The transit times of photons traveling through opaque barriers such as dielectric stacks exhibit the Hartman saturation effect. This saturation of the transit time is quite sensitive to the addition of a single dielectric layers, even onto an already thick stack. These traversal times can vary significantly from sub-luminal to apparently super-luminal and vice versa with the addition of just a single layer to a 30 layer stack. We measure the photon traversal time through dielectric layer stacks with alternating refractive indices using a Hong-Ou-Mandel interferometer and observe transit time changes, both positive and negative, five times larger than the transit time through such a layer in isolation.
Citation: Optics Express
Pub Type: Journals
Hartman effect, Hong-Ou-Mandel, parametric downconversion, single photon, time delay