In optics, optical bistability is an attribute of certain optical devices where two resonant transmissions states are possible and stable, dependent on the input. Optical devices with a feedback mechanism, e.g. a laser, provide two methods of achieving bistability.
- Absorptive bistability utilizes an absorber to block light inversely dependent on the intensity of the source light. The first bistable state resides at a given intensity where no absorber is used. The second state resides at the point where the light intensity overcomes the absorber's ability to block light.
- Refractive bistability utilizes an optical mechanism that changes its refractive index inversely dependent on the intensity of the source light. The first bistable state resides at a given intensity where no optical mechanism is used. The second state resides at the point where a certain light intensity causes the light to resonate to the corresponding refractive index.
This effect is caused by two factors
- Nonlinear atom-field interaction
- Feedback effect of mirror
Important cases that might be regarded are:
- Atomic detuning
- Cooperating factor
- Cavity mistuning
Applications of this phenomenon include its use in optical transmitters, memory elements and pulse shapers.
Optical bistability was first observed within vapor of sodium during 1974.[1]