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At least 19 records

The Application of Photonic Lanterns in Free Space Optical Communications

Photonic lanterns offer an efficient solution to transition distorted light from free space into small aperture or single-mode waveguide devices. As a result, photonic lanterns can be useful for free space optical communications, where light is transmitted across a channel with varying atmospheric conditions. This paper will give an overview of studies using photonic lanterns in photon counting optical communication receivers where the detectors are small in aperture and fiber coupled. This paper will also survey other potential uses of photonic lanterns in coherent optical communication receivers or as wavefront sensors in adaptive optical systems.

Optical communicatons↗

The Application of Photonic Lanterns in Free Space Optical Communications

Photonic lanterns offer an efficient solution to transition distorted light from free space into small aperture or single-mode waveguide devices. As a result, photonic lanterns can be useful for free space optical communications, where light is transmitted across a channel with varying atmospheric conditions. This paper will give an overview of studies using photonic lanterns in photon counting optical communication receivers where the detectors are small in aperture and fiber coupled. This paper will also survey other potential uses of photonic lanterns in coherent optical communication receivers or as wavefront sensors in adaptive optical systems.

Optical communications↗

Single-mode Fiber and Few-Mode Fiber Photonic Lanterns Performance Evaluated for Use in a Scalable Real-Time Photon Counting Ground Receiver

Photonic lanterns provide an efficient way of coupling light from a single large-core fiber to multiple small-core fibers. This capability is of interest for space to ground communication applications. In these applications, the optical ground receivers require high-efficiency coupling from an atmospherically distorted focus spot to multiple fiber coupled single pixel super-conducting nanowire detectors. This paper will explore the use of photonic lanterns in a real-time ground receiver that is scalable and constructed with commercial parts. The number of small-core fibers that make a photonic lantern determines the number of spatial modes that they couple. For instance, lanterns made with n number of single-mode fibers can couple n number of spatial modes. Although the laser transmitted from a spacecraft originates as a Gaussian shape, the atmosphere distorts the beam profile by scattering energy into higher-order spatial modes. Therefore, if a ground receiver is sized for a target data rate with n number of detectors, the corresponding lantern made with single-mode fibers will couple n number of spatial modes. The energy of the transmitted beam scattered into spatial modes higher than n will be lost. This paper shows this loss may be reduced by making lanterns with few-mode fibers instead of single-mode fibers, increasing the number of spatial modes that can be coupled and therefore increasing the coupling efficiency to single pixel, single photon detectors. The free space to fiber coupling efficiency of these two types of photonic lanterns are compared over a range of the free-space coupling numerical apertures and mode field diameters. Results indicate the few mode fiber lantern has higher coupling efficiency for telescopes with longer focal lengths under higher turbulent conditions. Also presented is analysis of the jitter added to the system by the lanterns, showing the few-mode fiber photonic lantern adds more jitter than the single-mode fiber lantern, but less than a multimode fiber.

photon counting↗

Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application

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/r(sub 0)=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.

Tedder, Sarah A.↗

Measurements of Few-Mode Fiber Photonic Lanterns in Emulated Atmospheric Conditions for a Low Earth Orbit Space to Ground Optical Communication Receiver Application

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.

Tedder, Sarah A.↗

Photonic Lanterns Applied to Deep Space Optical Communication Receivers

This presentation will begin with an introduction to the design aspects of photon counting optical communications light coupling to detectors. The discussion will continue an introduction to the trade space of light coupling and detector architectures; including solutions that use a photonic lantern. The explored features of the alternative designs will be presented as well as a discussion of remaining aspects that need to be explored.

fiber↗

Multi-Gbps Fiber-Optic Wavefront Sensing Coherent Optical Receiver

We report recent progress on technology developments at the NASA Glenn Research Center using photonic lanterns for coherent optical communications applications. In particular, the development of a spatial mode-diversity optical receiver using a photonic lantern combined with a photonic integrated circuit (PIC). The PIC is designed for compatibility with the NASA Laser Communication Relay Demonstration’s (LCRD) differential phase-shift keying signaling format. We report on the PIC design and future characterization and packaging efforts. Additionally, we report on the development of a 19-channel photonic lantern and provide updates on efforts to use the photonic lantern as a wavefront sensing device. The photonic lantern insertion loss, and spatial-mode transfer characteristics are detailed, as well as the development of a predictive framework in which the intensities in the 19 single-mode output channels are used to reconstruct the wavefront of the light entering the multi-moded input side of the lantern. Finally, we discuss concepts for potential future systems using photonic lanterns and PICs that combine both wavefront sensing and coherent communications onto a single integrated platform.

