Equilibrium distribution functions are determined for fermions (e.g. electrons) and bosons (e.g. photons). The Saha–Boltzmann equation, the Maxwellian distribution, and relativistic Maxwell–Juttner distribution are derived. The relativistic equation of state for a distribution where particle velocities approach the speed of light is examined.

General structure of quantum cascade lasers: resonant tunnelling, minigap and miniband. Gain coefficient. Rate equations and threshold conditions. Output power, slope efficiency and wall-plug efficiency. Applications of quantum cascade lasers.

Semiconductor lasers: rate equations and threshold conditions for laser action. Confinement factor. Temperature dependence of the threshold current: characteristic temperature. Output power: external quantum efficiency and slope efficiency. Quantum well lasers. General structures of semiconductor lasers. Spectral and spatial characteristics of diode laser emission.

Radiative transfer, the Einstein A and B coefficients, emission and absorption coefficients, and Doppler line broadening are discussed. Continuum radiation emission coefficients are derived using the idea of virtual photon scattering. Inverse Compton scattering is treated in some detail. The radiation reaction force is examined.

Crystal, lattices and cells; Bravais lattice; the reciprocal lattice; electrons in a periodic crystal: Bloch’s theorem; momentum of an electron in a periodic crystal; effective mass; electrons and holes in a semiconductor; calculation of the band structure: tight-binding method and k·p method; bandstructure of Si, GaAs and GaN.

A table of Lorentz invariant parameters and grouping of parameters is presented.

Distributed feedback (DFB) lasers: general structure. Uniform and lambda/4-shifted gratings. Coupled-mode theory: coupling parameter; threshold conditions. DFB lasers with uniform grating; evaluation of oscillating frequencies and threshold gain. DFB laser with lambda/4-shifted grating. Distributed Bragg Reflector (DBR) lasers.

Relativistic collision kinematics is examined. Relativistic and non-relativistic collisional processes in plasmas are treated in detail.

The Lorentz invariance of the phase of light is discussed. The transformation between frames of electric and magnetic fields is determined. The transformation between frames of acceleration is determined. The effect on the angular range of light in a laboratory frame when emitted in a rapidly moving frame is discussed in some detail.

The chemical potential of electrons is discussed as a function of density and temperature, including effects of degeneracy and relativity.  It is shown that the chemical potential at all but the highest densities is negative.

The Lagrangian for a charge in electric and magnetic fields is presented. The acceleration of charges in particle accelerators, in laser-produced plasmas and in the production of cosmic rays is described. Emission from charges in magnetic fields is treated in some detail. Synchrotron radiation, undulators, and free electron laser radiation output is examined.

Born-von Karman boundary conditions; density of states in bulk materials, quantum wells, and quantum wires. Carrier statistics in semiconductors: Fermi-Dirac distribution function, electron and hole density in the conduction and valence bands. Nondegenerate semiconductors; effective density of states; intrinsic semiconductors. Mass-action law. Doped semiconductors: donors and acceptors; hydrogen-like model. Degenerate semiconductors. Quasi-Fermi levels in nonequilibrium systems. Charge transport in semiconductors. Diffusion current.

Expressions, plots, and asymptotic approximations for modified Bessel functions of the second kind used in the book.