Low-voltage, high speed, compact silicon modulator for BPSK modulation.

A low voltage, high speed, compact silicon Mach-Zehnder Interferometer (MZI) modulator for Binary Phase Shift Keying (BPSK) modulation has been demonstrated. High modulation efficiency, VπLπ equals to 0.45V·cm, was obtained in a 1mm length device owing to a higher doping concentration and low-loss traveling-wave electrode. 25 Gb/s non-return-to-zero(NRZ)-BPSK with 6Vpp RF driving signal was achieved. Driven by a very low 3Vpp RF signal, the 10 Gb/s NRZ-BPSK was also realized benefiting from the high modulation efficiency and the low-voltage driving scheme. The power consumption for the BPSK modulation was as low as 0.118 W. These results prove that the silicon modulator is suitable for advanced communication system with low power consumption.

Demonstration of low power penalty of silicon Mach-Zehnder modulator in long-haul transmission.

We demonstrate error-free 80km transmission by a silicon carrier-depletion Mach-Zehnder modulator at 10Gbps and the power penalty is as low as 1.15dB. The devices were evaluated through the bit-error-rate characterizations under the system-level analysis. The silicon Mach-Zehnder modulator was also analyzed comparatively with a lithium niobate Mach-Zehnder modulator in back-to-back transmission and long-haul transmission, respectively, and verified the negative chirp parameter of the silicon modulator through the experiment. The result of low power penalty indicates a practical application for the silicon modulator in the middle- or long-distance transmission systems.

Wavelength demultiplexing structure based on arrayed plasmonic slot cavities.

A compact wavelength demultiplexing structure based on arrayed metal-insulator-metal (MIM) slot cavities is proposed and demonstrated numerically. The structure consists of a bus waveguide perpendicularly coupled with a series of slot cavities, each of which captures SPPs at the resonance frequency from the bus waveguide and tunes the transmission wavelength by changing its geometrical parameters. A cavity theory model is used to design the operating wavelengths of the structure. Moreover, single band transmission of each channel and the adjustable transmission bandwidth can be obtained by altering the drop waveguide positions and the coupling distance. The proposed arrayed slot cavity-based structure could be utilized to develop ultracompact optical wavelength demultiplexing device for large-scale photonic integration.

Compact double-layer subwavelength binary blazed grating 1×4 splitter based on silicon-on-insulator.

We describe a compact double-layer waveguide grating splitter that not only achieves efficient coupling between single mode fiber and a silicon-on-insulator optical waveguide but also realizes effective splitting. By appropriate choice of waveguide/grating parameters, including thicknesses, periods, height, and fill factor to optimize the mode matching, coupling efficiency is improved and the value of power difference of each output port is also significantly decreased. The maximum of power difference between four output ports is about 6.2%; however, the minimum value is only 0.6% or so. Moreover, the average power difference of four output ports is lower than 10% for TE polarization light over the 10 nm wavelength bandwidth centered at 1.54 µm. In addition, the splitter structure has the best tolerance for grating fabrication with deviations of grating depth 90 nm.

Band-pass plasmonic slot filter with band selection and spectrally splitting capabilities.

An ultra-compact surface plasmon polaritons (SPPs) narrow band-pass filter based on a slot cavity is proposed and numerically investigated. Attributed to the coupled resonances in the cavity, the filter demonstrates pass-band selection capability. Also, by varying the positions of output waveguides, the filter shows the spectrally splitting function. Moreover, the combination of the adjustments to the length/width of the slot cavity and to the coupling distance provides more flexibility in design for the locations and widths of the pass-bands of the proposed filter.

Highly sensitive silicon microring sensor with sharp asymmetrical resonance.

We analyze the resonance spectrum in silicon microring resonators taking into account the end-facet reflection from a coupled waveguide, which can provide a dense set of Fabry-Perot resonances. Based on the simple configuration of a microring coupled with a waveguide, the resulting asymmetric Fano-like non-Lorentzian resonance is obtained by scattering theory and experiment. Enhanced sensing performance with steeper slope to the resonance is theoretically predicted and experimentally demonstrated for a 10-microm racetrack silicon microring resonator. A high sensitivity of approximately 10(-8) RIU in terms of the detection limit is obtained in a 30-dB signal-to-noise ratio (SNR) system.