Close-spaced fused fibre wavelength division multiplexers with very low polarisation sensitivity

The authors describe the fabrication of high performance narrowband fused fibre wavelength multiplexers. A twisting technique is employed to reduce the polarisation sensitivity. Unlike other polarisation quenching methods, twisting maintains the intrinsically good temperature stability of the device. The twisting mechanism has been studied theoretically using a model with a realistic coupler cross-section.<>