Inter-layer light transition in hybrid III-V/Si waveguides integrated by µ-transfer printing.

We demonstrate low-loss and broadband light transition from III-V functional layers to a Si platform via two-stage adiabatic-crossing coupler waveguides. A 900-µm-long and 2.7-µm-thick III-V film waveguide consisting of a GaInAsP core and InP cladding layers is transferred onto an air-cladding Si photonic chip by the µ-transfer printing (µ-TP) method.

Low-loss polysilicon subwavelength grating waveguides and narrowband Bragg reflectors in bulk CMOS.

The performance of a photonic functional device in bulk CMOS has been limited by the high propagation loss in polysilicon strip waveguide. Based on the zero-process-change methodology, we successfully reduce the propagation loss of polysilicon waveguide from 112 dB/cm to only 38 dB/cm by solely engineering the waveguide geometry for the first time. Low propagation loss is attributed to a significantly reduced optical overlap factor of 0.

Design of Wearable Headset with Steady State Visually Evoked Potential-Based Brain Computer Interface.

Brain-computer interface (BCI) is a system that allows people to communicate directly with external machines via recognizing brain activities without manual operation. However, for most current BCI systems, conventional electroencephalography (EEG) machines and computers are usually required to acquire EEG signal and translate them into control commands, respectively. The sizes of the above machines are usually large, and this increases the limitation for daily applications.

Mode-evolution-based silicon-on-insulator 3 dB coupler using fast quasiadiabatic dynamics.

We report a 2×2 broadband and fabrication tolerant mode-evolution-based 3 dB coupler based on silicon-on-insulator rib waveguides. The operating principle of the coupler is based on the adiabatic evolution of local eigenmodes. The key element of the device is an adiabatically tapered mode evolution region, which converts two dissimilar waveguides into two identical waveguides.

Narrowband silicon waveguide Bragg reflector achieved by highly ordered graphene oxide gratings.

Graphene oxide (GO) ultrathin film can be wafer-scale deposited by spin coating, can be patterned by laser interference lithography and oxygen plasma etching, can be thinned atomically (0.26 nm/min) and oxidized by ozone treatment, and is a relatively transparent and low-refractive-index material compared to pristine graphene. All those unique properties prompt us to realize a low-loss (∼5  dB/cm), high-extinction-ratio (19 dB), and narrowband (0.