Coupling characteristics of the spun optical fiber with multiple stress elements

摘要： Possible coupling between fundamental modes and higher order modes in a spun optical ?ber with multiple stress elements is analyzed. It shows that only the higher order HEmn mode with the opposite circular polarization state can be coupled with the fundamental HE11 mode. The coupling between the fundamental HE11 mode and the TE, TM or EH modes can never be occurred. In the possible coupling between HEmn mode and HE11 mode, m should be equal to N-1, where N is the number of the stress elements. As a comparison, the coupling property in a spun optical ?ber with single stress element is also demonstrated. In this case, the fundamental HE11 mode can not only be coupled with the higher orderHE2n mode but also can be coupled with the higher order TE mode.