Panda-type few-mode fiber-enabled microwave photonic filter with a reconfigurable finite impulse response

Leveraging various physical dimensions of optical signals allows significant scaling of the transmission capacity for optical communications. Here we experimentally demonstrate a reconfigurable microwave photonic filter (MPF) enabled by both mode and polarization division multiplexing arising in a Panda-type few-mode fiber. The LP₀₁, LP₀₁, LP₁₁, and LP₁₁ modes are used to realize optical true-time delay lines of the MPF, thus achieving a four-tap finite impulse response (FIR) with a free spectral range of around 2.22 GHz. Due to the employed delay between two orthogonal polarizations, the number of taps arising in its FIR can be doubled. Moreover, the reconfigurable FIR of the MPF can be achieved by loading the corresponding phase pattern onto a spatial light modulator. Finally, the low-pass FIR can be switched to the bandpass FIR due to the introduction of polarization modulation, indicating the flexible manipulation of the FIR for the multi-dimensional division multiplexing enabled MPF.