Optical Fourier Surfaces for Integrated Photonics

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nanotechnology

Background:

• Integrated photonics relies on miniaturized optical elements.
• Traditional lithography limits optical elements to binary height profiles.
• Grayscale fabrication offers enhanced control and efficiency.

Purpose of the Study:

• To demonstrate photonic integrated circuits using grayscale optical Fourier surfaces (OFSs).
• To explore the capabilities of wavy height profiles in silicon-on-insulator and thin-film lithium niobate.
• To create efficient and compact optical devices with advanced functionalities.

Main Methods:

• Utilizing grayscale fabrication techniques, specifically thermal scanning-probe lithography and dry etching.
• Designing and implementing intuitive schemes for OFS elements.
• Fabricating devices on silicon-on-insulator and thin-film lithium niobate platforms.

Main Results:

• Demonstrated sinusoidal Bragg reflectors in silicon waveguides with up to 44 dB extinction ratio.
• Fabricated high-quality factor cavities (1.6 × 10^5) in lithium niobate waveguides.
• Achieved second harmonic generation in lithium niobate utilizing high-Q cavities and nonlinear properties.

Conclusions:

• Grayscale OFS fabrication is a high-fidelity method for advanced integrated photonic devices.
• This technique enables the creation of efficient, compact devices with tailored optical responses.
• The demonstrated devices showcase potential for next-generation quantum and classical optical technologies.