Single-polarization large-mode-area fibre at 1030nm and 1550nm

Summary form only given. High-power fibre laser systems generally rely on microstructured fibres combining an effective single-mode emission and a very large-mode area (V-LMA, D _core > 50μm). Most of time, the targeted applications (one can cite for instance the frequency conversion [1]) require a crucial control of the state of polarization (SOP) of the emitted beam, leading to the development of polarization-maintaining (PM) or single-polarization (PZ) fibres owing to the use of stress applying parts (SAP) [2, 3]. The current study has been focusing on judiciously introducing SAP into VLMA fibres to control the SOP of the fundamental mode (FM). Fully-aperiodic large-pitch fibres (FA-LPF) which have proved their potential to delocalize efficiently the HOM out of the gain region [4] are used here as basic concept. First, a numerical approach has been led consisting in adding SAP in the fibre structure in order to obtain enough birefringence while maintaining the effective single-mode operation. A single-polarization is then obtained due to a selective modal coupling of one SOP of the FM with a cladding HOM as shown on Fig. 1(a-d). In a second time, the designed fibre has been fabricated. Several samples have been drawn with core diameter from 40μm to 140μm.