Silicon-based optoelectronics: the key technology for miniaturization of optical communication and sensing systems

Expanding the use of physical degrees of freedom to employ spatial multiplexing of data in optical communication is considered to be the most disruptive and effective solution for meeting the capacity demand of the growing information traffic. Development of space division–multiplexing methods stimulated research on spatial encoding, detection, and processing of data, attracting interest from various fields of science. Here a passive all‐dielectric metasurface with near‐unity transmission is demonstrated that engineers spatial mode profiles, potentially of an arbitrary complexity. The broadband response of the metasurface covers all S, C, and L bands of fiber communications. Unlike conventional phase plates, the metasurface allows for both phase and polarization conversion, providing full flexibility for the mode engineering. The dielectric metasurface is employed for mode multiplexing in a free‐space optical communication system with an extinction ratio in excess of 20 dB over the whole C‐band with negligible penalty even for 100 Gb s−1 data transmission. These results merge two seemingly different fields, optical communication and metamaterials, and they suggest a novel approach for an ultimate miniaturization of mode multiplexers and advanced LiFi technologies.

Optical Wireless Communication (OWC) adopts laser beam as the carrier to deliver the message. It combines with the advantages of Microwave Communication and Fiber Optic Communication. The key technologies of OWC system includes source coding, channel coding, laser diode modulation, auto-alignment and channel. In this paper, the research progress on OWC in Xi'an University of Technology is introduced. The research on source coding involves in baseband modulation, frequency modulation, OFDM transmission and vertical layered space-time codes. The research on channel coding includes RS codes, Turbo codes, LDPC codes and so on. And the adaptive coding method is analyzed to meet the different channel characteristics. Propagation performance of laser is studied and bit error rate (BER) is measured under various weather conditions of rainy days, snowy days, foggy days, hazy days and so on. The experiment results show that applying channel coding methods can improve the system performance of OWC, especially under rainy, snowy, foggy weather conditions, the BER after decoding is up to 10^-6. Based on many years of research, the technologies of MIMO, OFDM and space-time coding are proved to be the key technologies that need to solve in OWC.

This paper is a survey on the optical fiber communication and optical networks. First, we show a historical perspective of optical fiber communication and the progress of optical networks. In addition, we give a rough classification of optical networks. Due to the development of optical fiber communication, the key technologies, such as photoelectron technology, optical transmission technology and optical switching technology, are also discussed. Then, we introduce the architecture and functions of Automatically Switched Optical Networks(ASON) as an example of intelligent optical networks. At last, a new concept of optical networks management and control, visual management and control, is described. An outlook on optical networks' future development can be seen in the paper as well.

With the escalation of heterogeneous data traffic, the research on optical wireless communication (OWC) has attracted much attention, owing to its advantages such as wide spectrum, low power consumption and high security. Ubiquitous optical devices, e.g. light-emitting diodes (LEDs) and cameras, are employed to support optical wireless links. Since the distribution of these optical devices is usually dense, multiple-input-multiple-output (MIMO) can be naturally adopted to attain spatial diversity gain or spatial multiplexing gain. As the scale of OWC networks enlarges, optical MIMO can also collaborate with network-level operations, like user/AP grouping, to enhance the network throughput. Since OWC is preferred for short-range communications and is sensitive to the directions/rotations of transceivers, optical MIMO links vary frequently and sharply in outdoor scenarios when considering the mobility of optical devices, raising new challenges to network design. In this work, we present an overview of optical MIMO techniques, as well as the cooperation of MIMO and user/AP grouping in OWC networks. In consideration of the challenges for outdoor OWC, key technologies are then proposed to facilitate the adoption of optical MIMO in outdoor scenarios, especially in vehicular ad hoc networks. Lastly, future applications of MIMO in OWC networks are discussed. This article is part of the theme issue 'Optical wireless communication'.

