Available online at www.scholarsresearchlibrary.com Scholars Research Library Archives of Physics Research, 2011, 2 (4):11-17 (http://scholarsresearchlibrary.com/archive.html) ISSN : 0976-0970 CODEN (USA): APRRC7 11 Scholars Research Library Dimensionless Intensity in the Semiclassical theory of Laser, Electric Field inside a Fabry-Perot Cavity and Voltage in a Triode Oscillator Circuit 1 J. Saikia, 2 H. Saikia, 3 R.K. Dubey* and 4 G.D. Baruah 1 Department of Physics, J.B. College, Jorhat, Assam 2 Department of Physics, Majuli College, Majuli, Jorhat, Assam 3 Institute of Education-Haldia,West Bengal 4 Centre for Laser and Optical Science, New Uchamati, Doom Dooma ______________________________________________________________________________ ABSTRACT The present work reports an analogy in three different topics appearing in the semiclassical theory of laser, Fabry Perot Cavity and triode oscillator circuit. We have shown that the buildup of the parameter dimensionless intensity in the semiclassical theory and the buildup of electric field inside a Fabry Perot cavity bear a striking similarity. In this connection Vander Pol’s triode oscillator circuit is also discussed. ______________________________________________________________________________ INTRODUCTION The present work is concerned with a comparative study between the buildup of dimensionless intensity in the semiclassical theory of laser and the buildup of electric field due to multiple reflections inside a Fabry Perot cavity. We have also brought under our discussion the buildup of voltage in a triode oscillator circuit. It is worthwhile to note that this type of work has not been reported earlier. An analogy between spatial hole burning and the intensity contour of the beams multiple reflections inside Fabry Perot cavity was established in an earlier work [1]. Recently [2] the subject of spatial hole burning, multiple reflections inside a Fabry Perot cavity and squeezed states of light have been discussed and in all the cases worthwhile analogy among the three phenomena has been noted. We also note here that in many ways some phenomena of physics appearing under different contexts are quite analogous. As for example the comparison between the laser near threshold and matter near a phase transition was developed by DeGiorgio and Scully (3) long back. 2. BUILD UP OF DIMENSIONLESS INTENSITY The dimensionless intensity is an important parameter obtained in the semiclassical theory of laser (4, 5). The parameter is defined as 2 2 1 2 n n a b I γγ ℘ = Ε 