An Overview of Free Space Optics with Quantum Cascade Lasers

The article presents an overview of the work on quantum cascade lasers application in free space optical systems (Free Space Optics - FSO). There are discussed the main issues of the open-space laser communications and their practical construction. Comparative analyses of each FSO technology were performed. Brief description of quantum cascade (QC) lasers and some developments related to the use of these lasers in optical data link are also presented. In summary, the constructed models of FSO links with QC lasers are characterized

NIKEL: Electronics and data acquisition for kilopixels kinetic inductance camera

A prototype of digital frequency multiplexing electronics allowing the real time monitoring of microwave kinetic inductance detector (MKIDs) arrays for mm-wave astronomy has been developed. Thanks to the frequency multiplexing, it can monitor simultaneously 400 pixels over a 500 MHz bandwidth and requires only two coaxial cables for instrumenting such a large array. The chosen solution and the performances achieved are presented in this paper.Comment: 21 pages, 14 figure

Moving forward: Emerging themes in financial services technologies’ adoption

© 2015 by the Association for Information Systems. Financial services technologies (FST) are core to the continuous transformation of financial services organizations (FSO). To date, however, there has been a lack of empirical research into FST adoption against the backdrop of the recent financial crisis. In this paper, we re-examine how FSO are currently positioned to take advantage of emerging FST. Note that, in this paper, we look forward rather than provide a commentary on the state of the art in technology adoption research. We conducted this research by applying an exploratory qualitative study method: we analyzed interview transcripts from thirty recent interviews of FSO technology executives and CIOs by using a thematic network analysis tool. This analysis uncovered nineteen basic, eight organizing, and two global FST adoption research themes along with their links to FST adoption objectives, challenges, customer centricity, human resources, outsourcing, and overall IT strategy maintenance. This research has both practical and theoretical research implications and serves as a resource base for FSO and researchers to set future research priorities and directions. We intend for the emerging themes that we present in this paper to facilitate research directions by shedding light on the areas of greatest value and potential return in FST adoption

Adaptive probabilistic shaped modulation for high-capacity free-space optical links

Infrared free-space optics (FSO) provide an attractive solution for ultra-high-capacity wireless communications. However, the full potential of FSO is still being hindered by the apparent random fluctuations on the received optical power, which can be triggered by external factors such as atmospheric turbulence, weather instability, and pointing errors. Through the analysis of long-term experimental measurements, we identify the existence of significant time-domain memory in outdoor FSO links, which is found to be particularly strong under rainy weather conditions. Following this observation, we demonstrate that these memory effects can be effectively utilized to design accurate FSO channel estimation algorithms. Taking advantage of the arbitrary bit-rate granularity provided by probabilistic constellation shaping (PCS), and resorting to a simple moving average channel estimator, we demonstrate 400G+ transmission over a seamless fiber-FSO 55-m link with enhanced resilience towards adverse weather conditions. Comparing with unsupervised fixed modulation, we demonstrate a significant increase in average bit-rate (>35 Gbps) after continuous measurement over 3 hours, including raining periods

Frame Synchronization for FSO Links with Unknown Signal Amplitude and Noise Power

In this letter, we investigate the problem of frame synchronization in a free-space optical (FSO) communications link, where a known synch pattern is periodically embedded in the transmitted bitstream. The modulation format is on-off keying (OOK) and the electrical signal provided by the photo-detector is plagued by a mixture of thermal and shot noise with signal-dependent power. Due to atmospheric turbulence, channel attenuation can exhibit large random fluctuations, so that no prior knowledge of the signal level and noise variances is assumed. These parameters, together with the start-of-frame, are jointly estimated using a simplified maximum likelihood (ML) approach. Numerical simulations indicate that the proposed scheme is able to effectively exploit the presence of shot noise to improve its detection capability, and outperforms the standard frame synchronization method tailored for an AWGN channel with signal-independent noise power