Showing papers by "Zhechao Wang published in 2009"

Ultracompact low-loss coupler between strip and slot waveguides

Abstract: We present both theoretical and experimental results of an ultracompact waveguide coupler that is capable of highly efficient coupling of light from strip waveguides to slot waveguides, and vice versa. By optimizing the geometrical parameters, it is possible to achieve extremely low-loss coupling. A coupling efficiency of 97% has been obtained experimentally while keeping the overall size down to the range below 10 μm. Further analysis shows that the proposed coupler has relatively high tolerance to fabrication errors and is wavelength insensitive.

Experimental demonstration of an ultracompact polarization beam splitter based on a bidirectional grating coupler

Abstract: A bidirectional grating serving both, as a polarization beam splitter and a vertical coupler for Silicon on Insulator nanophotonic circuits is fabricated and characterized. The measured coupling efficiency is as high as 43%. The demonstrated device has a large 3-dB bandwidth and a high extinction ratio between two orthogonal polarizations.

Bragg grating-assisted optical triplexer using two silicon nanowire-based directional couplers

Abstract: A triplexer based on silicon nanophotonic wire structure consisting of two Bragg grating-assisted directional couplers is proposed, which can multi/demultiplex three different wavelengths through a compact device. The device has low loss, low crosstalk, and a footprint of only 210 ×40 µm. The 1-dB bandwidth for the three channels located at 1310, 1490 and 1550 nm are 110, 20, and 20 nm, respectively.

Wavelength selective devices for WDM communication systems

Abstract: Depending on the application in optical communication systems different wavelength division multiplexing devices are used to increase network capacity by allowing several wavelength channels to be transmitted by one fiber, to add or drop different wavelength channels or to separate or put together channels carrying different services Depending on the application such devices can have wide, coarse or dense channel spacing Furthermore they can handle different number of channels In this paper we present some of such devices, their functionality, structures and fabrication technologies

Dielectric and plasmon slot waveguides for photonic integration

Abstract: Slot waveguides formed either in high-index dielectrics or in metals attract great interest because they provide sub-wavelength confinement in the slot region. While this feature is very attractive for devices relying on stimulated emission or nonlinear effects, it does not necessarily improve the integration density. The spacing between dielectric slot waveguides is still limited by diffraction. Although for metal (plasmon) waveguides the total field can be shrunk far beyond the diffraction limit, the associated increase in propagation loss will set practical limits on both the minimum waveguide width and edge-to-edge separation. Here we compare the packing densities for 3D slot waveguides in silicon and plasmon waveguides in gold with a silicon slot. As a reference we also consider silicon photonic wire. We calculate center-to-center waveguide separations (pitch) versus cross-talk level. We show that at ca 24 dB/µm cross-talk and requiring the attenuation length of at least 5 µm, plasmon slot waveguides can be packed ca 3.5 times denser than silicon slot waveguides, and ca 2.5 times denser than photonic wires. We also show examples of the fabricated devices.