Optical Communications↗

Real Time Photon-Counting Receiver for High Photon Efficiency Optical Communications

We present a scalable design for a photon-counting ground receiver based on superconducting nanowire single photon detectors (SNSPDs) and field programmable gate array (FPGA) real-time processing for applications to space-to-ground photon starved links, such as the Orion EM-2 Optical Communication Demonstration (O2O), and future deep space or low transmitter power missions. The receiver is designed to receive a serially concatenated pulse position modulation (SCPPM) waveform, which follows the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book standard. The receiver design uses multiple individually fiber coupled, 80% detection efficiency commercial SNSPDs in parallel to scale to a required data rate, and is capable of achieving data rates up to 528 Mbps. For efficient fiber coupling from the telescope to the array of parallel detectors that can be scaled both to telescope aperture size and the number of detectors, we use either a single mode fiber (SMF) photonic lantern or a few-mode fiber (FMF) photonic lantern. In this paper we give an overview of the receiver system design, the characteristics of the photonic lanterns, the performance of the SNSPDs, and system level tests. We show that 40 Mbps can be received using a single SNSPD, and discuss aspects for scaling to higher data rates.

Vyhnalek, Brian E.↗

Real Time Photon-Counting Receiver for High Photon Efficiency Optical Communications

We present a scalable design for a photon-counting ground receiver based on superconducting nanowire single photon detectors (SNSPDs) and field programmable gate array (FPGA) real-time processing for applications to space-to-ground photon starved links, such as the Orion EM-2 Optical Communication Demonstration (O2O), and future deep space or low transmitter power missions. The receiver is designed to receive a serially concatenated pulse position modulation (SCPPM) waveform, which follows the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book standard. The receiver design uses multiple individually fiber coupled, 80% detection efficiency commercial SNSPDs in parallel to scale to a required data rate, and is capable of achieving data rates up to 528 Mbps. For efficient fiber coupling from the telescope to the array of parallel detectors that can be scaled both to telescope aperture size and the number of detectors, we use either a single mode fiber (SMF) photonic lantern or a few-mode fiber (FMF) photonic lantern. In this paper we give an overview of the receiver system design, the characteristics of the photonic lanterns, the performance of the SNSPDs, and system level tests. We show that 40 Mbps can be received using a single SNSPD, and discuss aspects for scaling to higher data rates.

Vyhnalek, Brian E.↗

Performance of A Real-Time Photon Counting Optical Receiver in the Presence of Emulated Channel Fading

Free-space optical communication links with terrestrial ground stations experience fading due to atmospheric scintillation and beam pointing. Fiber-coupled receiver systems experience additional fading at the interface between the fiber and free-space optics of the telescope. The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has characterized a real-time photon-counting optical ground receiver system with an atmospheric fade emulation system. The receiver system is comprised of a fiber interconnect, an array of superconducting nanowire single photon detectors (SNSPDs), and a field programmable gate array (FPGA) based receive modem. Two fiber interconnect/detector architectures have been studied. One architecture uses a 70-mode photonic lantern coupled to seven single pixel SNSPDs. The other architecture uses a 10-mode few-mode fiber (FMF) coupled to a 15-pixel SNSPD array. The receiver system complies with the Consultative Committee for Space Data Systems (CCSDS) Optical Communications High Photon Efficiency Coding and Synchronization Standard, which uses serially concatenated convolutionally coded pulse-position modulation (SCPPM). The CCSDS standard is designed for use in low photon flux missions, including the Orion Artemis-II Optical (O2O) communications demonstration. The standard utilizes a convolutional symbol interleaver which can be resized to mitigate different fades. The fade emulation system employed in this work emulates scintillation-induced, pointing-induced, and coupling-induced fading. This paper gives an overview of the real-time optical receiver system and the fade emulation system. It presents tests results which show the impact of fading on the performance on the receiver. The test results show that in the presence of channel fading, the 70-mode photonic lantern outperforms the 10-mode FMF under higher (D/r_0=9) turbulence conditions due to high fiber-coupling-induced fading and fiber coupling loss on the 10-mode FMF. When operating in lower turbulence (D/r_0=4), the 10-mode FMF outperforms the 70-mode photonic lantern. The paper also shows a larger convolutional interleaver improves the system performance as long as the receiver does not lose acquisition.

