Once a client is presented with the HSTS policy, it caches the information for the specified max-age period. During that period, the browser refuses to access the web service over unencrypted HTTP, and refuses to grant exceptions to certificate errors (if the site previously presented a valid, trusted certificate).
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term laser originated as an acronym for light amplification by stimulated emission of radiation.
When light traveling in the fiber core radiates into the fiber cladding, higher-order mode loss results. Together these factors limit the transmission distance of multimode fiber compared with single-mode fiber. Single-mode fiber is so small in diameter that rays of light can reflect internally through one layer only. Interfaces with single-mode optics use lasers as light sources. Lasers generate a single wavelength of light, which travels in a straight line through the single-mode fiber. Compared with multimode fiber, single-mode fiber has higher bandwidth and can carry signals for longer distances. Exceeding the maximum transmission distances can result in significant signal loss, which causes unreliable transmission. Attenuation and Dispersion in Fiber-Optic Cable