These devices are tested in a method that outputs a trace with a “dead zone” on the left and may include non-chromatography “ghost” peaks called OTDR. After applying APC or UPC polishing to flat parts of these devices, two of them may be linked with “matching gel.” These devices can be produced using meters-high draw towers. Splices can increase the attenuation coefficients of these devices, (-5[1])which are usually quoted in decibels per kilometer. (10[1]-5[1])Step index examples of the single-mode type of these (10[1])devices (10[2])have a typical value (10[1])around (10[1])0.1 (10[2])(“zero-point-one”) for the sine of the acceptance angle, which equals their numerical aperture. (10[1])Commercial examples of these devices typically achieve a bandwidth of a few gigabits (10[1])per second. (10[1])For 10 points, light in the core (-5[1])totally internally (10[1])reflects (10[2])off (10[1])the (10[1])cladding in what long, (10[3])thin (10[1])communication devices? (10[2])■END■ (10[1])