Widely Tunable Photonic Filter Based on Equivalent Chirped Four-Phase-Shifted Sampled Bragg Gratings

Area of Science:

• Photonics
• Integrated Optics
• Semiconductor Devices

Background:

• Photonic filters are crucial for wavelength-selective optical signal processing.
• Achieving tunable dual-band operation in a single device presents a significant challenge.
• Silicon photonics offers a promising platform for integrated optical devices due to its strong thermo-optic effect.

Purpose of the Study:

• To design and demonstrate an integrated dual-band photonic filter on a silicon-on-insulator platform.
• To achieve tunable optical frequency division using the thermo-optic effect.
• To explore the performance of the filter for different frequency division setups.

Main Methods:

• Utilized equivalent chirped four-phase-shifted sidewall-sampled Bragg gratings (4PS-SBG) with two π-phase shifts.
• Employed the reconstruction equivalent-chirp technique for grating design.
• Integrated microheaters (MHs) for thermo-optic tuning of the photonic filter.
• Tested the device with a 100 GHz semiconductor passive mode-locked laser.

Main Results:

• Successfully demonstrated an integrated dual-band photonic filter with two passbands.
• Achieved continuous and wide-range optical frequency division by tuning microheaters (0-85 mA).
• Adjustable frequency interval between passbands ranged from 52.1 to 439.5 GHz.
• Showcased four frequency division setups at 100, 200, 300, and 400 GHz.

Conclusions:

• The developed photonic filter effectively enables dual-band operation and tunable optical frequency division.
• The silicon-on-insulator platform and integrated microheaters provide a robust solution for dynamic control.
• This technology holds potential for advanced optical communication and signal processing systems.