Once saturated, the inductance of the saturable reactor drops dramatically. A quantum well can be fabricated as a saturable absorber utilizing its saturable absorption property. Saturable absorbers are useful in laser cavities. The saturable inductor operates into its saturation region. It has an absolute bioavailability of about 50%, with evidence of a saturable first-pass effect. Saturable inductor current sensor is based on the detection of an inductance change. The limited availability of CYP2D6 means perhexiline metabolism is a saturable process. Saturable absorbers are widely used in passively mode locking lasers. A commonly used device to achieve this is a saturable absorber. Graphene saturable absorbers have also been used for mode locking fiber lasers. Saturable reactor amplifiers were used for control of power to industrial furnaces. A saturable reactor exploits saturation of the core to control alternating current. Free pantothenic acid is absorbed into intestinal cells via a saturable, sodium-dependent active transport system. A saturable absorber is an optical device that exhibits an intensity-dependent transmission. Ken Olsen's saturable switch used ferrites and was a current operated switch.