Active region

is the region in a medium where direct electron hole pair (EHP) recombination takes place. For LEDs it is the region where most EHP recombination takes place. In the laser diode it is the region where stimulated emissions exceeds spontaneous emission and absorption. It is the region where coherent emission dominates.

Active Surface

is area by which alternating field, light beam, sound and ultrasonic sound enters in the air.                                                                                                                                           

Active Switching Zone

is the area above the active surface where the sensor reacts to the approximation of damping material. and switches its output accordingly. ''This means that it changes its switching status''.


In control technology, where it is known as the controlling element, this is the counterpart to the Sensor . It converts electrical current signals into mechanical movement. It is used on closed-loop circuits as the final controlling element e.g. solenoid valve, motor or circuit breaker for intervention in process control.

Additive-pulse mode locking

Synonyms :
Coupled-cavity mode locking

also known as coupled-cavity mode locking, can be viewed as an intracavity interferometer. By solving the equation of motion of the two coupled cavities, a mathematical description of the self-starting mechanism is obtained. 

Adiabatic soliton compression

Adiabatic soliton compression techniques have attracted much attention to generate high-quality short-width pulse trains in the order of a few picose conds. In adiabatic soliton compression, a soliton pulse is compressed during propagation in a fiber the anomalous dispersion of which becomes weaker and weaker along the propagation direction.