Probing Hermite-Gaussian modes via single-slit truncation

Abstract

We present a method for probing the mode characteristics of Hermite-Gaussian (HG) beams by intentionally breaking mode orthogonality through spatial truncation. By applying an axially centered single-slit aperture via a spatial light modulator, we facilitate the coupling of higher-order HG modes into a single-mode fiber. We show analytically and experimentally that the resulting coupled power is highly sensitive to the mode order and beam waist parameters. Our results reveal that the number of observed power peaks scales as half the mode order (m/2), providing a direct metric for mode identification. Furthermore, we characterize the influence of beam waist mismatch and hologram scaling on the coupling efficiency. These findings offer a robust approach for validating structured light parameters using projective measurements.