Nonclassical light in symmetric nonlinear directional coupler

Kishore Thapliyal, Anirban Pathak, Biswajit Sen +1 more

Natalia Korolkova, Jan Peřina

Gagik Yu. Kryuchkyan, Karen V. Kheruntsyan

R. Vilela Mendes

Mohd Syafiq M. Hanapi, Abdel-Baset M.A. Ibrahim, Rafael Julius +2 more

Possible squeezed states generated in a three-waveguide nonlinear coupler operating with second harmonic generation is discussed. This study is carried out using two well-known techniques; the phase space method (based on positive-P representation) and the Heisenberg-based analytical perturbative (AP) method. The effects of key design parameters were investigated under various conditions, including full frequency matching, symmetrical and asymmetrical waveguide initialization, and both codirectional and contr-adirectional propagation. The system consistently produced long-lasting oscillatory squeezed states across all three waveguides, even when only one waveguide was pumped with coherent light while the others were in a vacuum state. Also, the performance and capacities of both methods are critically evaluated. For low levels of key design parameters and in the early stages of evolution, a high level of agreement between the two methods is noticed. In the new era of quantum-based technology, the proposed system opens a new avenue for utilising nonlinear couplers in nonclassical light generation.

Jan Peřina

We investigate both codirectional and contradirectional nonlinear couplers composed of two nonlinear waveguides operating by second- and third-order nonlinear optical processes. We take into account possible mismatches inside the waveguides and between them. Quantum statistical characteristics, such as photon number distribution, its factorial moments, quadrature and integrated intensity variances and quadrature uncertainty product demonstrate generation and transmission of nonclassical light in nonlinear couplers. Incident beams are assumed to be coherent, squeezed and mixed with external noise. Nonclassical behavior of beams generated by the nonlinear waveguides can be transferred to linear waveguides and controlled by linear signal and by linear and nonlinear mismatches. In the contradirectional regime of propagation asymptotic nonclassical states can be obtained.