Institutional issuer: Thorlabs. This teaching insight appears in the Insights into Optical Fiber section of a product page; no personal author is identified.
The inspected indexed section labels 20 January 2020 as its last-edit date. That date belongs to the insight, not to the product's introduction.
Cited passages: Search-index full extracted section When does NA provide agood estimate of the fiber's acceptance angle?; GeometryDefines the Relationship; Single Mode Fibers are Different; Date of Last Edit: Jan. 20, 2020.