Light detection and ranging (LiDAR) and optical wireless communication (OWC) are in high demand and rapidly developing owing to the explosive growth of smart systems that require automotive and mobile devices. Optical phased arrays (OPA) have become a key technology in LiDAR and OWC owing to their nonmechanical beam steering capabilities. However, using separate LiDAR and OWC platforms in one system creates problems, such as spectrum congestion, resource consumption, and high complexity. We propose a dual-function OPA that enables LiDAR and OWC to function on a single platform based on the simultaneous amplitude and phase modulation of optically injection-locked semiconductor lasers. We numerically demonstrated that the primary LiDAR and secondary OWC function simultaneously by independent control of the main and side lobes in the OPA signal. The variation in side lobe levels is controlled at 20 or 25 dB to realize low- and high-level data for OWC function as well as maintaining the main beam LiDAR function. We successfully achieved wide-opening eye patterns of 10 Gbps data transmission of the OWC operation.

Graphene oxide (GO) was initially developed to emulate graphene, but it was soon recognized as a functional material in its own right, addressing an application space that is not accessible to graphene and other carbon materials. Over the past decade, research on GO has made tremendous advances in material synthesis and property tailoring. These, in turn, have led to rapid progress in GO-based photonics, electronics and optoelectronics, paving the way for technological breakthroughs with exceptional performance. In this Review, we provide an overview of the optical, electrical and optoelectronic properties of GO and reduced GO on the basis of their chemical structures and fabrication approaches, together with their applications in key technologies such as solar energy harvesting, energy storage, medical diagnosis, image display and optical communications. We also discuss the challenges of this field, together with exciting opportunities for future technological advances.

Abstract: Fiber Optic Communication system is a key element in modern day telecommunication network used all around the globe. Larger bandwidth signal transmission where data received with lowest possible delay serves as a big edge to both, the telecommunication industry and consumer. Recently, optical fiber communication technology has made great progress, where constantly exploring new technologies has greatly enhanced communications capabilities in the traditional sense. This paper gives an overview of fiber optic communication systems including their key technologies, and also discusses their technological trend towards the next generation. The recent developments in the area of fiber optic communication as well as the advances in different Fiber types, their properties, optical sources, detectors, system limitations and applications are also discussed in the paper.

Motivated by the looming radio frequency (RF) spectrum crisis, this paper aims at demonstrating that optical wireless communication (OWC) has now reached a state where it can demonstrate that it is a viable and matured solution to this fundamental problem. In particular, for indoor communications where most mobile data traffic is consumed, light fidelity (Li-Fi) which is related to visible light communication (VLC) offers many key advantages, and effective solutions to the issues that have been posed in the last decade. This paper discusses all key component technologies required to realize optical cellular communication systems referred to here as optical attocell networks. Optical attocells are the next step in the progression towards ever smaller cells, a progression which is known to be the most significant contributor to the improvements in network spectral efficiencies in RF wireless networks.

Underwater wireless optical communication (UWOC) has emerged as a key technology for next-generation underwater wireless data transmission. Semantic communication is regarded as a promising communication paradigm to improve the efficiency and robustness of UWOC systems. However, existing underwater wireless optical semantic communication (UWOSC) system lacks the capability to adapt the code rate to different channel states, leading to intelligence inadequacy and coding inefficiency. In this paper, we introduce environment semantics into the UWOSC system for the first time, and propose an environment semantics aided underwater wireless optical semantic communication (ESA-UWOSC) framework. Based on this framework, we develop a system leveraging computer vision and deep learning for adaptive rate transmission. The ESA-UWOSC system is realized by a channel state perception mechanism (CSPM) for extracting environment semantics from the channel environment image to obtain the channel gain, a link network (LinkNet) for enabling variable code rate transmission of source semantic information, and a prediction network (PreNet) for predicting the optimal code length that satisfies the transmission task requirement. The combined operation of these three modules enables the ESA-UWOSC system to actively perceive channel state and perform adaptive rate transmission accordingly. In a series of experiments conducted on an emulated UWOC experimental platform, the results show that the ESA-UWOSC system outperforms the baseline scheme, achieving superior performance with lower bandwidth consumption, especially in harsh channel environments. Moreover, the results also demonstrate that the ESA-UWOSC system can achieve adaptive rate transmission based on the perceived channel state to meet transmission task requirement.

