Design of optically path-length-matched, three-dimensional photonic circuits comprising uniquely routed waveguides

Area of Science:

• Photonics
• Optical Engineering
• Nanofabrication

Background:

• Designing integrated photonic circuits with matched optical path lengths is crucial for interferometric applications.
• Existing methods often struggle with complex routing and precise path-length control in three dimensions.

Purpose of the Study:

• To develop and demonstrate a method for designing physically path-length-matched, three-dimensional (3D) photonic circuits.
• To address the challenge of uniquely routing all waveguides from input to output in such circuits.

Main Methods:

• A novel design methodology for 3D photonic circuits was developed.
• Circuit elements were fabricated using the femtosecond laser direct-write technique.
• Interferometric methods were employed to verify optical path-length matching.

Main Results:

• The fabricated 3D photonic circuits achieved optical path-length matching within 45 μm.
• This level of precision is suitable for many interferometric measurement applications.
• The unique waveguide routing strategy was successfully implemented.

Conclusions:

• The described method enables the design of path-length-matched 3D photonic circuits.
• Femtosecond laser direct-write fabrication is a viable technique for realizing these circuits.
• The demonstrated path-length matching accuracy meets requirements for various interferometric applications.