Integrated waveguide Fabry-Perot microcavities with silicon/air Bragg mirrors.

Area of Science:

• Photonics and Optical Engineering
• Materials Science and Engineering
• Microfabrication Technologies

Background:

• Fabry-Perot cavities are crucial optical components for wavelength selection and filtering.
• Developing high-performance, tunable optical cavities is essential for advanced photonic integrated circuits.
• Silicon photonics offers a platform for miniaturized and scalable optical devices.

Purpose of the Study:

• To demonstrate in-plane microfabricated Fabry-Perot cavities with integrated silicon-on-insulator (SOI) rib waveguides.
• To investigate the performance of cavities utilizing cryogenically etched silicon/air distributed Bragg reflector (DBR) mirrors.
• To achieve thermo-optic tuning of the Fabry-Perot cavities.

Main Methods:

• Fabrication of in-plane Fabry-Perot cavities using SOI technology.
• Integration of cryogenically etched silicon/air DBR mirrors with rib waveguides.
• Characterization of cavity performance, including quality factor (Q), full width at half maximum (FWHM), finesse (F), free spectral range (FSR), and mirror reflectance (R).
• Demonstration of thermo-optic tuning using the integrated devices.

Main Results:

• Achieved a high quality factor (Q) of 26963.
• Measured a narrow full width at half maximum (FWHM) of 0.060 nm.
• Obtained a finesse (F) of 489 and a free spectral range (FSR) of 81.7 nm.
• Demonstrated high DBR mirror reflectance (R) of 99.4%.
• Successfully implemented thermo-optic tuning over a range of 6.7 nm.

Conclusions:

• The study successfully demonstrates high-performance in-plane microfabricated Fabry-Perot cavities on an SOI platform.
• The use of cryogenically etched silicon/air DBR mirrors provides excellent optical confinement and reflectance.
• The demonstrated thermo-optic tuning capability opens avenues for tunable photonic devices and integrated optical systems.