Post-Processing Trimming of Silicon Photonic Devices Using Femtosecond Laser.

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• Commercial silicon photonic fabrication has limited accuracy, causing performance degradation in sensitive devices.
• Passive silicon photonic devices are particularly challenging as they cannot be adjusted after fabrication.
• Existing methods struggle to address fabrication errors in mass-produced silicon photonics.

Purpose of the Study:

• To present a novel post-processing trimming method for compensating silicon photonic device fabrication errors.
• To demonstrate the effectiveness of femtosecond laser trimming for performance adjustment.
• To address the unmet need for post-fabrication tuning in mass production.

Main Methods:

• Utilized femtosecond laser post-processing to alter cladding equivalent refractive indices.
• Investigated tuning parameters: illuminating area, focusing position, emitting power, and scanning speed.
• Applied the method to micro-ring resonators and Mach-Zehnder interferometer switches.

Main Results:

• Successfully shifted resonant wavelengths of micro-ring resonators within their free spectral range.
• Achieved wavelength shifts by precisely controlling femtosecond laser parameters.
• Demonstrated improved phase balance in Mach-Zehnder interferometer switches.
• Observed only an acceptable increase in optical loss.

Conclusions:

• Femtosecond laser trimming is an effective and rapid method for post-processing silicon photonic devices.
• This technique offers a viable solution for compensating fabrication errors in mass production.
• The method allows for precise, on-demand performance tuning of photonic integrated circuits.