optical communications↗

Performance of a real-time photon counting optical receiver in the presence of emulated channel fading

Free-space optical communication links with terrestrial ground stations experience fading due to atmospheric scintillation and beam pointing. Fiber-coupled receiver systems experience additional fading at the interface between the fiber and free-space optics of the telescope. The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has characterized a real-time photon-counting optical ground receiver system with an atmospheric fade emulation system. The receiver system is comprised of a fiber interconnect, an array of superconducting nanowire single photon detectors (SNSPDs), and a field programmable gate array (FPGA) based receive modem. Two fiber interconnect/detector architectures have been studied. One architecture uses a 70-mode photonic lantern coupled to seven single pixel SNSPDs. The other architecture uses a 10-mode few-mode fiber (FMF) coupled to a 15-pixel SNSPD array. The receiver system complies with the Consultative Committee for Space Data Systems (CCSDS) Optical Communications High Photon Efficiency Coding and Synchronization Standard, which uses serially concatenated convolutionally coded pulse-position modulation (SCPPM). The CCSDS standard is designed for use in low photon flux missions, including the Orion Artemis-II Optical (O2O) communications demonstration. The standard utilizes a convolutional symbol interleaver which can be resized to mitigate different fades. The fade emulation system employed in this work emulates scintillation-induced, pointing-induced, and coupling-induced fading. This paper gives an overview of the real-time optical receiver system and the fade emulation system. It presents tests results which show the impact of fading on the performance on the receiver. The test results show that in the presence of channel fading, the 70-mode photonic lantern outperforms the 10-mode FMF under higher (D/r_0=9) turbulence conditions due to high fiber-coupling-induced fading and fiber coupling loss on the 10-mode FMF. When operating in lower turbulence (D/r_0=4), the 10-mode FMF outperforms the 70-mode photonic lantern. The paper also shows a larger convolutional interleaver improves the system performance as long as the receiver does not lose acquisition.

optical communications↗

Spatial Mode-Diversity Optical Receivers for Free-Space Optical and Quantum Communications

We present an overview of spatial mode-diversity (SMD) receiver systems based on photonic lanterns for space-to-ground optical and quantum communications systems. Recent results are presented for direct-detection pulse-position modulated (PPM) and multi-Gbps coherent communications. We discuss designs for scalability in combination with integrated photonics.

Optical communications↗

Fiber-Detector Subsystem Loss Comparison for A Ground-Based Photon-Counting Optical Receiver

In this paper we present a comparative study of the losses associated with fiber-coupled single-photon detectors in two different configurations, each with the goal of receiving a pulsed-position modulated signal with a maximum data rate of 267 Mbps. First, we consider a 7x1 few-mode-fiber (FMF) photonic lantern coupled to seven individual superconducting nanowire single photon detectors (SNSPDs). In the second configuration we assess a single FMF coupled to a 16-channel monolithic SNSPD array. In each case we measure and compare combined fiber coupling, SNSPD blocking, and system efficiency losses under emulated atmospheric turbulence conditions. We address subsystem impact on link performance and analyze feasibility for future NASA lunar and deep-space optical communications missions.

Fiber optics↗

Fiber-Detector Subsystem Loss Comparison for A Ground-Based Photon-Counting Optical Receiver

A comparative study of the losses associated with fiber-coupled single-photon detectors in two different configurations, each with the goal of receiving a pulsed-position modulated signal with a maximum data rate of 267 Mbps. First, we consider a 7x1 few-mode-fiber (FMF) photonic lantern coupled to seven individual superconducting nanowire single photon detectors (SNSPDs). In the second configuration we assess a single FMF coupled to a 16-channel monolithic SNSPD array. In each case we measure and compare combined fiber coupling, SNSPD blocking, and system efficiency losses under emulated atmospheric turbulence conditions. We address subsystem impact on link performance and analyze feasibility for future NASA lunar and deep-space optical communications missions.

Fiber optics↗