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arXiv · 2605.04382

Fundamental Limitations of Terahertz Quarter-Wave Plates Based on High-Contrast Dielectric Gratings

Oleg Kameshkov·Rajour Tanyi Ako·Madhu Bhaskaran·Ilya Shadrivov
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Abstract

We present a systematic study of high-contrast dielectric gratings operating as broadband quarter-wave plates in the terahertz range. Using higher-order effective medium theory, we identify an achromatic operating regime characterized by a parabolic-like frequency dependence of the phase retardation. This framework reveals a fundamental bandwidth limit imposed by single-mode operation in one-dimensional rectangular gratings. We show that Fabry-Perot resonances and the higher-order modes set intrinsic constraints on achievable performance. The theoretical predictions are quantitatively validated by rigorous full-wave simulations and terahertz time-domain spectroscopy experiments. Our results reveal clear physical design rules and intrinsic performance limits for broadband terahertz dielectric grating waveplates.

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Oleg Kameshkov, Rajour Tanyi Ako, Madhu Bhaskaran, Ilya Shadrivov. 2026-05-06. Fundamental Limitations of Terahertz Quarter-Wave Plates Based on High-Contrast Dielectric Gratings. https://arxiv.org/abs/2605.04382

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