Optical Signal Processing

The coherent time-stretch transform enables high-throughput acquisition of complex optical fields in single-shot  measurements. Full-field spectra are recovered via temporal interferometry on waveforms dispersed in the temporal near field. Real-time absorption spectra, including both amplitude and phase information, are acquired at 37 MHz.

L'estesa rete di torri costruite tra XII e XIV secolo nella Campagna Romana ci spinge a ritenere che questo tipo di edifici possa non aver avuto mera funzione difensiva. Omogenea distribuzione delle torri sul territorio e loro non casuale disposizione  - come dimostra il caso studio del Parco dell'Appia Antica (450 ettari circa) erano pensate per scorgersi a vicenda - consentono di ipotizzare che, sia pure accettando una pluralità di funzioni magari sin dall'origine, la scelta sia stata quella di monumenti di di segnalazione

Micro/nanostructure photonic devices offer a variety of enabling properties, including low power-consumption, cost-efficient, compact size, and reliability. These distinctive features have been exploited in a wealth of applications ranging from telecommunication and optical interconnect to photonic network on chip. In this paper, we review two main classes of micro/nanostructure photonic devices, to provide the kinds of functions for optical signal processing.

Focusing and guiding light into semiconductor nano-structures can deliver revolutionary concepts for photonic devices, which offer a practical pathway towards next-generation power-efficient optical networks. In this review, we consider the prospects for photonic switches using semiconductor quantum dots (QDs) and photonic cavities which possess unique properties based on their low dimensionality. The optical nonlinearity of such photonic switches is theoretically analysed by introducing the concept of a field enhancement factor. This approach reveals a drastic improvement in both power-density and speed, which is able to overcome the limitations that have beset conventional photonic switches for decades. In addition, the overall power consumption is reduced due to the atom-like nature of QDs, as well as the nano-scale footprint of photonic cavities. Based on this theoretical perspective, the current state-of-the-art QD/cavity switches are reviewed in terms of various optical nonlinearity phenomena that have been utilized to demonstrate photonic switching. Emerging techniques, enabled by cavity nonlinear effects such as wavelength tuning, Purcell-factor tuning and plasmonic effects, are also discussed.

We report the first demonstration of high bit rate signal processing by a fiber-based photonic wire. We achieve 160 Gb/s demultiplexing via four wave mixing in a 1.9 microm diameter photonic wire tapered from As(2)S(3) chalcogenide glass single mode fibre, with very low pump power requirements ( < 20 mW average power, 0.45 W peak power), enabled by a very high nonlinearity (gamma approximately 7850 W(-1) km (-1) ) and greatly reduced dispersion.

With the current technology revolution, underwater wireless sensor networks (UWSNs) find several applications such as disaster prevention, water quality monitoring, military surveillance and fish farming. Nevertheless, this kind of networks faces a number of challenges induced by the nature of the underwater environment and its influence on the network physical media. Therefore, the ultimate objective of this paper is to lay down the key aspects of the physical layer of the underwater sensor networks (UWSNs). It discusses issues related to the characteristics and challenges of the underwater communication channel, differences between terrestrial wireless sensor networks and UWSNs, and acoustic propagation models in underwater. The paper also surveys some of the underwater acoustic modems. This study is essential to better understand the challenges of designing UWSNs and alleviate their effects.

9th International Conference on Signal and Image Processing (SIGL 2022) is a forum for presenting new advances and research results in the fields of Digital Image Processing. The conference will bring together leading researchers, engineers and scientists in the domain of interest from around the world. The scope of the conference covers all theoretical and practical aspects of the Signal, Image Processing & Pattern Recognition.

In any country, warning text is described on the signboards or wall papers to follow by everybody. This paper present Myanmar character recognition from various warning text signboards using block based pixel count and eight-directions chain code. Character recognition is the process of converting a printed or typewritten or handwritten text image file into editable and searchable text file. In this system, the characters on the warning signboard images are recognized using the hybrid eight direction chain code features and 16-blocks based pixel count features. Basically, there are three steps of character recognition such as character segmentation, feature extraction and classification. In segmentation step, horizontal cropping method is used for line segmentation, vertically cropping method and bounding box is used for connected component character segmentation. In the classification step, the performance accuracy is measured by two ways such as KNN (K's Nearest Neivour) classifier and feature based approach of template matching on 150 warning text signboard images.

In recent years, reversible logic has emerged as a promising computing paradigm having application in low-power CMOS, quantum computing, nanotechnology and optical computing. Optical logic gates have the potential to work at macroscopic (light pulses carry information), or quantum (single photons carry information) levels with great efficiency. However, relatively little has been published on designing reversible logic circuits in all-optical domain. In this paper, we propose and design a novel scheme of Toffoli and Feynman gates in all-optical domain. We have described their principle of operations and used a theoretical model to assist this task, finally confirming through numerical simulations. Semiconductor optical amplifier (SOA)-based Mach–Zehnder interferometer (MZI) can play a significant role in this field of ultra-fast all-optical signal processing. The all-optical reversible circuits presented in this paper will be useful to perform different arithmetic (full adder, BCD adder) and logical (realization of Boolean function) operations in the domain of reversible logic-based information processing.