FSO performance analysis of a metro city in different atmospheric conditions

In this article, a free-space-optics (FSO) model for a metro city based on real-time visibility data under different weather conditions is presented. Here, the relation between atmospheric attenuation and visibility value and its impact on the FSO performance is carried out. Also, the hybrid-SIM modulation technique is applied for the bit error rate (BER) improvement of the system. Here, Bhubaneswar (the capital of Odisha, India) is considered for the above analysis. The total attenuation, BER, and link margin are calculated for the FSO performance evaluation of Bhubaneswar city and these are simulated using Matlab. The simulation results show that the proposed hybrid-SIM modulation technique achieves about 2.9 dB of SNR improvement than the existing BPSK-SIM technique. Also, from the link margin analysis, it is observed that the sunny day is the most suitable for FSO link transmission. These results can be helpful to decide the FSO parameters and the FSO setup can be designed for any city.

Electro-optic spatial light modulator from an engineered organic layer

Tailored nanostructures provide at-will control over the properties of light, with applications in imaging and spectroscopy. Active photonics can further open new avenues in remote monitoring, virtual or augmented reality and time-resolved sensing. Nanomaterials with χ(2) nonlinearities achieve highest switching speeds. Current demonstrations typically require a trade-off: they either rely on traditional χ(2) materials, which have low non-linearities, or on application-specific quantum well heterostructures that exhibit a high χ(2) in a narrow band. Here, we show that a thin film of organic electro-optic molecules JRD1 in polymethylmethacrylate combines desired merits for active free-space optics: broadband record-high nonlinearity (10-100 times higher than traditional materials at wavelengths 1100-1600 nm), a custom-tailored nonlinear tensor at the nanoscale, and engineered optical and electronic responses. We demonstrate a tuning of optical resonances by Δλ = 11 nm at DC voltages and a modulation of the transmitted intensity up to 40%, at speeds up to 50 MHz. We realize 2 × 2 single- and 1 × 5 multi-color spatial light modulators. We demonstrate their potential for imaging and remote sensing. The compatibility with compact laser diodes, the achieved millimeter size and the low power consumption are further key features for laser ranging or reconfigurable optics.

Internet Connectivity: Is Free Space Optics the Solution?

During the Coronavirus disease 2019 pandemic era, poor internet availability hampered online activity, particularly in the sector of education in Malaysia. The most effective way to address this situation is through the construction of telecommunications towers. However, it takes time due to the significant costs involved. Outdoor use of FSO appears to be more advantageous due to the absence of licensing requirements and the high bandwidth it offers. However, there are limitations. We will explore these FSO restrictions in this paper.

Performance Evaluation of a 4 × 20-Gbps OFDM-Based FSO Link Incorporating Hybrid W-MDM Techniques

Free space optics (FSO) has been recognized as a crucial technique to meet the high-bandwidth requirements in future wireless information transmission links. It provides a feasible solution to the last-mile bottleneck problem due to its merits that include high-speed data transportation and secure and low-latency networks. Due to these merits, FSO is a reliable technology for future health-care and biomedical services like the transmission of biomedical sensor signals. But the main limiting factor in the data transmission employing FSO links is adverse atmospheric weather conditions. This research work reports the designing and simulative evaluation of the performance of a high-speed orthogonal frequency division multiplexing–based free space optics link by incorporating wavelength division multiplexing of two independent frequency channels (193.1 THz and 193.2 THz) along with mode division multiplexing of distinct spatial laser Hermite–Gaussian modes (HG01 and HG03). Four independent 20-Gbps quadrature amplitude-modulated data signals are transported simultaneously under different atmospheric weather conditions using the proposed link. Also, the link performance has been investigated for an increasing beam divergence angle.

Impact of Pointing Errors on the Performances of Double Rician FSO Channels

In this paper we will propose new analytically traceable probability density function (PDF) model for free space optics (FSO) turbulence, obtained as a generalization of double Ricean turbulence model, that encompasses both large-scale and small-scale turbulence eddy effects along by taking into account performance decreasing influence of misalignment introduced through boresight pointing error model. Consequently, after delivering the closed-form expressions for the newly introduced double FSO model, we obtain the analytical expressions for the bit error rate (BER) performance for the Double Rician distribution affected by misalignment. Numerical results will show the impact of system parameters on FSO link performance and we will provide full performance analysis. © 2021.

Survey on Optical Wireless Communications-Based Services Applied to the Tourism Industry: Potentials and Challenges

In this paper, we explore the potential applications of Optical Wireless Communications in the tourism industry, considering both indoor and outdoor scenarios and different transmission speeds. They range from high-speed atmospheric outdoor links (Free-Space Optics (FSO)) to indoor systems based on high-speed lighting networks (known under the trade name LiFi©) or low-speed services support the Internet of Things networks, using visible light (VLC) or IR emitters, with receivers based on either on classical photodiodes or in image sensors, known as Optical Camera Communications. The avant-garde applications of this technology have been studied focusing on three possible use scenarios: the traveler himself, in what we have called TAN (Tourist Area Network); the tourist facility, which includes not only the hotel but also leisure areas (theme parks, museums, natural protected areas) or services (restaurants, shopping areas, etc.); and the entire destination, which can be both the city or the territory where the tourist is received, within the paradigm of the Smart Tourist Destination (STD). In addition to the classic services based on radio frequency and wired broadband networks, these technologies will make it possible to meet the tourist’s challenging needs, the establishment, and the destination. Besides, they cover the services imposed by the new marketing services related to location or context and feed the big data systems used to study tourist behavior.