Post-fabrication tuning of microring resonators using 3D-printed microfluidics

Area of Science:

• Photonics
• Microfluidics
• Materials Science

Background:

• Silicon microring resonators are key components in photonic integrated circuits.
• Tuning resonant frequencies is crucial for device functionality and applications.
• Existing tuning methods often require continuous energy input or complex fabrication.

Purpose of the Study:

• To demonstrate a novel method for tuning the resonant frequencies of silicon microring resonators.
• To utilize a 3D-printed microfluidic chip for precise control of resonator properties.
• To achieve tuning with zero energy consumption post-initialization.

Main Methods:

• Fabrication of a 3D-printed microfluidic chip.
• Overlaying the microfluidic chip directly onto a silicon microring resonator photonic circuit.
• Introducing aqueous solutions of varying sodium chloride (NaCl) concentrations.
• Monitoring resonant frequency shifts using optical measurements.

Main Results:

• A full free spectral range shift was observed at 10% NaCl concentration.
• A resonant wavelength shift of 1.514 nm was achieved for a 60 µm microring resonator.
• The demonstrated sensitivity was 89.05 nm/RIU for a cladding refractive index change of 0.017 RIU.

Conclusions:

• The 3D-printed microfluidic chip offers an effective, zero-energy-consumption method for tuning microring resonator frequencies.
• This technique provides a sensitive and scalable approach for optical sensor development and wavelength control.
• The demonstrated method holds promise for applications in tunable photonic devices and integrated optics.