Tunable narrow band optical reflector based on indirectly coupled micro ring resonators

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Materials Science (Silicon-on-Insulator)

Background:

• Compact and tunable reflective structures are crucial for advanced photonic integrated circuits (PICs).
• Existing solutions may lack the required narrow bandwidth or tunability for specific applications.
• Micro ring resonators offer a promising platform for wavelength-selective optical components.

Purpose of the Study:

• To present a novel narrow-band wavelength-selective optical reflector.
• To demonstrate tunability of the reflection wavelength using integrated micro heaters.
• To validate the device performance through experimental measurements and analytical modeling.

Main Methods:

• Implementation of a device by indirectly coupling two micro ring resonators.
• Utilizing silicon-on-insulator (SOI) technology for fabrication.
• Employing the transfer matrix method for analytical modeling and simulation.
• Electrically driving integrated micro heaters for wavelength tuning.

Main Results:

• Achieved a narrow bandwidth optical reflector with tunable single reflection wavelength.
• Experimental results showed good agreement with the analytical model.
• Measured average reflectivity of 0.55 over a 37 nm span, with a peak reflectivity bandwidth of ~50 pm (FWHM).
• Obtained a high quality factor (Q) of approximately 30,000.

Conclusions:

• The proposed indirectly coupled micro ring resonator configuration effectively realizes a tunable, narrow-band optical reflector.
• This device provides a viable alternative for compact, single-wavelength reflective functionalities in PICs.
• The demonstrated tunability and high Q factor are significant for wavelength-sensitive optical systems.