Low-loss c-axis oriented Zn_0.72Mg_0.28O nonlinear planar optical waveguides on silicon

Area of Science:

• Materials Science
• Optoelectronics
• Solid State Physics

Background:

• Development of novel materials for integrated photonics is crucial for advancing optical interconnects.
• Zinc Oxide (ZnO) based materials offer potential for nonlinear optical applications but require optimization for device integration.

Purpose of the Study:

• To develop a material platform of highly c-axis oriented Zinc Magnesium Oxide (ZnMgO) thin films for nonlinear planar waveguides and electro-optic modulators on Silicon (Si).
• To investigate the influence of Magnesium (Mg) content on film quality and nonlinear optical properties.
• To evaluate the performance of ZnMgO based waveguides for on-chip optical applications.

Main Methods:

• Fabrication of c-axis oriented Zn_1-xMg_xO thin films.
• Second harmonic generation (SHG) measurements.
• Maker-fringe analysis for nonlinear susceptibility determination.
• Propagation loss measurements in slab waveguides at 633 nm wavelength.

Main Results:

• Optimized Mg content in ZnMgO films significantly enhances film growth quality.
• The second-order nonlinear susceptibility tensor element χ₃₃ of annealed Zn_0.72Mg_0.28O is approximately 4.2 times larger than that of ZnO.
• Low propagation losses of 0.68 ± 0.09 dB/cm (TE0) and 0.48 ± 0.03 dB/cm (TM0) were achieved for annealed Zn_0.72Mg_0.28O/SiO₂ slab waveguides.

Conclusions:

• Highly c-axis oriented Zn_0.72Mg_0.28O thin films provide a promising material platform for nonlinear planar waveguides.
• The enhanced nonlinear optical properties and low propagation losses indicate significant potential for on-chip optical interconnects.
• This work demonstrates a viable route for integrating advanced nonlinear optical functionalities onto Silicon photonic platforms.