Panda Type Few-Mode Fiber Capable of Both Mode Profile and Polarization Maintenance

We report the design, fabrication, and characterization of a panda type few-mode fiber (panda-FMF) capable of both mode profile and polarization maintenance, due to the use of two applied stress rods into the conventional FMF. The panda-FMF can support six spatial modes including LP
₀₁
, LP
_11a
, LP
_11b
, LP
_21a
, LP
_21b
, and LP
₀₂
, and each possesses two orthogonal linear polarization modes. According to the characterization results of panda-FMF, we theoretically identify that the effective refractive index difference between either two spatial or orthogonal linear polarization modes is more than 1 × 10
⁻⁴
over the C-band. Moreover, the experimental results verify that both mode profile and polarization of high-order radially asymmetric modes can be perfectly maintained even under severe twist rate of 1.57 rad/m.