Light-induced unidirectional light switching.

We report the first observation of a unidirectionally emitting medium obtained by the method of Doppler compensation by velocity-dependent light shifts. The emission can be switched on by a pulse of laser light. The properties of this light-switching technique are experimentally demonstrated.

Picosecond laser-spectroscopy measurement of hydroxyl fluorescence lifetime in flames.

Data are reported for the first known application of picosecond laser spectroscopy to the measurement of collisional quenching rates by time-resolved laser-induced fluorescence in flames. Collisional quenching rates are important for the determination of species concentrations by laser-induced fluorescence. The collisional quenching lifetime following excitation of the R(2)(4) A(2)Sigma(+) (nu' = 0) ? X(2)II (nu'' = 0) transition was measured to be 1.8 nsec in the burned-gas region of an atmospheric-pressure, premixed methane-air flame.

Photon-counting statistics of pulsed light sources.

We report measurement of the photon-counting distributions of nanosecond-duration light pulses. Photon counting is performed on light sources with widely different photon statistics, such as (1) a Q-switched Nd:YAG-laserpumped dye laser operating well above threshold and producing single-mode nanosecond pulses, (2) the same laser operating close to threshold, and (3) a rotating ground-glass aberrator illuminated by the laser pulses of case (1). The method is particularly suitable for the investigation of the statistics of light generated by the nonlinear interaction of radiation with matter.