An ultra-compact integrated phase shifter via electrically tunable meta-waveguides.

Area of Science:

• Integrated photonics
• Metasurfaces
• Liquid crystal devices

Background:

• Thermal optical phase shifters (OPSs) are crucial for photonic integrated circuits but suffer from large size, high power consumption, and thermal crosstalk.
• Mach-Zehnder interferometers (MZIs) and micro-ring resonators (MRRs) are fundamental building blocks in photonic integrated circuits.

Purpose of the Study:

• To introduce a novel liquid crystal (LC) meta-waveguide phase shifter.
• To overcome the limitations of traditional thermal OPSs.
• To demonstrate the potential of LC meta-waveguides in accelerating neural network computations.

Main Methods:

• Embedding a Mie resonant metasurface into a waveguide.
• Utilizing liquid crystals to tune the phase of light propagation.
• Employing nanofabrication to create meta-waveguide integrated MZIs and MRRs.
• Applying voltage to modulate waveguide intensity.

Main Results:

• Achieved a novel integrated phase shifter based on LC meta-waveguides.
• Demonstrated voltage-controlled modulation of waveguide intensity.
• Highlighted advantages over thermal OPSs: small size (20 μm × 0.35 μm), no thermal crosstalk, low power consumption (<10 nW), and easy large-scale integration.
• Verified potential for accelerating neural network computation in a convolutional architecture.

Conclusions:

• The developed LC meta-waveguide phase shifter offers a promising alternative to thermal OPSs for advanced photonic integrated circuits.
• This technology has significant potential for energy-efficient and high-performance computing applications, including neural networks.