Microwave engineering filter synthesis technique for coupled ridge resonator filters

Area of Science:

• Photonics and Integrated Optics
• Optical Filter Design
• Silicon Photonics

Background:

• Integrated optical circuits require versatile wavelength filters, but current designs offer limited control without complex techniques.
• Microwave engineering utilizes powerful coupled resonator filter synthesis, a concept challenging to translate to optics due to resonator spacing limitations.

Purpose of the Study:

• To adapt sophisticated microwave filter synthesis techniques for optical integrated circuits.
• To demonstrate the realization of advanced optical filter functionalities using coupled ridge resonators.

Main Methods:

• Arrangement of recently reported ridge resonance structures as closely spaced coupled resonators.
• Utilizing a common silicon slab with multiple parallel ridges, where each resonator's properties are controlled by geometric engineering.
• Rigorous simulation to design and analyze optical bandpass filters with specific responses (Butterworth, Chebyshev).

Main Results:

• Demonstrated the ability to achieve very close resonator spacing, overcoming a key limitation in optical filter design.
• Successfully designed high-order optical bandpass filters at a 1.55 μm center wavelength with Butterworth or Chebyshev responses.
• Analyzed the impact of non-ideal behaviors on the performance of the proposed optical filters.

Conclusions:

• Ridge resonance structures can be effectively employed as coupled resonators for advanced optical filter functionalities.
• This approach enables the translation of powerful microwave filter synthesis techniques to silicon photonics.
• The proposed method offers enhanced control and versatility for designing integrated optical filters.