Role of the parametric and Raman processes in the generation of the second axial Stokes component of the stimulated Raman scattering

Abstract

thirty seconds (determined by the setting of VRJ, which allows condenser C2 to charge up to its full high voltage, V2 ikes and relay RLB operates:(i) opening RLB, and releasing relay RLA;(ii) closing RLB,. 3. Closure of RLB, applies a negative pulse to the control grid of the cold cathode tetrode V,, as a result of which the anode to cathode path immediately becomes conducting, and condenser C8 discharges through the primary of the ignition coil TR4. This produces in the secondary a damped oscillatory transient with an initial highly positive peak which, applied to the trigger electrode, flashes the discharge tube.4. Release of relay R L A restores the negative bias to V, $0 that the ax. energized relay RLB is released, and, after a short interval for recharging C8, the circuit conditions prior to operation of SW3 are resumed.A two-minute thermal delay switch S W, prevents application of anode voltage to the gas triode V2 until its heater has warmed up.

Analysis of the 2nd Stokes wave generation through stimulated Raman scattering in hydrogen gas under four-wave mixing conditions

“…For instance it is possible to convert visible radiation into IR light using the 2nd Stokes emission. In literature many papers have shown that the Raman generation of the 2nd Stokes wave is stimulated by mixing processes [1][2][3][4][5][6][7][8][9]. The mixing effect on the onset of the 2nd Stokes generation has been theoretically calculated and experimentally observed in [9], in conditions where no annular wave formation was detected because of high pressure and weak focusing.…”

“…In literature many papers have shown that the Raman generation of the 2nd Stokes wave is stimulated by mixing processes [1][2][3][4][5][6][7][8][9]. The mixing effect on the onset of the 2nd Stokes generation has been theoretically calculated and experimentally observed in [9], in conditions where no annular wave formation was detected because of high pressure and weak focusing. In that case the mixing effect induces an ''off-phase" seed radiation at the 2nd Stokes frequency much larger than the background one, that produces a lowering of the 2nd Stokes threshold, as observed in [5,6,9].…”

“…The mixing effect on the onset of the 2nd Stokes generation has been theoretically calculated and experimentally observed in [9], in conditions where no annular wave formation was detected because of high pressure and weak focusing. In that case the mixing effect induces an ''off-phase" seed radiation at the 2nd Stokes frequency much larger than the background one, that produces a lowering of the 2nd Stokes threshold, as observed in [5,6,9]. Cheng and Kobayashi [8] demonstrated that, by using a single mode TEM 00 gaussian pump, the mixing process induces a multimode 2nd Stokes emission, while other papers reported a clear annular emission [1,5].…”

“…With respect to the standard expression of the process (see for example [8]), the equations have been rearranged as in [6,9] to express the evident fact that the mixing stimulates simultaneously both the 0 ? 1 and the 1 ?…”

Picosecond pulse generation in a benzene raman generator amplifier system

“…Under intense pumping conditions the stimulated Raman scattering depletes the pump laser and the generated Stokes light becomes the pump source of higher order Stokes light generation by the processes v sn~* v s«+i+ v v [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Four photon mixing processes like v s l + v sl -+ v L + v S2 may contribute to the higher order Stokes light generation if the corresponding phasematching angles are small [15][16][17]. Parametric Stokes anti-Stokes coupling [1][2][3][4][5], v L +v L ->v sl + v AS1 , and higher order anti-Stokes coupling, like v AS/l + v L ->v sl…”