Glossary

Single mode fiber optic: fiber optic enabling the propagation of only one transverse mode ( the fundamental mode )
Waist: position along the propagation axis where a laser beam has the smallest size
Elliptical beam: a beam in which « equi-intensity » curves in a plane perpendicular to the propagation axis are elliptical
Lens: optical component with two refractive surfaces axially symmetrical for redirecting the light in a controlled manner
Wavelength ( of a light wave ): distance between two consecutive identical states of the electric ( or magnetic ) field
Effective focal length: algebraic distance from the primary/secondary principal plane of an optical system to its front/back focal plane
Spatial mode: specific spatial distribution of the electromagnetic field in a plane perpendicular to the propagation axis of a light wave possibly emitted by a laser or possibly propagating in a waveguide ( like, for instance, a fiber optic ) - also called transverse mode
Transmission coefficient: ratio between transmitted radiation power (or intensity or amplitude) and incident radiation power (or intensity or amplitude)
Fiber optic: long cylindrical optical component guiding light
Coupling ratio ( fiber optics ): see « coupling efficiency »