Laser Intensity Noise Measurement
Since laser intensity noise often sets the performance limit of an experiment, it is important to characterize it to get good results. When making this kind of measurement, a low-noise, high-sensitivity photoreceiver is invaluable. The New Focus™ line of photoreceivers offers the ideal solution for this application. Their combination of shot-noise limited performance, high conversion gain, and wide bandwidth enables noise measurements to be made simply and easily.The laser output is attenuated, so as to not saturate the photodetector, and focused onto the photoreceiver. It is important to be sure that the photodetector is not overfilled. This can lead to unwanted noise coupling as mechanical vibrations cause the photodetector to see varying amounts of laser light. These acoustic frequencies will give false peaks in the amplitude-noise spectrum.