<title>Squeezing of radiation field in multiphoton processes</title>

Abstract

Squeezing of electro-magnetic field, which is a purely quantum phenomenon has attracted considerable attention owing to its low noise property with applications in high quality telecommunication. This quantum effect is expected to manifest itself in optical processes in which the nonlinear response of the system to the radiation field plays an important role. In this paper squeezing of electro- magnetic field in some multi-photon processes are investigated under short-time approximation. The processes studied include Raman and hyper Raman processes and sum- frequency generation. The coupled Heisenberg equations of motion for field operators are set up and solved under short-time approximation. The occurrence of squeezing of field is investigated using the required conditions of squeezing in each of the cases. The squeezing is found to exist in the fundamental mode and the squeezing in the generated field depends on squeezing in fundamental mode. Squeezing in higher order amplitudes are also studied. This corresponds to the squeezing of the variables which describe the real and imaginary parts of square and cube of the complex amplitudes of the radiation field. The higher order multimode sum squeezing of radiation field is dealt with for harmonic and sum frequency generation. It s shown that squeezing in the sum frequency field depends directly on the sum squeezing of fundamental modes. The results can be utilized in selecting a suitable process which will generate a radiation field with optimum squeezing and can be useful in high quality telecommunication.