied to a single-array element. It is shown that the general behavior is qualitatively similar to a single injection-locked oscillator, with the output noise tracking the injected noise near the carrier, and returning to the free-running array noise far from the carrier, with intermediate behavior significantly influenced by the number of array elements and injection strength. The theory is validated using a five-element GaAs MESFET oscillator array operating at S-band     

Optical phase control of an optically injection-locked FETmicrowave oscillator

A simple technique is proposed and demonstrated for controlling the phase of an optically-injection-locked 7.2-GHz FET oscillator. The relative phase φ between the oscillator and the locking signal is adjusted by optically tuning the oscillator frequency. Locking characteristics described include locking bandwidth (2.6 MHz), phase tuning range (187°), phase modulation (β=0.69 at 500 kHz), and optical tuning (125 MHz)     

FM noise suppression and linewidth reduction in an injection-locked semiconductor laser

An expression is derived for the FM noise spectrum of an injection-locked semiconductor laser. For increasing injection level the FM noise spectrum and the lineshape change gradually from those of the slave laser to those of the master laser. The ultimate linewidth reduction is obtained if the locking bandwidth is large enough to accommodate the frequency fluctuations and if the detuning is controlled carefully.     

Optically induced modulation in FM sideband injection-locked laser diodes

The spectrum of a slave laser in which two different wave-lengths are injected is investigated. A simple rate equation analysis is in reasonable agreement with the experiment and accounts for the asymmetrical response of the induced FM.     

Frequency and intensity noise in injection-locked semiconductor lasers: Theory and experiments

Analytical expressions for the power spectral densities of intensity and frequency noise of single-mode semiconductor lasers operating in a regime of injection locking are derived by appropriately taking into account the spontaneous emission processes into the lasing modes of both the master and slave lasers. They show how the noise spectra of the slave are influenced by the value of the injected power, by the difference between the emission frequencies of the master and slave optical cavities, and how they are correlated to the noise properties of both the master and the free-running slave. In particular, the very low frequency part of the frequency noise of the slave turns out to coincide with that of the master within a certain frequency region whose range increases as the values of the injected signal does, too. We also present measurements of the power spectral densities obtained by means of an experimental apparatus similar to that described in [1] and show how the experimental results are accounted for by the present theory.     

F.m. noise in an injection-locked oscillator when reverse locking exists

A suppression factor for f.m. noise in an injection-locked oscillator is derived under the assumption that the locking source is influenced by some reverse locking. The electrical length between the oscillators is found to have a considerable effect on the noise.     

Mode beating noise reduction of mutually injection-locked erbium-doped fiber laser and laser diode link

We report a mutually injection-locked erbium-doped fiber amplifier (or laser) and Fabry-Pe/spl acute/rot laser diode link (EDFA-FPLD or EDFL-FPLD) for single longitudinal mode lasing with linewidth of 0.012 nm and sidemode suppression ratio of 42 dB. The 3-dB linewidths of <20 MHz and 350 kHz for the EDFL-FPLD and EDFA-FPLD links, respectively, are reported using interferometric determination. The mode-beating noise can be completely eliminated in the EDFA-FPLD link.     

Noise power spectra of optical two-beam interferometers induced by the laser phase noise

Dynamic range of many optical signal processing and sensing devices incorporating two-beam interferometers (such as Mach-Zehnder and Michelson interferometers) can be limited by random phase fluctuations of the optical source emission field. This paper is concerned with the intensity fluctuations, originating from the laser source phase noise, at the output of a two-beam interferometer. Closed-form theoretical expressions are presented for the autocovariance function, variance, and noise power spectral density of the instantaneous output intensity which are valid for any optical biasing phase and any source coherence time. Application of the results in the noise performance evaluation of optical devices incorporating two-beam interferometers will also be shown.     

Spectral broadening due to fibre amplifier phase noise

The authors report, for the first time, measurements of signal spectral broadening caused by phase noise in an erbium-doped fibre amplifier. The spectral broadening was found to be less than 20 kHz. Thus it will not limit the performance of phase or frequency modulated coherent systems employing fibre amplifiers.<>     

Electronic compensation technique to mitigate nonlinear phase noise

Nonlinear phase noise, often called the Gordon-Mollenauer effect, can be compensated electronically by subtracting from the received phase a correction proportional to the received intensity. The optimal scaling factor is derived analytically and found to be approximately equal to half of the ratio of mean nonlinear phase noise and the mean received intensity. Using optimal compensation, the standard deviation of residual phase noise is halved, doubling the transmission distance in systems limited by nonlinear phase noise.     

电子战接收机对本振相位噪声的需求研究

复杂而密集的电子信号对电子战接收机的性能提出了越来越高的要求,本振的相位噪声是电子战接收机的重要指标之一,对接收机的动态范围和数字误码率有着重要影响,针对实际工程中对相位噪声需求难以评估的问题,初步分析了相位噪声对接收机动态范围和数字误码率的影响,并通过实例进行了计算分析,可供工程技术人员参考。     

全相位滤波白噪声产生有色噪声及其功率谱估计

本文提出用全相位数字滤波器这种新型滤波器滤波白噪声产生有色噪声的方法,这种方法比用传统FIR滤波器产生的有色噪声频谱泄漏少,阻带衰减功率大等优点.并且分别用Welch法和全相位法对在有色噪声中混入的双频小信号余弦波进行谱估计,实验证明全相位谱估计性能优于经典谱估计.     

一种新型的相位噪声测试仪

用于无线传输的收发模块的性能主要决定于所用本振的相位噪声。因此模块特性的准确测量，特别是相位噪声的测量，是进行有效通信和广播的基本保证，在雷达系统等特殊的高科技领域应用中也是如此。在普通的相位噪声测量应用中，一台频谱分析仪通常可以满足测试要求。但是，如果需要更大的动态范围、更高的测量精度以及更多的灵活性时，基于锁相环（PLL）的测量方法测量相位噪声更加适合。R＆S（罗德与施瓦茨公司）的信号源分析仪FSUP便在一台仪表上集合了这两种功能：它既提供给用户一台频率可高达50GHz的顶级频谱分析仪（R＆SFSUP），同时具备了基于锁相环测量方法的相位噪声测量功能。     

A retro-directive antenna array with phase conjugation circuit using subharmonically injection-locked self-oscillating mixers

In this paper, a novel phase conjugation circuit and its application to retro-directive antennas are presented. The phase conjugation circuit uses a balanced circuit structure with subharmonically injection locked self-oscillating mixers oscillating at /spl omega/. In the operation, an input signal at /spl omega//2 is converted to its conjugated signal with no external source required for LO signal pumping, and the output signal frequency is locked at the same frequency of the input signal. The developed phase conjugation circuit is implemented with active antennas to become a retro-directive antenna array. Both the theoretical and measured results of phase conjugation and retro-directive performance are shown in good agreement.