In optics, an optical medium is material through which light and other electromagnetic waves propagate. It is a form of transmission medium. The permittivity and permeability of the medium define how electromagnetic waves propagate in it.

Properties

The optical medium has an intrinsic impedance, given by

are the electric field and magnetic field, respectively. In a region with no electrical conductivity, the expression simplifies to:

For example, in free space the intrinsic impedance is called the characteristic impedance of vacuum, denoted Z0, and

is the frequency is the wavelength of the electromagnetic waves. This equation also may be put in the form

is the angular frequency is the wavenumber of the wave. In electrical engineering, called the phase constant.

The propagation velocity of electromagnetic waves in free space, an idealized standard reference state (like absolute zero for temperature), is conventionally denoted by c0:

1. is the electric constant is the magnetic constant.

For a general introduction, see Serway For a discussion of synthetic media, see Joannopoulus.

See also

• Čerenkov radiation

• Electromagnetic spectrum

• Electromagnetic radiation

• Optics

• SI units

• Free space

• Metamaterial

• Photonic crystal

• Photonic crystal fiber

Notes and references