Impact of Second Harmonic Coupling on Squeezed Light in Dual Octaves Multichannel Waveguides

This study investigates the impact of second harmonic coupling on the performance and efficiency of a dual-octave nonlinear waveguide system. Comparative analysis of simulation data with and without second harmonic coupling shows significant enhancement in squeezing values and stability across all harmonics. Notably, the presence of second harmonic coupling enhances first harmonic squeezing from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{10}^{-\mathbf{5}}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{10}^{-\mathbf{3}}$</tex>, second harmonic squeezing from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{10}^{-\mathbf{9}}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{10}^{-\mathbf{3}}$</tex>, and stabilizes fourth harmonic squeezing at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{10}^{-\mathbf{7}}$</tex>. Furthermore, the second harmonic coupling improves frequency conversion efficiency and ensures uniform squeezing distribution across waveguides. The findings show the critical role of second harmonic coupling in optimizing nonlinear waveguide systems for enhanced stability, efficiency, and squeezing performance.