Photonic Hilbert Transformer Employing On-Chip Photonic Crystal Nanocavity

We propose and experimentally demonstrate a photonic Hilbert transformer using an on-chip silicon photonic crystal nanocavity (PCN). We prove that a PCN can implement photonic Hilbert transformation after certain structure design. The PCN consists of a cavity of three-defect-long (L3) type with a lattice constant of a = 420 nm and a hole radius of r/a = 0.3. We demonstrate Hilbert transformations of input Gaussian pulses with different pulsewidth, and all the average deviations are less than 5.8%. The PCN has a small size of 10 μm × 10 μm, which maybe useful in high-density on-chip spectral shaper.