Photon Statistics: Light Sources and Noise Properties

This lecture discusses various light sources and their associated noise properties, focusing on the characteristics of hot bodies, discharges, LEDs, and lasers. It begins with hot bodies, which emit incoherent light with a broad spectrum and low modulation rates. The lecture then covers discharges, which also produce incoherent light but with distinct spectral lines. The instructor explains the differences between LEDs and superluminescent LEDs, highlighting their modulation capabilities and power outputs. The discussion transitions to lasers, emphasizing their coherent and monochromatic nature, as well as their high modulation frequencies. The lecture introduces photon statistics, distinguishing between Poisson statistics for independent events and Bose-Einstein statistics for correlated events. The implications of optical excess noise are examined, particularly in relation to the fluctuation of optical power. The lecture concludes with a comparison of noise characteristics in different light sources, including black bodies and LEDs, and the impact of these properties on optical detectors, setting the stage for further exploration in subsequent lectures.