Comment to "Nonreciprocal Light Propagation in a Silicon Photonic Circuit"

TL;DR

This comment critiques a previous paper on nonreciprocal light propagation, clarifying that its interpretation conflicts with fundamental reciprocity principles and referencing prior work on the device concept.

Contribution

It clarifies the incorrect interpretation of nonreciprocity in the original paper and emphasizes the importance of fundamental reciprocity theorems.

Findings

The original interpretation is inconsistent with Lorentz reciprocity.

The device concept was previously introduced in earlier work.

The critique emphasizes correct theoretical understanding.

Abstract

In the article "Nonreciprocal Light Propagation in a Silicon Photonic Circuit" (Science 333, 729-733 (2011) a nonreciprocal waveguide system based on a combination of silicon, dielectrics and metals is reported. In this Comment it is explained that the interpretation with respect to nonreciprocity in this paper is incorrect and conflicts with the fundamental Lorentz reciprocity theorem. It is further pointed out that a previous publication already introduced the device concept.