Two-dimensional modelling of optical propagation in turbulent atmosphere

Jenu, Markku; Bebbington, D.H.O.

doi:10.1049/el:19930515

Cited by 3 publications

(1 citation statement)

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“…Understanding wave attenuation, scattering, and phase fluctuations introduced by these random media is important for, e.g., remote sensing system design [3] and characterization of communication links [4]. In particular, predictions of radar return from objects obscured by foliage [5] or buried under snow or grass [6] are clearly dependent on knowledge of the effects of such geophysical media on the scattering response.…”

Section: Introductionmentioning

confidence: 99%

Finite-difference time-domain simulation of scattering from objects in continuous random media

Moss

Teixeira

Yang

et al. 2002

IEEE Trans. Geosci. Remote Sensing

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Abstract-A three-dimensional (3-D) finite-difference time-domain (FDTD) scheme is introduced to model the scattering from objects in continuous random media. FDTD techniques have been previously applied to scattering from random rough surfaces and randomly placed objects in a homogeneous background, but little has been done to simulate continuous random media with embedded objects where volumetric scattering effects are important. In this work, Monte Carlo analysis is used in conjunction with FDTD to study the scattering from perfectly electrically conducting (PEC) objects embedded in continuous random media. The random medium models under consideration are chosen to be inhomogeneous soils with a spatially fluctuating random permittivities and prescribed correlation functions. The ability of frequency averaging techniques to discriminate objects in this scenarion is also briefly investigated. The simulation scheme described in this work can be adapted and used to help in interpreting the scattered field data from targets in random environments such as geophysical media, biological media, or atmospheric turbulence.Index Terms-Buried random objects, FDTD methods, Monte Carlo methods, random media.

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Section: Introductionmentioning

confidence: 99%

Finite-difference time-domain simulation of scattering from objects in continuous random media

Moss

Teixeira

Yang

et al. 2002

IEEE Trans. Geosci. Remote Sensing

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Detection of targets in continuous random media: A numerical study using the angular correlation function

Moss

Teixeira

Kong

2002

Micro & Optical Tech Letters

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ever, when the lasing signal powers are higher than 2.5 dBm, the gain saturation at L band takes place, and hence the gain is reduced. This behavior is attributed to the low saturation power at L band. In order to obtain the high gain for a given EDF length, the optimal attenuation in the ring cavity is required to achieve the optimum lasing power. CONCLUSIONImprovement of L-band signal gain by employing the lasing wavelengths as the secondary pump source for the EDF has been demonstrated. A spontaneous emission spectrum up to a wavelength of 1635 nm is observed. The experimental results show that the gain depends on the absorption coefficient of the C band. This indicates the efficiency of the energy transfer between these two bands. The lasing signal powers and the lasing wavelengths also influence the L-band gain. This is ascribed to the interplay between the absorption and amplification of EDF. The experiments imply that the suggested EDFA configuration is applicable to any pump wavelength, because deploying 1480-nm pump laser diodes can provide better power conversion efficiency and generate stronger C-band lasing. Therefore, it is believed that this approach will play an important role in the development of L-band EDFAs for practical DWDM communication systems.

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Phase Noise Analysis of Clock Recovery Based on an Optoelectronic Phase-Locked Loop

Zibar

Mørk

Oxenløwe

et al. 2007

J. Lightwave Technol.

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Abstract-A detailed theoretical analysis of a clock-recovery (CR) scheme based on an optoelectronic phase-locked loop is presented. The analysis emphasizes the phase noise performance, taking into account the noise of the input data signal, the local voltage-controlled oscillator (VCO), and the laser employed in the loop. The effects of loop time delay and the laser transfer function are included in the stochastic differential equations describing the system, and a detailed timing jitter analysis of this type of optoelectronic CR for high-speed optical-time-division-multiplexing systems is performed. It is shown that a large loop length results in a higher timing jitter of the recovered clock signal. The impact of the loop length on the clock signal jitter can be reduced by using a low-noise VCO and a low loop filter bandwidth. Using the model, the timing jitter of the recovered optical and electrical clock signal can be evaluated. We numerically investigate the timing jitter requirements for combined electrical/optical local oscillators, in order for the recovered clock signal to have less jitter than that of the input signal. The timing jitter requirements for the free-running laser and the VCO are more relaxed for the extracted optical clock (lasers's output) signal.Index Terms-Clock recovery (CR), optical time division multiplexing (OTDM), optoelectronic phase-locked loop (OPLL), oscillator noise, phase noise, stochastic differential equations, time delay, timing jitter.

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Two-dimensional modelling of optical propagation in turbulent atmosphere

Cited by 3 publications

References 1 publication

Finite-difference time-domain simulation of scattering from objects in continuous random media

Finite-difference time-domain simulation of scattering from objects in continuous random media

Detection of targets in continuous random media: A numerical study using the angular correlation function

Phase Noise Analysis of Clock Recovery Based on an Optoelectronic Phase-Locked Loop

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