Novel photonic crystal fibre for low-noise coherent supercontinuum generation

We present a polarisation-maintaining all-normal dispersion photonic crystal fibre designed for 1030 nm femtosecond pumping, enabling ultra-stable and coherent supercontinuum (SC) generation spanning 650-1300 nm. The fibre's polarisation-maintaining properties are achieved through two larger central holes in the structure, which is an alternative approach to using conventional stress rods. The fibre is specifically engineered to achieve minimum dispersion near 1030 nm, making it ideal for ultrafast comb-based metrology, and widely tunable optical parametric amplifier (OPA) systems. We further investigate the influence of input pulse contrast on supercontinuum generation through both numerical simulations and experiments. Relative intensity noise (RIN) and phase noise (PN) are characterized using three complementary techniques: dispersive Fourier transform (DFT), the Bellini-Hänsch interferometric method, and the dual-reference oscillator cross-correlation technique. The results demonstrate excellent stability, with pulse-to-pulse RIN below 0.5%, an optical phase deviation under 15 mrad, and phase noise levels down to - 150 dBc/Hz at 10 kHz from the carrier, confirming the fibre's suitability for demanding ultrafast applications.