Wavelength tunable integrated add-drop filter with 10.6 nm bandwidth adjustability.

Area of Science:

• Photonics
• Integrated Optics
• Nanofabrication

Background:

• Optical add-drop filters are essential components in wavelength-division multiplexing (WDM) systems.
• Existing filters often lack tunability, limiting their flexibility in dynamic optical networks.

Purpose of the Study:

• To design and characterize a silicon-on-insulator (SOI) based add-drop filter with independently tunable bandwidth and central wavelength.
• To demonstrate the thermo-optic tuning mechanism for achieving desired filter characteristics.

Main Methods:

• Device fabrication using electron-beam lithography.
• Thermo-optic tuning implemented via integrated metal heaters fabricated by a lift-off process.
• Characterization of transmission bandwidth and central wavelength tuning performance.

Main Results:

• Demonstrated tunable transmission bandwidth from 1.1 nm to 11.7 nm over a 1555 nm to 1573 nm wavelength range.
• Achieved over 4 nm of central wavelength tuning.
• Identified metal heater breakdown current as the limiting factor for further wavelength tuning.

Conclusions:

• The developed SOI add-drop filter provides significant bandwidth and wavelength tunability.
• The thermo-optic tuning approach is effective for dynamic control of optical filter parameters.
• Further improvements may require addressing limitations in heater design or material properties.