Tunable Bragg reflectors on silicon-on-insulator rib waveguides

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nanofabrication

Background:

• Silicon-on-insulator (SOI) waveguides are essential for integrated photonics.
• Bragg reflectors are critical components for wavelength selectivity in optical circuits.
• Efficient fabrication of high-performance Bragg reflectors on SOI platforms remains a challenge.

Purpose of the Study:

• To design, fabricate, and characterize novel Bragg reflectors on SOI rib waveguides.
• To investigate the impact of fabrication parameters on reflector performance.
• To explore the thermal tunability of the fabricated Bragg reflectors.

Main Methods:

• A double lithography process combining electron-beam lithography (for gratings) and photolithography (for waveguides).
• Detailed characterization of reflector performance, including reflectivity, bandwidth, and insertion loss.
• Analysis of the influence of etching depth and waveguide geometry on device performance.

Main Results:

• Achieved reflectivity greater than 80% over a 0.8 nm bandwidth.
• Demonstrated low insertion loss of only 0.5 dB.
• Observed a thermal tunability of 77 pm/K, indicating potential for active wavelength control.

Conclusions:

• The developed double lithography process enables the fabrication of high-performance, low-loss Bragg reflectors on SOI rib waveguides.
• The results highlight the significant influence of etching depth and waveguide geometry on reflector characteristics.
• The demonstrated thermal tunability opens avenues for dynamic wavelength tuning in photonic integrated circuits.