Abstract: Disclosed is a system for coherent transient Stark switching for low power modulation of an infrared laser beam at a gigahertz rate and a nanosecond risetime. When a molecular frequency of a gas that has been excited by an electric field is shifted out of resonance relative to a laser beam by a coherent Stark pulse, the shifted excited molecular frequency will heterodyne with the laser frequency to give a beat signal having improved modulation depth and increased speed for use in space satellite communication.

Abstract: An arrangement for detecting low concentrations of molecular gases. A gaseous sample containing molecules of the gas to be detected is simultaneously subjected to two photon beams which, for example, may be generated by lasers. The wave length of the first photon beam corresponds to the energy separation between the ground electronic state and an excited electronic state of the molecular gas and the second photon beam contains energy in a wave length corresponding to the energy separation between the excited electronic state and the ionization limit of the molecule. Detection of the amount of ionization achieved is a measure of the concentration of the molecular gas in the sample. Simultaneous identification of the particular wave lengths causing the transition of the molecules from the ground energy state to the excited state provides an additional parameter identifying the molecules.