Low-Stress High-Efficiency Local-Power Injection into Single- Mode Fibers

A novel practical technique which uses periodic small-scale microbends of a fiber's axis to inject high levels of single-mode power is introduced. This invention typically launches more than 20dB higher levels of power than those reported for commonly used macrobend injectors, while keeping fiber stresses below ordinary proof-test values, i.e. is equal to or less than 50kpsi. Advantages for splicing with this approach are: (1) Higher power allows scattered-light splice alignment to be used, which gives at least an order of magnitude improvement in sensitivity as compared to alignment using transmitted light, and (2) Low stress eliminates fiber breaks, which then allows unlimited injection times, thereby creating additional usages such as end-to-end testing.