High Q factor InP photonic crystal nanobeam cavities on silicon wire waveguides.

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Indium phosphide (InP)-based 1D photonic crystal nanobeam cavities are crucial for integrated optics.
• Achieving high-quality (Q) factors is essential for advanced photonic devices.
• Silicon on insulator (SOI) platforms offer a robust base for photonic integration.

Purpose of the Study:

• To fabricate and characterize high-Q InP-based photonic crystal nanobeam cavities on SOI waveguides.
• To investigate the impact of evanescent wave coupling on cavity Q factor.
• To understand the relationship between coupling strength and Q factor reduction.

Main Methods:

• Fabrication of InP-based 1D photonic crystal nanobeam cavities using optimized processes.
• Encapsulation of nanocavities to enhance Q factor.
• Experimental and numerical analysis of evanescent wave coupling effects.
• Measurement of Q factor and electromagnetic field distribution.

Main Results:

• Demonstrated intrinsic Q factors exceeding 100,000 for fully encapsulated InP nanocavities.
• Quantified the reduction in Q factor due to evanescent wave coupling.
• Observed up to a factor of 4 reduction in intrinsic Q factor.
• Correlated coupling strength with modifications in resonant mode electromagnetic field distribution.

Conclusions:

• High-Q InP photonic crystal cavities can be successfully fabricated on SOI waveguides.
• Evanescent wave coupling is a critical factor limiting the achievable Q factor in such devices.
• Understanding and controlling coupling is vital for optimizing performance in integrated photonic systems.