Kassahun, Fesseha (PhD)Melaku, Menwuyelet2018-06-292023-11-092018-06-292023-11-092012-02http://10.90.10.223:4000/handle/123456789/4866With the aid of c-number Langevin equations, we have calculated the Q-functions for the two-mode coherent and subharmonic cavity light beams. Applying the input-output relation, we have obtained the Q-functions for the two-mode coherent and subharmonic output light beams. We have then determined the Q-function for the superposition of these two output light beams. With the help of the pertinent Q-functions for the output light, we determined the output photon statistics. We have calculated the mean and vari- ance of the photon number sum and di erence for the two-mode coherent output light, the two-mode subharmonic output light, and the superposed two-mode coherent and sub- harmonic output light beams. We have found that photon stastics of the two-mode coherent output light is Pois- sonian and that of the subharmonic output light is super Poissonian. And the output signal and idler modes are separately in a chaotic states. In addition, the mean photon number for the superposed output light turns out to be the sum of the mean photon number of the two-mode coherent output light and that of the two-mode subharmonic output lightenTwo-Mode CoherentThesis