Free Space Optical (FSO) Communications are foreseen as key enabler technology for future Terabits/s feederlink fixed satellite services. However, earth-space optical links suffer from several atmospheric impairments such as cloud blockage, aerosols scattering, molecular absorption and turbulence. More specifically, cloud blockage has a major impact on the availability of optical links. In order to achieve the required system capacity and availability, ground networks of multiple Optical Ground Stations (OGSs) are envisaged. This paper presents a comparison between a set of simulation tools which can be used to analyze the availability of optical ground networks for fixed satellite services with respect to cloudiness.

The National Aeronautics and Space Administration (NASA) is continuously working in furthering its space and aero communications capabilities required for the successful accomplishment of its aerospace missions. With the ever present demand for higher communication data rates and larger bandwidth required by future space exploration missions, optimization of the communications systems supporting such missions is necessary to ensure that critical scientific data and high definition video and imagery of human and robotic exploration is properly transmitted back to Earth. In the aeronautics side, the envisioned increase in aircraft volumes under the Urban Air Mobility (UAM) and Advanced Air Mobility (AAM) ecosystems could benefit from communications capabilities impervious to interference and free from spectrum limitations constraints. This work discusses examples of GRC’s ongoing technology development and integration efforts relevant to the aforementioned scenarios. In particular, the ability to increase the versatility, affordability, and reliability of ground-based optical receivers for space-to-ground communications will be presented. Our current activities on the development of highly secure airborne laser communications links augmented with Quantum Key Distribution (QKD) will also be discussed, as well as scenarios in which optical communications could be beneficial to UAM/AAM. The status of efforts in quantum communications, high rate optical networks, and on the development of current efforts to demonstrate integrated Radio/optical communications (iROC) will also be addressed.

SDH(Synchronous Digital Hierarchy) is one of the hot technology in optical fiber communication which has the large capacity and high data transmission rate, and it uses block frame structure to carry information. In this paper, a method of analyzing the structure of SDH frame by an off-line signal analysis software based on LabVIEW is presented. And this paper describes the implementation of lead-lag PLL(phase locked loop) in LabVIEW, which is the key technology used in the process of clock and data recovery.

Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

We demonstrate the possibility of using 3D‐printed, see‐through planar elements built with commercially available materials as fluorescent Optical Antennas (OAs) for fast Optical Wireless Communication (OWC). OWC represents a key technology in the forthcoming next‐generation communication services (6G), given its intrinsic combination of bandwidth (BW), security, and pervasiveness. In the Visible Light Communication (VLC) approach, ubiquitous white or colored LED sources can also be used as optical transmitters besides providing indoor/outdoor illumination and signaling, strongly fostering the implementation of the Internet of Things (IoT) paradigm. Here, the intrinsic optical properties (such as BW, field of View (FoV), and collection efficiency) of four different fluorescent slabs grown with commercial, non‐optical resins typically employed to realize transparent objects are fully characterized, unveiling for the first time their large potential as receivers in VLC applications. Complete VLC communication tests are reported, demonstrating attainable bit rates larger than 70 Mb s −1 with On‐Off Keying (OOK) modulation, which could be largely increased toward the Gb s −1 target exploiting high‐order modulation schemes. This work can have a profound impact toward the full‐fledged implementation of the IoT paradigm, showing that transparent 3D‐printed objects can be exploited as optical front ends in a new class of VLC and OWC receivers.

With the rapid growth of Internet traffic, user demand being gradually expanding rapidly, which makes people put forward higher requirements on the capacity of optical communication and the function of the optical layer. In this way, researchers are seeking for higher speed, higher quality and larger capacity optical communication networks. All optical wavelength conversion (AOWC) is the key technology to achieve high level all-optical networks. In addition, to further increase the network efficiency and decrease the blocking probabilities, the all optical wavelength conversion (AOWC) is needed to avoid wavelength contention for dynamic optical path switching at the nodes. In this paper, AOWC technology based on semiconductor optical amplifier (SOA) is investigated. including cross-gain modulation (XGM), cross-phase modulation (XPM) and four-wave mixing (FWM). The implementation, advantages and disadvantages of these schemes are compared and discussed. What is more, the prospects and future development of AOWC is also discussed.