luzi Lu

All-optical logic operation of polarized light signals in highly nonlinear silicon hybrid plasmonic microring resonators.

All-optical logic operation is theoretically demonstrated by means of polarization-dependent four-wave mixing (FWM) processes in a highly nonlinear silicon hybrid plasmonic waveguide (HPWG) microring resonator. We design an ultra-compact (radii = 1 μm) microring resonator (MRR) that is realized by using a silicon HPWG with the capacity for subwavelength-bending. The HPWG exhibits very high confinement (Aeff~0.045 μm(2)) that can result in a remarkably high nonlinear parameter (γ~3000 W(-1) m(-1)), given a highly nonlinear gap material. By manipulating the polarization properties of the pump and signals with a very low electric field (|E|~10(8) Vm(-1)), all-optical NOT, NOR, and NAND logical operations are obtained through the FWM process. These compact all-optical nanoplasmonic devices are stable, fabrication simplified, and silicon on insulator (SOI) compatible.

Inverse-designed single-step-etched colorless 3 dB couplers based on RIE-lag-insensitive PhC-like subwavelength structures

Inverse-designed free-form nanophotonic structures have shown great potential in designing ultra-compact integrated photonic devices, but strict fabrication requirements may hinder further applications. We propose here a photonic-crystal-like (PhC-like) subwavelength structure, which is insensitive to the lag effect that is the most common fabrication error. A colorless 3 dB coupler employing such a structure is designed, fabricated, and characterized. With only one-step etching, the coupling region of our final device occupies a compact footprint of 2.72×2.72  μm. The simulated insertion loss of each output port is about 3.2 dB over 100 nm bandwidth around 1550 nm, and the measured insertion losses of both ports are 3.35 dB, on average, over the observable 60 nm bandwidth with a near zero loss imbalance.

Inverse-designed ultra-compact star-crossings based on PhC-like subwavelength structures for optical intercross connect

Inverse-designed star-crossings with 8 and 10 ports are proposed, with ultra-short coupling lengths of 5.28μm and 5.4μm respectively. Their measured ILs are less than 1.6dB and 2.4dB respectively over 60nm bandwidth centered 1550nm wavelength.