Impact of molecular absorption on the design of free space optical communications

Artaud, Géraldine; Benammar, Bouchra; Jouglet, D.; Canuet, Lucien; Lacan, Jérôme

doi:10.1117/12.2535970

Cited by 5 publications

(9 citation statements)

References 4 publications

(3 reference statements)

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“…Developed by CNES, LMD/CNRS, and NOVELTIS, the Automated Atmospheric Absorption Atlas (4A/OP) radiative transmission software is a fast line-by-line method optimized to perform simulations in IR band across different climates and elevation angles [116]. 4A/OP accounts for a wide range of atmospheric conditions, including: the absorbing gas mixing ratios, temperature scattering, polarization, and zenith angle based on the monochromatic transmittances of individual layers of a stratified atmosphere across a number of atmospheric conditions that allows for wide application and flexibility [113,117].…”

Section: A/opmentioning

confidence: 99%

Laser Beam Atmospheric Propagation Modelling for Aerospace LIDAR Applications

et al. 2021

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Atmospheric effects have a significant impact on the performance of airborne and space laser systems. Traditional methods used to predict propagation effects rely heavily on simplified assumptions of the atmospheric properties and of the interactions with the laser systems. These models need to be continually improved to develop high-resolution predictors of laser performance for applications including LIDAR (light detection and ranging), free-space optical communications, remote sensing, etc. The underlying causes of laser beam attenuation in the atmosphere are examined with particular focus on dominant linear effects: absorption, scattering, turbulence, and non-linear thermal effects such as blooming, kinetic cooling, and bleaching. These phenomena are quantitatively analyzed, highlighting the key assumptions made in the empirical modelling. Absorption and scattering, as the dominant causes of attenuation, are generally well applied in models, but the impact of non-linear phenomena is less well captured and applied as it tends to be application specific. Atmospheric radiative transfer codes, such as MODTRAN, ARTS, etc., and the associated spectral databases, such as HITRAN, are the effective implementation of the total propagative effects on the laser systems. These codes are powerful, widely used tools to analyze performance. However, atmospheric radiative transfer codes make several assumptions that reduce accuracy in favor of faster processing. The key atmospheric radiative transfer models are reviewed highlighting the associated methodologies, assumptions, and application. Empirical models are found to offer a robust analysis of atmospheric propagation, which is particularly well-suited for design, development, test and evaluation (DDT&E) purposes. As such, empirical, semi-empirical, and ensemble methodologies are suggested to compliment and augment the existing atmospheric radiative transfer codes. There is scope to evolve the numerical codes and empirical approaches to better suit aerospace applications, where fast analysis is required over a range of slant paths, incidence angles, altitudes, and atmospheric properties, which are not exhaustively captured in current quantitative performance assessment methods.

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Section: A/opmentioning

confidence: 99%

Laser Beam Atmospheric Propagation Modelling for Aerospace LIDAR Applications

et al. 2021

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“…Previous works also focus on some particular perturbations present in the optical channel. The authors study the impact of the molecular absorption on the uncoded BER in function of the signal band, the satellite elevation, and the climate in Artaud et al 9 Receiver algorithms are designed to cope with one type of impairment: a digital phase‐locked loop to fight the laser phase noise, 10 predistortion or equalization to tackle the nonlinear distortion of the MZM, 11 and so forth.…”

Section: Related Work and Assumptionsmentioning

confidence: 99%

“…We assume that an FEC scheme protects the bits transmitted on the optical link. This scheme consists in an error‐correcting code associated with an interleaver 7 in order to cope with the optical channel perturbations due to atmospheric phenomena (turbulence, 8 molecular absorption, 9 etc.). Other impairments affect the signal such as the laser phase noise 10 or the nonlinear distortion of the Mach–Zehnder modulator (MZM) 11 .…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation of a DVB‐S2 system with a digital optical feeder link

