Tunable Fano and EIT-like resonances based on two cascaded micro-ring resonators

Area of Science:

• Integrated photonics
• Optical devices
• Resonator physics

Background:

• Microring resonators (MRRs) are fundamental in integrated photonics.
• Conventional MRRs have symmetrical Lorentzian line shapes, limiting extinction ratio (ER) and slope rate (SR).
• Special transmission spectra (STS), like Fano and EIT-like resonances, offer asymmetric line shapes for improved performance.

Purpose of the Study:

• To overcome the limitations of symmetrical resonance line shapes in MRRs.
• To experimentally demonstrate a novel device capable of generating both Fano and EIT-like resonances.
• To achieve tunable STS for enhanced optical device applications.

Main Methods:

• Utilized two cascaded microring resonators (MRRs) with differing quality factors.
• Engineered the device on a silicon-on-insulator platform.
• Adjusted resonator wavelengths and phase shifter for wavelength tunability.

Main Results:

• Successfully generated both Fano and EIT-like resonances at distinct ports.
• Achieved a high ER of up to 31.2 dB and a sharp SR of 130.1 dB/nm for Fano resonance.
• Demonstrated tunable STS across desired wavelengths.

Conclusions:

• The novel cascaded MRR device effectively generates tunable Fano and EIT-like resonances.
• The device offers significantly improved ER and SR compared to conventional MRRs.
• Potential applications include optical sensors, slow/fast light generation, and microwave photonics.