Asymmetric Group Velocity Dispersion and Pulse Distortion in a Uniform Fiber Bragg Grating

In a uniform fiber Bragg grating, if the input signal is a Gaussian pulse the dispersion is zero near center wavelength and becomes appreciable only near the band edges and side lobes of the reflection spectrum. However for chirped Gaussian pulses, group velocity dispersion and the reflected light must become asymmetric. Here the chirped Gaussian pulses can be treated as a symmetric but nonuniform input signal. The present paper describes that for the case of symmetric Gaussian pulse, the group velocity dispersion and pulse distortion remain symmetric however strong the grating may be. On the other hand both tend to be more asymmetric for the case of strong grating while the input signal is symmetric with nonuniform shape

Optically Multiplexed Systems: Wavelength Division Multiplexing

Optical multiplexing is the art of combining multiple optical signals into one to make full use of the immense bandwidth potential of an optical channel. It can perform additional roles like providing redundancy, supporting advanced topologies, reducing hardware and cost, etc. The idea is to divide the huge bandwidth of optical fiber into individual channels of lower bandwidth, so that multiple access with lower-speed electronics is achieved. This chapter focuses on one of the most common and important optical multiplexing techniques, wavelength division multiplexing (WDM). The chapter begins with a quick historical account of the origin of optical communication and its exponential growth following the invention of erbium-doped fiber amplifier (EDFA) leading to the widespread adoption of WDM. Alternate multiplexing schemes are also briefly discussed, including time-division multiplexing (TDM), space-division multiplexing (SDM), etc. A typical WDM link and its components are then discussed with special focus on WDM Mux/demultiplexer (DeMux). Further, certain challenges in this field are addressed along with some potential solutions. The chapter concludes by highlighting some features and limitations of optically multiplexed WDM systems

The Quantum Internet: A Hardware Review

In the century following its discovery, applications for quantum physics are opening a new world of technological possibilities. With the current decade witnessing quantum supremacy, quantum technologies are already starting to change the ways information is generated, transmitted, stored and processed. The next major milestone in quantum technology is already rapidly emerging -- the quantum internet. Since light is the most logical candidate for quantum communication, quantum photonics is a critical enabling technology. This paper reviews the hardware aspects of the quantum internet, mainly from a photonics perspective. Though a plethora of quantum technologies and devices have emerged in recent years, we are more focused on devices or components that may enable the quantum internet. Our approach is primarily qualitative, providing a broad overview of the necessary technologies for a large-scale quantum internet.Comment: 38 pages, 1 tabl

Integrated Photonic Platforms for Quantum Technology: A Review

Quantum information processing has conceptually changed the way we process and transmit information. Quantum physics, which explains the strange behaviour of matter at the microscopic dimensions, has matured into a quantum technology that can harness this strange behaviour for technological applications with far-reaching consequences, which uses quantum bits (qubits) for information processing. Experiments suggest that photons are the most successful candidates for realising qubits, which indicates that integrated photonic platforms will play a crucial role in realising quantum technology. This paper surveys the various photonic platforms based on different materials for quantum information processing. The future of this technology depends on the successful materials that can be used to universally realise quantum devices, similar to silicon, which shaped the industry towards the end of the last century. Though a prediction is implausible at this point, we provide an overview of the current status of research on the platforms based on various materials.Comment: 48 pages, 3 figure

A Unique Filter-Preserver Device for Digital Photonic Circuits

We discuss micro ring resonator based optical logic gates using Kerr-type nonlinearity. Resonant wavelength selectivity is one key factor in achieving the desired gate. Based on basic gates like AND gate, OR gate etc. We proceed to propose a 3-bit binary adder circuit.Due to the presence of more than a single wavelength, the system gets complicated as we increase the number of components in the circuit. Hence it has been observed that for efficient designing and functioning of digital circuits in optical domain, we need a device which can give single wavelength output, filtering out all other wavelengths and at the same time preserve the digital characteristics of the output. We propose such filter-preserver device based on micro ring resonator

Electromagnetic analysis of novel class of multiple core/multiple clad step index single mode optical fiber by analytical means

General propagation properties and universal curves are given for double clad single mode fibers with inner cladding index higher or lower than the outer cladding index, using the parameter: inner cladding/core radii ratio. Mode cut-off conditions are also examined for the cases. It is shown that dispersion properties largely differ from the single clad single mode fiber case, leading to large new possibilities for extension of single mode operation for large wavelength tange. Paper demonstrates that how substantially we can extend the single mode operation range by using the raised inner cladding fiber. Throughout we have applied our own computations technique to find out the eigenvalue for a given modes. Detail derivations with all trivial mathematics for eigenmode equation are derived for each case. Paper also demonstrates that there is not much use of using depressed inner cladding fiber. We have also concluded that using the large inner cladding/inner core radius we can significantly increase the single mode operation range for the large wavelength region. (C) 2015 Elsevier GmbH. All rights reserved

Comparative analysis of ultra-compact few-mode photonic wires on LNOI and SOI platforms

Parametric comparison of ultra-compact few-mode waveguides of three types (strip, rib, and buried) on thin-film Lithium Niobate On Insulator (LNOI) and SOI platforms is presented. Performance of waveguides is compared in terms of waveguide cross-sectional area, mode loss, dispersion, mode-hybridization and power confinement for both quasi-transverse electric (qTE) and quasi-transverse magnetic (qTM) modes. It is found that LNOI waveguides exhibit lower dispersion with physical dimensions comparable to that of SOI waveguides. The results are vital in choosing an optimum configuration of few-mode waveguides which is crucial for designing few-mode devices in mode-multiplexing schemes