Meric¹,

Péricart²

2020

Satell Commun Network

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We investigate the physical layer performance of a DVB-S2 system with a digital optical feeder link. We consider three scenarios depending on how the DVB-S2 modulator functionalities are distributed between the optical gateway and the satellite. Our main objective is to specify the residual bit error rate of the optical channel error correction scheme in order to ensure a quasierror free link to the users. To that end, we provide theoretical models and/or simulations results. In two scenarios, our results show that a residual bit error rate of 10 −4 (assuming equally distributed errors) gives end-to-end physical layer performance compliant with the DVB-S2 standard. This specification is much higher than typical values in practical systems. K E Y W O R D S digital optical feeder link, digital video broadcasting (DVB), performance evaluation 1 | INTRODUCTION Satellite communications systems require to reduce the overall cost per bit in order to remain competitive with terrestrial solutions and to offer affordable high-speed Internet services. Increasing the total capacity is a logical way to reach these objectives. To that end, high and very high throughput satellite (HTS/VHTS) systems are mainly looking for more bandwidth. 1-3 The multibeam concept using narrow beams combined with frequency reuse enables to maximize the available user link bandwidth. In addition, the satellite operation frequencies are moving from the Ku-band to the Ka-band and beyond (Q/V band). However, HTS and VHTS systems face important challenges such as bandwidth scarcity and ground network size. 3 To tackle these issues, an alternative is to replace the radiofrequency (RF) feeder link by an optical link using the 1550-nm wavelength as depicted in Figure 1. 3-5 Optical technologies benefit from large available bandwidths and less interference issues (due to very narrow beams). We investigate the physical layer performance of a DVB-S2 1 system with a digital optical feeder link. An important matter is how the DVB-S2 modulator features 6 are distributed between the optical ground station (OGS) and the satellite as illustrated in Figure 2. This choice has strong consequences on the design and performance of the system. Our work focuses on three scenarios called regenerative, semiregenerative, and (digital) transparent. All the DVB-S2 modulator functionalities are done on-board in the regenerative case. At the opposite, the optical gateway handles everything in the (digital) transparent scheme. In the semiregenerative scenario, the OGS realizes the DVB-S2 forward error correction (FEC) encoding while the satellite manages the remaining features. The bitstream coming out the DVB-S2 modulator 1/2 serves to modulate the optical signal with a digital waveform such as OOK or DPSK. We assume that an FEC scheme protects the bits transmitted on the optical link. This scheme consists in an error-correcting code associated with an interleaver 7 in order to cope with the optical channel perturbations due to atmospheric phenomena (turbulence, 8 molecular ab...

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“…Optical waves are attenuated by Rayleigh scattering, aerosol scattering and absorption, and molecular absorption lines 22 . The latter is a highly frequency‐selective effect—caused mainly by water vapor and carbon dioxide—that can cause severe discrete signal absorption.…”

Section: Introductionmentioning

confidence: 99%

“…21 Optical waves are attenuated by Rayleigh scattering, aerosol scattering and absorption, and molecular absorption lines. 22 The latter is a highly frequency-selective effect-caused mainly by water vapor and carbon dioxide-that can cause severe discrete signal absorption. Aerosol scattering is again separated into low-altitude effects connected mainly with the underlying terrain (up to heights of few km) and by volcanic ash that is long-term agglomerating in altitudes above 10 km.…”

mentioning

confidence: 99%

Atmospheric absorption and scattering impact on optical satellite‐ground links

Giggenbach

Shrestha

2021

Satell Commun Network

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Free-space radio-frequency (RF) communication links for intersatellite or satelliteto-ground communications are getting increasingly constraint by the insufficient spectrum availability and limited data rate of RF technology. With the advent of large satellite mega-constellation networks for global communications coverage, this limitation of classical RF communication becomes even more critical. Therefore, the establishment of point-to-point free-space optical link technology (FSO) in space will become of paramount importance in future systems, where the application will be for data-relays links, or for mega-constellations inter-satellite links, as well as for direct data downlinks, or from deep-space probes to ground. Further advantages of optical FSO-besides spectrum availability-is its increased power efficiency, higher data rates, avoidance of interference, and inherent protection against interception. When, however, these optical communication links have to pass through Earth's atmosphere, attenuation and scattering effects do influence the signal transmission. In this publication, we investigate the effects of atmospheric attenuation, including the effects of molecular absorption as well as aerosol scattering and absorption, for typical wavelength regions used for FSO, dependent on the link geometries. Based on transmission-simulation databases, we show useful spectral ranges and their specific attenuation strength. Free spectral transmission windows dependent on atmospheric quality and elevation angle are identified for reliable and efficient use of the optical transmission technology in space applications.

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Impact of molecular absorption on the design of free space optical communications

Cited by 5 publications

References 4 publications

Laser Beam Atmospheric Propagation Modelling for Aerospace LIDAR Applications

Laser Beam Atmospheric Propagation Modelling for Aerospace LIDAR Applications

Performance evaluation of a DVB‐S2 system with a digital optical feeder link

Atmospheric absorption and scattering impact on optical satellite‐ground links

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