Endlessly single-mode, broadband polarization-maintaining solid-core photonic crystal fiber

We present a polarization-maintaining photonic crystal fiber (PM-PCF), featuring a hybrid lattice structure that simultaneously achieves broadband single-mode guidance and enhanced birefringence through coordinated geometric and cross-optical-mode modulation. The fiber structure incorporates a hybrid triangular air-hole arrangement and a slightly elliptical core, effectively enhancing birefringence while enabling endlessly single-mode operation. Experimental results reveal a group birefringence of 5.6 × 10^-5 at 1550 nm, the suppression of polarization mode coupling with an <i>h</i>-parameter below 1.2 × 10^-4m^-1, and broadband single-mode operation across 600 to 1600 nm. This fiber combines high PM capability with broadband single-mode performance, offering potential applications in optical communication, high-power laser systems, and fiber optic sensing.