Preface

Is photonics the new electronics?

If we compare the basic elements in electronics viz . the electron with the basic unit in photonics such as photon, soliton and plasmon, we find an uncanny similarity with device applications. This is reinforced if we go on further and compare other elements like electrical cables and optical fibres or plasmonic waveguides, electrical generators and lasers or masers, electric circuits and optical circuits and finally conventional transistors and optical transistors. It can be clearly inferred that photonics has clear analogues for all tools of electronics. It is due to these similarities that the photonic community believes that photonic devices will be able to replace electronic devices entirely.

In fact, even now, photonic devices are ubiquitous in fields like, biomedicine, where lasers are used to treat many diseases; aerospace technology, dealing with laser altimeters, laser radars, etc .; in engineering, where photonics is central to manufacturing MEMS and lasers are used for photonic devices, etc .; in information technology for data storage, optical switching, and data transmission using optical fibers among many other applications of practical importance. Such photonic devices encompass a diverse variety of materials like photonic crystals, nonlinear optical crystals like photorefractive crystals and liquid crystals, optical metamaterials, semiconductor laser materials, electro-optic and magneto-optic materials, photonic polymers, and photonic crystal fibers among many others.

In the present book, we present the latest trends and research in the broad field of photonics and photonic materials applications. The chapters are categorized as follows :

We shall first consider Photonic Crystals. Chapter 1 summarizes recent developments in the field of photonic crystals by presenting the utmost frequent and necessary optical devices established based on PCs such as optical logic gates, optical power splitters, polarization splitters, sensing devices, and lasers. In comparison to conventional photonic devices, these devices have greater efficiency and a small footprint. In Chapter 2 , a novel design for an all-optical XOR gate using 2D photonic crystals has been proposed and investigated. Initially, the XOR gate is designed and simulated by using the FDTD method. The proposed XOR logic is achieved without nano-resonators and then with nanoresonators to get enhanced performance metrics in the form of high contrast ratio. Chapter 3 investigates and studies the effect of hydrostatic pressure on the reflectance and transmittance properties of the one-dimensional PC containing germanium (Ge). They use the transfer matrix method to calculate the transmittance and reflectance spectra.

Plasmonics is an emerging and fast-growing branch of science and technology that focuses on the coupling of light to the free electron density in metals, resulting in strong electromagnetic field enhancement due to the confinement of light into sub-wavelength dimensions beyond the diffraction limit. Chapter 4 provides a comprehensive description of the theoretical approaches adopted to investigate the dispersion relation of graphene surface plasmons, types of graphene surface plasmons and their interactions with photons, phonons and electrons, experimental techniques to detect surface plasmons, the behaviour of surface plasmons in graphene nanostructures and the recent applications of graphene-based plasmonics.

Renewable energy is the future in a power-hungry world. Solar Cells and Materials are hence forth going to play a vital role in the energy sector. In Chapter 5 , the third generation solar cells, in regard to materials, production, fabrication process, energy payback time, efficiency and applications have been critically analyzed. Chapter 6 gives a brief overview of the recent research work on graphene in solar cell applications. It is notable that graphene has been used in heterojunction solar cells, GaAs solar cells, dye-sensitized solar cells, Perovskite solar cells, polymer solar cells, and organic solar cells and hence such a review will be useful for further research on graphene-based solar cells to achieve higher efficiency.

Nanophotonics is a component of the broad field of nanotechnology which studies the characteristics of light on nanometer scales. It can also be said to be a study of interactions of objects of nanometer dimensions with light. Chapter 7 and Chapter 8 focus on the recent developments in nanophotonics. The various materials used for nanophotonics, their properties and different applications have been elucidated quite comprehensively. Chapter 9 investigates the electro-optic characteristics of a heterogeneous nanostructure for graded fibre optic cables based on shortwave infrared light communication systems under several number of nanoscale well-thickness layers.

Some novel photonic materials are considered next. 2D materials are believed to be the future solution to various photonics and opto-electronic technologies including fiber laser. In Chapter 10 , the application of monochalcogenides, transition metal dichalcogenides and MXenes is reviewed from the viewpoint of fiber laser technology. It covers the fundamental knowledge about these materials, the operating principle of Q-switching and mode-locking, and the configuration of 2D materials as saturable absorbers. The utilization of these materials as saturable absorbers in a wide range of fiber laser systems including Ytterbium-, Erbium- and Thulium-doped fiber laser is also discussed. Smart materials are those materials whose properties are changed upon application of an external stimulus . Devices using smart materials might replace more conventional technologies in a variety of fields. Smart Materials are attractive due to their light weight, sensing capability, lower component size , and complexity combined with design flexibility, functionality and reliability.

Bragg Fibers have tremendous practical applications hence spanning a large body of research. In Chapter 11 , the propagation and dispersion properties of hollow-core Bragg fibre waveguides for both high and low refractive index contrasts of cladding materials are explored and compared. In Chapter 12 , attractive research is presented to review the biological motivation behind the development of multilayer photonic nanostructure and various types of fuel adulteration detection optical sensors using various sensors-based techniques and compare with the Bragg Metal-Polymer nanocomposite optical sensor.

Silicon photonics is an area that relates to the investigation of photonic systems using silicon as an optical medium. Silicon photonics allows for high yield and complex integration with large processing, packaging, and testing availability. Chapter 13 analyzes different approaches to modeling fabrication variations in photonic integrated circuits, such as Monte Carlo, Stochastic Collocation, and Polynomial Chaos Expansion.

Finally, Chapter 14 gives a comprehensive review of different types of smart materials, their preparation, characteristics and applications.

In summary, we would like to state that the book tries to give a snapshot of current exciting research going on in the field of photonics incorporating different types of photonic materials. Photonics and photonic materials are a veritable ocean of which this is a humble attempt to sample a drop. We hope that this piques the interest of new researchers across the world and that they are encouraged to pursue research work in this fascinating field of photonics. In addition, we are hopeful that the book proves useful for scientists, university professors and industry professionals with a keen interest in photonics.