Phase-resolved all-fiber reflection-based s-NSOM for on-chip characterization

• Published in: Optics express Vol. 30; no. 23; pp. 41118 - 41132
• Main Authors: Sun, Yizhi, Yan, Xiaohong, Blaize, Sylvain, Bachelot, Renaud, Wei, Hong, Ding, Wei
• Format: Journal Article
• Language: English
• Published: 07-11-2022
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.475192

We report on a phase-resolved, reflection-based, scattering-type near-field scanning optical microscope technique with a convenient all-fiber configuration. Exploiting the flexible positioning of the near-field probe, our technique renders a heterodyne detection for phase measurement and point-to-point frequency-domain reflectometry for group index and loss measurement of waveguides on a chip. The important issue of mitigating the measurement errors due to environmental fluctuations along fiber-optic links has been addressed. We perform systematic measurements on different types of silicon waveguides which demonstrate the accuracy and precision of the technique. With a phase compensation approach on the basis of a common-path interferometer, the phase drift error is suppressed to ∼ 0.013°/s. In addition, characterizations of group index, group velocity dispersion, propagation loss, insertion loss, and return loss of component waveguides on a chip are all demonstrated. The measurement accuracy of the propagation loss of a ∼ 0.2 cm long nano-waveguide reaches ±1 dB/cm. Our convenient and versatile near-field characterization technique paves the way for in-detail study of complex photonic circuits on a chip.