Crystal Optics: Properties and Applications

Ashim Kumar Bain

• Publisher: Wiley-VCH
• Year: 2019
• ISBN:
  9783527823024
• Edition: 1
• Topic: Scienze fisiche
• Subtopic: Meccanica

Reviews the properties and applications of photo-elastic, acousto-optic, magneto-optic, electro-optic, and photorefractive materials This book deals with the basic physical properties and applications of photo-elastic, acousto-optic, magneto-optic, electro-optic, and photorefractive materials. It also provides up-to-date information on the design and applications of various optoelectronic devices based on these materials. The first chapter of Crystal Optics: Properties and Applications covers the basic concepts of crystal optics, such as index ellipsoid or optical indicatrix, crystal symmetry, wave surface, birefringence, and the polarization of light. Chapter 2 reviews the physical phenomena of crystal optics in isotropic and crystalline materials. It describes in detail research information on modern photoelastic materials and reviews the up-to-date photoelastic device applications. Chapter 3 develops the underlying theory of acousto-optics from first principles, formulating results suitable for subsequent calculations and design. The fourth chapter describes the basic principles of magneto-optic effects and mode of interaction with magnetic materials. The fifth chapter provides an understanding of the physical phenomenon of the linear and quadratic electro-optic effects in isotropic and crystalline materials. The last chapter collects many of the most important recent developments in photorefractive effects and materials, and pays special attention to recent scientific findings and advances on photorefractive materials and devices. -Features up to date information on the design and applications of various optoelectronic devices
-Looks at the basic concepts of crystal optics, including the polarization of light, effects of reflection and transmission of polarization and light polarizing devices, and more
-Pays special attention to design procedures for the entire range of acousto-optic devices and various applications of these devices
-Provides research information on modern magneto-optic materials and reviews the up-to-date magneto-optic device applications?up to terahertz (THz) regime Crystal Optics: Properties and Applications is an excellent book for the scientific community working in the field, including researchers, lecturers, and advanced students.

1
Crystal Optics

1.1 Introduction

Crystal optics is the branch of optics that describes the behavior of electromagnetic waves in anisotropic media, that is, media (such as crystals) in which light behaves differently depending on the direction in which the light is propagating. The characteristic phenomena of crystals that are studied in crystal optics include double refraction (birefringence), polarization of light, rotation of the plane of polarization, etc.

The phenomenon of double refraction was first observed in crystals of Iceland spar by the Danish scientist E. Bartholin in 1669. This date is considered the beginning of crystal optics. Problems of the absorption and emission of light by crystals are studied in crystal spectroscopy. The effect of electric and magnetic fields, mechanical stress, and ultrasound waves on the optical properties of crystals are studied in electro‐optics, magneto‐optics, photoelasticity, acousto‐optics, and photorefractivity, which are based on the fundamental laws of crystal optics.

Since the lattice constant (of the order of 10 Å) is much smaller than the wavelength of visible light (4000–7000 Å), a crystal may be regarded as a homogeneous but anisotropic medium. The optical anisotropy of crystals is caused by the anisotropy of the force field of particle interaction. The nature of the field is related to crystal symmetry. All crystals, except crystals of the cubic system, are optically anisotropic.

1.2 Index Ellipsoid or Optical Indicatrix

In isotropic materials, the electric field displacement vector D is parallel to the electric field vector E, related by D = ɛ₀ɛ_rE = ɛ₀E + P, where ɛ₀ is the permittivity of free space, ɛ_r is the unitless relative dielectric constant, and P is the material polarization vector.

The optical anisotropy of transparent crystals is due to the anisotropy of the dielectric constant. In an anisotropic dielectric medium (a crystal, for example), the vectors D and E are no longer parallel; each component of the electric flux density D is a linear combination of the three components of the electric field E.

(1.1)

where i, j = 1, 2, 3 indicate the x, y, and z components, respectively. The dielectric properties of the medium are therefore characterized by a 3 × 3 array of nine coefficients {ɛ_ij} forming a tensor of second rank known as the electric permittivity tensor and denoted by the symbol ɛ. Equation (1.1) is usually written in the symbolic form D = ɛE. The electric permittivity tensor is symmetrical, ɛ_ij = ɛ_ji, and is therefore characterized by only six independent numbers. For crystals of certain symmetries, some of these six coefficients vanish and some are related, so that even fewer coefficients are necessary.

Elements of the permittivity tensor depend on the choice of the coordinate...