A simple and low-crosstalk 1 × 4 silicon mode (de)multiplexer based on multimode grating-assisted-couplers is proposed. Mode transitions can be flexibly controlled by designing the grating period at the phase-matching condition. Due to the contra-directional coupling, precise control of the coupling strength and the coupling length are not needed in the system. Calculation results show that the insertion loss and the 3 dB bandwidths of the device are 0.2 dB and 3.7 nm, 0.34 dB and 7.6 nm, and 0.21 dB and 11.8 nm for the channels which (de)multiplex to the 1st, 2nd, and 3rd modes of the bus waveguide, respectively.

Giant enhancement of H2S gas response by decorating n-type SnO2 nanowires with p-type NiO nanoparticles Appl. Phys. Lett. 101, 253106 (2012) The role of Euler buckling instability in the fabrication of nanoelectromechanical systems on the basis of GaAs/AlGaAs heterostructures Appl.

We design and fabricate a wavelength-selective nonblocking 4 × 4 silicon optical router based on microring resonator for use in future integrated photonic interconnection networks. We successfully demonstrate 12 possible I/O routing paths and present 13 nonblocking operating states, including four broadcasting states, with worst-case extinction ratio and cross talk of 21.05 and -21.56 dB, respectively. Thermal tuning is employed to compensate the resonance shift of microring resonators caused by fabrication errors and adjust the resonance to match the International Telecommunication Unit grid with the channel spacing of 100 GHz.

A lateral-apodized add-drop filter is demonstrated in a multimode asymmetric waveguide Bragg grating. This design utilizes two individual superposed gratings with the same sidewall corrugation depth. The strong side lobes of the grating filter are efficiently suppressed by mapping the target apodization profile into lateral shifts between the periods of the two gratings. Compared with other apodized technology, this device is easier to be realized. Experimental results show that the side-lobes suppression ratio can reach 18.5 dB, and a bandwidth of 9.5 nm is achieved by a large corrugation width of 150 nm. The insertion loss at the drop port is only 0.8 dB, and the extinction ratio is up to 24 dB at the through port.

Compact polarization beam splitter (PBS) based on grating-assisted couplers is proposed by utilizing contra-directional coupling between two corrugated strip waveguides. The co-directional coupling in the device is greatly suppressed by the designed asymmetric structure. The phase matching condition is only satisfied for TE polarization at the central wavelength of 1550 nm by a spatially periodic refractive-index perturbation. Due to the contra-directional coupling, the device breaks the limit of the precise control of the coupling strength and length. The simulation results show that the presented PBS, with a coupling length of only 19 μm, has a broad working bandwidth (∼40  nm) for a crosstalk below -12  dB. A large fabrication tolerance (±40  nm) for the waveguide width is also achieved.