Chip-Scale Spectropolarimetric and Quantum Optical Phase Sensing with Semiconductor Nanostructures

When light interacts with materials, they selectively absorb or transmit specific colors (wavelengths) and polarizations, and can even change the light’s phase. These interactions, determined by the material’s properties and shape, reveal its composition, structure, and surface details, offering insights into its optical and further quantum photonic properties. However, measuring these light properties typically requires bulky equipment. This work focuses on integrating these measurement capabilities into a compact, chip-scale device for mobile optical sensing. We achieve this with a spectropolarimetric sensor using GaN elliptical nanopillar photodiodes. Precisely tuning the nanopillars’ dimensions allows us to control their UV-visible spectrum and polarization-dependent light absorption, enabling simultaneous reconstruction of spectral and polarization information from minimal data. Beyond classical sensing, we address quantum optical needs, which require high-precision phase detection of photon qubits. We present a GaAs-integrated photonic circuit designed to measure the nonlinear phase shifts that may occur when two photons interact with a quantum dot (QD). We also propose optically controllable, enhanced electron spin-spin interactions in GaN QDs, offering a path toward scalable quantum information hardware. This integrated semiconductor approach provides a practical route to advanced spectropolarimetric sensing and quantum optical phase detection, paving the way for next-generation photonic systems.

CHAIR:  Professor Pei-Cheng Ku