 Simin Feng

Simin Feng is the first-listed author, with Herbert G. Winful, of the 2001 primary paper Physical origin of the Gouy phase shift by Simin Feng and Herbert G. Winful. The full published byline supplies the name; the paper lists a University of Michigan affiliation and a Lucent Technologies present-address note. These identify the contribution at publication without inferring a present appointment or attaching an unverified namesake's portrait.^[ref]

The paper connects the Gouy phase with transverse confinement and the angular spectrum representation of a wave. Its analysis treats a finite beam as a superposition of plane waves with different transverse wave vector components and obtains the Gaussian phase contribution.^[ref]

An original one-coordinate example makes the localization issue quantitative. At a waist, let the field amplitude be $U(x)\propto e^{-x^2/w_0^2}$. Its Fourier transform has amplitude $\tilde{U}(k_x)\propto e^{-w_0^2{k}_x^2/4}$. Normalizing the squared magnitudes as distributions givesFor stipulated $w_0=100\mu \mathrm{m}$, the position spread is $50\mu \mathrm{m}$ and the transverse-wavenumber spread is $10^4{\mathrm{m}}^{-1}$. Halving the waist halves the first and doubles the second. The distributions here are constructed from field amplitudes; no single-photon counting experiment is assumed.

This Fourier localization of a Gaussian beam is part of the mathematics underlying the paper's focusing analysis. It also explains why a perfectly transverse-localized beam cannot retain the single propagation direction of an infinite plane wave. A field model, its phase convention and its transverse geometry must accompany any numerical phase claim.