Flame pumping and infrared maser action in CO2

G. J. Troup

John J. Ehrlich, C. M. Bowden, D. W. Howgate +3 more

Fritz Kurt Kneubühl, Damien P. Scherrer, Joachim Knittel +2 more

In order to produce ultrashort far-infrared (FIR) laser pulses we have investigated the superradiance and Raman emission of various molecular transitions optically pumped with the pulses of 10 micrometers -hybrid- or high-pressure single-mode-CO2 lasers truncated within 10 ps. Furthermore we have truncated directly the FIR laser pulses with the first FIR plasma shutter. In our experiments we have observed new phenomena which include e.g. new interrelations between superradiance, swept-gain superradiance and Raman emission, anticorrelated fluctuations of pump radiation versus FIR emission, first optical free induction decay of 10 micrometers -CO2-laser pulses with FIR emitting molecular gases. Finally, we have proved the first spontaneous infrared solitons in stimulated far-infrared Raman scattering on NH3. We have observed solitons in the depletion region of the infrared pump radiation with corresponding dark solitons in the Stokes pulses and detected the laser phase change connected with the soliton generation.

John Morrison

Kōichi Shimoda

In the case when the pumping transition in a three-level system of a molecule does not exactly coincide with the output frequency of a maser oscillator, four different types of operation at off-resonance of the three-level maser detector are discussed. At first the use of pressure broadening is considered; secondly a method which observes the double-quantum transition and thirdly the other method which measures a change in population caused by the double-quantum pumping are considered, and finally the level shift due to the far-infrared input is considered. It is found that the third method of double-quantum pumping in which three waves are involved is the most sensitive. The minimum detectable power of order 10-6W/cm2 with the resolving time of about 10-6s is expected in detecting the maser output at the far-infrared which differs from the resonant frequency of the detector by as large as 10 GHz.

Damien P. Scherrer

We report on new effects achieved by optical pumping of far-infrared superradiance and Raman emissions in CH3F, CH3CN, D20, NH3 by rapidly truncated 101.1m CO2 laser pulses. These phenomena include drastic reduction of far-infrared-pulse duration, competition of forward superradiance and Raman emission, stability of backward superradiance, periodic back-and-forth fluctuation of the A-like three-level molecular system.