Acousto-optic Q switches

When placed inside a laser cavity, an acousto-optic Q-switch can be used to control the amount of light circulating within the resonator via the acousto-optic effect.                       

Acousto-optic tunable filters (AOTF)

AOTF are used to rapidly and dynamically select a specific wavelength from a broadband or multi-line laser source. As the applied RF frequency is varied, the transmitted wavelength changes, “tuning” the wavelength of the beam or image in tens of microseconds or less.

Activation energy

is the potential energy barrier that prevents a system from changing from state to another. For example, if two atoms A and B get together to form a product AB, the activation energy is the potential energy barrier against the formation of this product. It is the minimum energy which the reactant atom or molecule must have to be able to reach the activated state and hence form the product. The probability that a system has an energy equal to the activation energy is proportional to the Boltzmann factor: exp (-EA/KT), where EA is the activation energy, K is the Boltzmann constant and T is the temperature (Kelvins).

Active device

is a device that exhibits gain (current or voltage or both) and has a directional function. Transistors are active devices whereas resistors, capacitors and inductors are passive devices

Active fibers

Active fibers are doped with rare elements like Er, Tm or Yb which perform the stimulated emission by transforming the laser diode pumping power to the laser power.                  

Active Mode Locking

The task of mode-locking is to get as many of the longitudinal modes. lasing in a phase synchronous fashion, such that the superposition of all modes represents a pulse with a spatial extent much shorter than the cavity. The pulse will then propagate at the group velocity corresponding to the center frequency of the pulse.