Design of SiON-based grating-assisted vertical directional couplers

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Waveguide Technology

Background:

• Coupling dissimilar waveguides is crucial for integrated photonic circuits.
• Grating-assisted couplers offer a method for efficient light transfer.
• Silicon oxynitride (SiON) is a suitable material for optical applications.

Purpose of the Study:

• To design a SiON-based grating-assisted codirectional coupler for dissimilar waveguides.
• To analyze the performance of the coupler for TE and TM polarizations.
• To optimize design parameters for efficient and polarization-independent coupling.

Main Methods:

• Accurate numerical methods were employed for design and simulation.
• Coupling length and efficiency were calculated.
• The influence of grating height, slab thickness, and gap thickness was investigated.
• Simulations were performed at a wavelength of 1.54 µm.

Main Results:

• Efficient vertical couplers with up to 70% coupling efficiency were demonstrated.
• The coupler design exhibits polarization independence for both TE and TM modes.
• Key design parameters influencing performance were identified.

Conclusions:

• SiON-based grating-assisted codirectional couplers are effective for dissimilar waveguides.
• The proposed design enables efficient, polarization-independent vertical light coupling.
• This technology has potential applications in integrated photonic devices.