Squeezing across two harmonic generations utilizing coupled nonlinear waveguide systems

Abstract This study investigates the squeezing properties of light across a two-octave system consisting of multichannel single-mode nonlinear waveguides with evanescent coupling. The focus is on the first, second, and fourth harmonics generation. We analyze different input combinations and coupling setups to gain insight into how they impact the level of squeezing. The results show that multiple initial inputs amplify the squeezing effect, while certain initialization setups help maintain squeezing at higher harmonic levels. When the waveguides are fully coupled in the first octave, there is a large increase in squeezing at the first and second harmonic. Reduced coupling leads to a drop in the level of squeezing. At the fourth harmonic frequency, instability is observed in all configurations, which hinders the accurate detection of squeezing. By optimizing the quantity and arrangement of interconnected waveguides, it is possible to improve the nonlinear frequency conversion and thus the level of squeezing. This research may enhance the advancement of quantum optical systems by emphasizing the significance of coupling interactions across two harmonic generations.