For conclusion caps with the same diameter to that with the fiber, a bigger cored fiber, ordinarily “coreless” or “graded index” fiber is spliced to solitary mode or multimode transmitting/acquire fiber. The 1st generation of hollow-core optical fiber relies about the photonic band result photonic crystal hollow-core optical fiber; it https://directory4web.com/listings13096714/helping-the-others-realize-the-advantages-of-multicore-fiber-fusion-splicing