Mode field distribution and radiation loss in curved holey fibres

In communication lines holey fibres (HFs) can be exposed by bends. In the bend region the radiation loss can arise and influence the propagation properties of the HFs. Therefore, for better understanding HFs properties the behaviour of their modes in bend region has to be investigated. In this paper we analyse the distortion of the mode field distribution and radiation losses arising in HFs because of their bend with different guidance mechanisms. These fibres guide the light due to a central defect in the array using two different mechanisms: a photonic band gap effect or an effective index difference between the defect region, which forms the core, and remainder of the periodic region, which acts as the cladding.