već ne znam kako ćete se snaći. Možda će neko od kolega znati/pronaći prave termine na hrvatskom.
bound mode
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bound mode: In an optical fiber, a mode that (a) has a field intensity that decays monotonically in the transverse direction everywhere external to the core and (b) does not lose power to radiation. Note: Except for single-mode fibers, the power in bound modes is predominantly contained in the core of the fiber. (188) [After 2196] Synonyms guided mode, trapped mode.
http://www.its.bldrdoc.gov/fs-1037/dir-005/_0696.htm