{"title":"A novel ground-based receiver for EDRS","authors":"D. Miklusis, Z. Sodnik","doi":"10.1117/12.2550573","DOIUrl":"https://doi.org/10.1117/12.2550573","url":null,"abstract":"Within the frame of European Data Relay System (EDRS) upgrades, ESA is developing technologies for reliable optical communication links through atmospheric turbulence. This includes adaptive optics for wave-front correction on the downlink (and pre-distortion on the uplink), but a promising alternative to adaptive optics is a self-homodyne multimode differential phase shift interferometer, which doesn’t require phase-integrity of the incoming signal. Moreover, a custom-made avalanche photo detector (APD) with 80μm active area was developed for efficient conversion into an electrical signal. Field test were carried out from ESA’s optical ground station (OGS) with a laser communication terminal (LCT) onboard the Alphasat satellite in geosynchronous orbit.","PeriodicalId":306340,"journal":{"name":"Free-Space Laser Communications XXXII","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121418175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Free-space optical communication for CubeSats in low lunar orbit: LLO","authors":"P. Goorjian","doi":"10.1117/12.2542134","DOIUrl":"https://doi.org/10.1117/12.2542134","url":null,"abstract":"A fine pointing capability has been developed for laser beam pointing to augment body pointing by CubeSats. An application is made to CubeSats in Low Lunar Orbit (LLO), at 100 km. Body pointing was used by Aerospace Corporation for CubeSats in LEO in NASA’s Optical Communications and Sensors Demonstration (OCSD) program. Computer simulations of this fine pointing capability have been applied to the OCSD program. With fine pointing, the spot size on the Earth could be reduced by a factor of eight with a reduction in laser output power by a factor of sixty-four, thereby mitigating the thermal load challenge on the CubeSats. The same reductions in spot size and laser output power can be achieved for CubeSats in LLO. The new method uses laser arrays for fine laser beam pointing and does not use moving parts. It combines a lens system and a VCSEL/Photodetector Array. For these electro-optical systems, reaction times to pointing changes and vibrations are on a nanosecond time scale, much faster than those for mechanical systems. Results from computer simulations will be presented.","PeriodicalId":306340,"journal":{"name":"Free-Space Laser Communications XXXII","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115841840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yousef K. Chahine, S. Tedder, Brian E. Vyhnalek, Adam C. Wroblewski
{"title":"Beam propagation through atmospheric turbulence using an altitude-dependent structure profile with non-uniformly distributed phase screens","authors":"Yousef K. Chahine, S. Tedder, Brian E. Vyhnalek, Adam C. Wroblewski","doi":"10.1117/12.2543583","DOIUrl":"https://doi.org/10.1117/12.2543583","url":null,"abstract":"Modeling the effects of atmospheric turbulence on optical beam propagation is a key element in the design and analysis of free-space optical communication systems. Numerical wave optics simulations provide a particularly useful technique for understanding the degradation of the optical field in the receiver plane when the analytical theory is insufficient for characterizing the atmospheric channel. Motivated by such an application, we use a splitstep method modeling the turbulence along the propagation path as a series of thin random phase screens with modified von Karman refractive index statistics using the Hufnagel-Valley turbulence profile to determine the effective structure constant for each screen. In this work, we employ a space-to-ground case study to examine the irradiance and phase statistics for both uniformly and non-uniformly spaced screens along the propagation path and compare to analytical results. We find that better agreement with the analytical theory is obtained using a non-uniform spacing with the effective structure constant for each screen chosen to minimize its contribution to the scintillation in the receiver plane. We evaluate this method as a flexible alternative to other standard layered models used in astronomical imaging applications.","PeriodicalId":306340,"journal":{"name":"Free-Space Laser Communications XXXII","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124203478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Tedder, Bertram Floyd, Yousef K. Chahine, B. Croop, Brian E. Vyhnalek, C. Betters, S. Leon-Saval
{"title":"Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application","authors":"S. Tedder, Bertram Floyd, Yousef K. Chahine, B. Croop, Brian E. Vyhnalek, C. Betters, S. Leon-Saval","doi":"10.1117/12.2542848","DOIUrl":"https://doi.org/10.1117/12.2542848","url":null,"abstract":"Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few-mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r0=8.6. Furthermore, the coupling loss of the few-mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array.","PeriodicalId":306340,"journal":{"name":"Free-Space Laser Communications XXXII","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126454261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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