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Updated: Feb 14, 2026

Phase Contrast and Differential Interference Contrast DIC Microscopy
Published on: August 6, 2008
Demonstration of a thermo-optic phase shifter by utilizing high-Q resonance in high-index-contrast grating
Abstract:
A thermo-optic phase shifter is proposed and demonstrated by utilizing the high-Q resonance in high-index-contrast grating (HCG). The Q-factor up to ∼12000 is measured in a footprint of 110 μm×300 μm. By heating the HCG with paired metal strip micro-heaters, the optical resonance shifts, which induces phase modulation. A phase shift of ∼1.2π under heating power of ∼32 mW is directly observed and demodulated from the fringes shifting in a Michelson interferometer. The proposed configuration can also be extended to realize high-speed phase shift by adopting electro-optical modulation.
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