Fluorescence pulse measurement and antibunched light generation by interferences

In the first part we propose a new scheme to measure the envelope or the width of ultrashort pulses with two-photon interference. We have applied this scheme to the measurement of envelope and the width of ultrashort light pulses, such as mode-locked dye laser pulses, scattered light of them from randomly distributed elastic scattering. centers, and femtosecond fluorescence pulse excited by such lasers. We found that the pulse envelope function can be measured in combination with or separately from the field correlation function. This is the first measurement of the intensity profile by interference of mutually incoherent light from independent sources. This scheme can be applied to wide wavelength regions with no limit in the time resolution at very low intensity levels of light. In the second part we report a few experiments to generate antibunched photons with parametric amplifiers. Following the antibunching which is explainable by the traditional particle picture of photons, another scheme is reported, that is, interference of bunched photons and coherent photons. In quantum mechanics this process is explained as antibunching due to destructive interference of two-photon states of incident fields.