Noise Eaters | previous | next | feedback |
Definition: devices for reducing the intensity noise of an optical beam by automatically adjusting the degree of power attenuation
A noise eater is a device made for reducing the intensity noise in a laser beam. The principle of operation is that the optical power is reduced with an electrically controllable attenuator, and the control signal is derived from the input power (→ feedforward scheme) or the output power (→ feedback scheme) as measured e.g. with a photodiode. This makes it possible to stabilize the laser power, i.e., to decrease intensity noise.
The most common approach is that based on an electronic feedback loop, e.g. of a PID type. An electro-optic modulator can be used to control the power throughput with a high servo bandwidth. Proper design of the feedback electronics is vital for achieving an effective noise suppression over a large bandwidth.
See also: laser noise, intensity noise, stabilization of lasers
Categories: fluctuations and noise, photonic devices
