Experimental observations of channel reciprocity in single-mode free-space optical links

Parenti, Ronald R.; Roth, Jeffrey M.; Shapiro, Jeffrey H.; Walther, Frederick G.; Greco, Joseph A.

doi:10.1364/oe.20.021635

Cited by 42 publications

(15 citation statements)

References 12 publications

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“…A more effective solution to this challenge is provided by the reciprocity of a single-mode link through the atmosphere. The atmosphere has been shown both theoretically [48][49][50][51] and through measurements of amplitude fluctuations [51,52] to be reciprocal for propagation times shorter than the coherence time of the turbulence. In Ref.…”

Section: Implications For Stability and Accuracy Of One-way Opticamentioning

confidence: 99%

Optical phase noise from atmospheric fluctuations and its impact on optical time-frequency transfer

et al. 2014

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The time of flight for a laser beam through the atmosphere will fluctuate as the path-averaged index of refraction varies with atmospheric turbulence, air temperature, and pressure. We measure these fluctuations by transmitting optical pulses from a frequency comb across a 2-km horizontal path and detecting variations in their time of flight through linear optical sampling. This technique is capable of continuous measurements, with femtosecond resolution, over time scales of many hours despite turbulence-induced signal fading. The power spectral density for the time of flight, or equivalently for the optical phase, follows a simple power-law response of ∝f −2.3 measured down to Fourier frequencies, f , of 100 μHz. There is no evidence of a roll-off at low frequencies associated with an outer scale for turbulence. Both of these results depart from the predictions of turbulence theory, but are consistent with some other results in the literature. We discuss the implications for the stability and accuracy of one-way optical time-frequency transfer.

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Section: Implications For Stability and Accuracy Of One-way Opticamentioning

confidence: 99%

Optical phase noise from atmospheric fluctuations and its impact on optical time-frequency transfer

et al. 2014

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“…Theoretical studies performed in the 70s showed that atmospheric turbulence has a reciprocal nature [267], [268], meaning that two laser beams propagating in opposite directions experience the same atmospheric turbulence distortions. Atmospheric turbulence reciprocity was later confirmed experimentally [269], [270]. Through reciprocity, a pilot signal from a receiver can be used at a transmitter to provide channel state information (CSI), and based on this, various strategies may be adopted at the transmission terminal, including adaptive modulation, varying bit rate, and beam phase and amplitude pre-compensation [267].…”

Section: B Atmospheric Turbulence Effects Mitigationmentioning

confidence: 94%

Communicating Using Spatial Mode Multiplexing: Potentials, Challenges, and Perspectives

Trichili

Park

Zghal

et al. 2019

IEEE Commun. Surv. Tutorials

191

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Time, polarization, and wavelength multiplexing schemes have been used to satisfy the growing need of transmission capacity. Using space as a new dimension for communication systems has been recently suggested as a versatile technique to address future bandwidth issues. We review the potentials of harnessing the space as an additional degree of freedom for communication applications including free space optics, optical fiber installation, underwater wireless optical links, on-chip interconnects, data center indoor connections, radio frequency and acoustic communications. We focus on the orbital angular momentum (OAM) modes and equally identify the challenges related to each of the applications of spatial modes and the particular OAM modes in communication. We further discuss the perspectives of this emerging technology. Finally, we provide the open research directions and we discuss the practical deployment of OAM communication links for different applications. ). 4 in the future. We also summarize the open problems and the future research directions. A discussion of the practicability and cost of multi-OAM communication is also included. II. OAM POTENTIALS A. Free Space Optical CommunicationFSO is a license free wireless communication configuration that has recently received much interest for a variety of applications. FSO is an attractive solution for last mile connectivity problems, particularly for communication networks, when the installation of fiber optics is costly or not possible [66]. FSO can be also used to establish inter-building secure communication, and can be deployed as a backup to optical fibers. Wireless optical communication can guarantee a line-of-sight (LoS) high bit rate wireless transmission over long distances, up to several kilometers. Furthermore, FSO communication is considered as a promising technique to scale down bandwidth challenges in future 5G networks [67].Multiple wavelength FSO provides better transmission, as demonstrated in [68], [69]. Data can be mapped on advanced modulation formats to achieve high bit rates and high spectral efficiency levels [70]- [72]. Another option is multiple-input and multiple-output (MIMO) FSO communication in which multiple lasers are positioned to transmit Gaussian beams to multiple receiving apertures [73]. Over the last few years, it has been proven that it is possible to transmit information over spatially structured light beams [21], [74], [75] including OAM beams and plane waves. Our focus is on the OAM modes of light.The first PoC communication experiment incorporating OAMs in free space was carried out in 2004 by Gibson and co-workers [21]. Over a 15-meter long link, 8 -spaced values were chosen along the Gaussian beam as an alphabet for the communication. OAM beams were generated and detected using two light modulators. Since then, much progress has been made and free space transmission capacity of over 1 Tbit/s is, today, possible [76]- [78]. By performing three dimensional multiplexing, Huang and co-workers were able to attain a 100 Tbi...

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“…Theoretical studies in the '70s revealed that atmospheric turbulence has a reciprocal nature [18], [19], meaning that two laser beams propagating in opposite directions experience the same atmospheric turbulence distortions. Atmospheric turbulence reciprocity has been later confirmed experimentally [20], [21]. Through reciprocity in FSO, a pilot signal from a receiver can be used at the transmitter end to provide channel state information (CSI), based on which the transmitter end could employ various digital signal processing (DSP) techniques.…”

Section: Introductionmentioning

confidence: 93%

On the Reciprocity of Underwater Turbulent Channels

et al. 2019

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Through a series of experiments incorporating two counter-propagating communication channels, we investigate the reciprocity nature of underwater turbulence. Bit error rate measurement and statistical data analysis reveal a high reciprocal nature of turbulence induced by the presence of bubbles, temperature, and salinity. We further demonstrate the effect of distortions at the beam level that could potentially be used for underwater communication system design considerations.

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Experimental observations of channel reciprocity in single-mode free-space optical links

Cited by 42 publications

References 12 publications

Optical phase noise from atmospheric fluctuations and its impact on optical time-frequency transfer

Optical phase noise from atmospheric fluctuations and its impact on optical time-frequency transfer

Communicating Using Spatial Mode Multiplexing: Potentials, Challenges, and Perspectives

On the Reciprocity of Underwater Turbulent Channels

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