Parallel emitted silicon nitride nanophotonic phased arrays for two-dimensional beam steering.

In this Letter, a two-dimensional (2D) beam steering on silicon nitride (SiNx) nanophotonic phased arrays from visible to near-infrared wavelengths is reported for the first time, to the best of our knowledge. In order to implement beam steering along the transverse direction for one-dimensional waveguide surface grating arrays, wavelengths from 650 to 980 nm provided by the supercontinuum laser are used to excite the phased array. Then the beams are parallel radiated with steering angles in a sequence of 26.

Liquid-cladded optical phased array for a single-wavelength beam steering.

We report a simple concept to implement a single-wavelength beam steering based on a liquid-cladded one-dimensional (1D) optical phased array (OPA). The beam steering was realized by modifying the waveguide mode effective index through replacing the liquid upper claddings. A prototype of a 32-channel liquid-cladded OPA was fabricated and characterized.

Broadband silicon nitride nanophotonic phased arrays for wide-angle beam steering.

In this Letter, the broadband operation in wavelengths from 520 nm to 980 nm is demonstrated on silicon nitride nanophotonic phased arrays. The widest beam steering angle of 65° on a silicon nitride phased array is achieved. The optical radiation efficiency of the main grating lobe in a broad wavelength range is measured and analyzed theoretically.

Ultra efficient silicon nitride grating coupler with bottom grating reflector.

We theoretically propose a silicon nitride (Si(3)N(4)) grating coupler (GC) with both ultrahigh efficiency and simplified fabrication processes. Instead of using a bottom distributed Bragg reflector (DBR) or metal reflector, a bottom Si grating reflector (GR) with comparable reflectivity is utilized to improve the coupling efficiency. The fully etched Si GR is designed based on an industrially standard silicon-on-insulator (SOI) wafer with 220 nm top Si layer.

Bandwidth improvement for germanium photodetector using wire bonding technology.

We demonstrate an ultrahigh speed germanium photodetector by introducing gold wires into the discrete ground electrodes with standard wire bonding technology. To engineer the parasitic parameter, the physical dimension of the gold wire used for wire bonding is specially designed with an inductance of about 450 pH. Simulation and experimental results show that the bandwidth of the photodetector can be effectively extended from less than 30 GHz to over 60 GHz.

Short and efficient mode-size converter designed by segmented-stepwise method.

We present an efficient segmented-stepwise method to design a short and low-loss mode-size converter. A silicon-on-insulator platform-based converter with 20 μm length and 95.2% conversion efficiency is acquired by taking only 10 optimization generations using 2D-FDTD method.

An SOI based polarization insensitive filter for all-optical clock recovery.

We fabricate and demonstrate a compact polarization insensitive filter for all-optical clock recovery (CR) based on silicon-on-insulator (SOI), which consists of a microring resonator (MRR) and two modified two-dimensional (2D) grating couplers. The distributed Bragg reflectors (DBRs) are introduced to improve the coupling efficiency of the 2D grating coupler. The MRR works as a comb filter for CR, while the 2D grating couplers serve as the polarization diversity unit to achieve a polarization insensitive operation.

[Reaction kinetics investigation of NVP in HPDLC gratings].

In order to get the HPDLC grating with high diffraction efficiency and perfect surface morphology, NVP was added into the reaction system of fabricating gratings and then the influence of NVP on the reaction kinetics of HPDLC was described. The analysis showed that NVP significantly increased the rate of polymerization in HPDLC photopolymerization, and as the highly cross-linked polymer network forms, the small mono-vinyl NVP appeared to react preferentially with double bonds inthe reaction system, facilitating additional conversion of pendant double bonds otherwise trapped in the polymer network. Furthermore, NVP also enhanced the degree of phase separation and got perfect surface morphology as well as higher refractive index modulation.