Kecheng Yang

Piezoelectric tuning of narrowband perfect plasmonic absorbers via an optomechanic cavity.

Optical antennas enable the control of light-matter interaction on the nanometer scale. Efficient on-chip electrical switching of plasmonic resonances is a crucial step toward the integration of optical antennas into practical optoelectronic circuits. We propose and numerically investigate the on-chip low-voltage linear electrical tuning of a narrowband optical antenna perfect absorber via a piezoelectric optomechanic cavity. Near unity absorption is realized by an array of gold nanostrip antennas separated from a membrane-based deformable backreflector by a small gap. A narrow linewidth of 33xa0nm at 2.58xa0μm is realized through the coupling between the plasmonic mode and photonic mode in the cavity-enhanced antenna structure. An aluminum nitride piezoelectric layer enabled efficient actuation of the backreflector and therefore changed the gap size, allowing for the tuning of the spectral absorption. The peak wavelength can be shifted linearly by 250xa0nm with 10xa0V of tuning voltage, and the tuning range is not limited by the pull-in effect. The polarization dependence of the nanostrip antenna coupled with the optomechanic cavity allows the use of our device as a voltage tunable polarization control device.

Novel 64×2.5 Gb/s all-optical OFDM symbol generator based on triangle waveform driving-LiNbO3 modulators

We propose a novel and simple all-optical 160-Gb/s orthogonal frequency division multiplexing (OFDM) symbol generator which is based on discrete triangle waveform driving-LiNbO3 modulators to realize largerange linear optical shift. The entire system needs 64 discrete modulators: at the transmitter, a 2.5-Gb/s optical duobinary (ODB) modulator for data modulation and a 2.5-Gb/s triangle waveform driving-LiNbO3 phase modulator for phase shift to generate each subcarrier; and at the receiver, a 2.5-GHz optical band pass filter (OBPF) using Faraday anomalous dispersion optical effect to separate them. Excellent bit error rate (BER) is observed after 1060 km of transmission without any dispersion compensation.

Nanoantenna Integrated Thermomechanical Infrared Detector

We numerically studied the nanoantenna integrated thermomechanical mid-infrared detector working at room temperature based on bi-material structures. Three separate bilayer configurations are investigated and optimized for maximum thermomechanical deflection. The integrated optical nanoantennas are geometrically tuned to reach the highest optical absorption at 6xa0μm. Thermal time constants and fundamental noise equivalent powers of the three bilayer configurations are also calculated. We also discuss the potential implementation of our detector in infrared polarimetry.

Investigations on combined XPM and FWM effects on optical pulse propagation in dynamic IP traffic over WDM networks

The influence of IP bursty traffic on combined nonlinear effects of XPM (cross phase modulation) and FWM (four-wave mixing) in IP over WDM networks are investigated and calculated by solving the nonlinear Schrodinger equation (NLSE) using a novel method under two conditions: on–off Poisson distributed IP traffic and self-similar traffic. Different eye diagrams are obtained under various IP traffic types and input optical powers. When the input power of a single channel is larger than 3 dBm, the effect of IP bursty traffic will deteriorate eye diagrams dramatically in a 40-channel WDM network. We also calculate the FWM powers and interchannel power distribution under different IP traffic loads. Based on the interchannel power distribution, we could find out which channels affect the probe channel seriously by the FWM effect. All these numerical results are useful for the Quality-of-Service (QoS) design, traffic grooming, lightpath routing, and wavelength assignment of IP over WDM networks.

Nanoantenna integrated infrared pixels

We investigated a nanoantenna integrated thermomechanical infrared pixel based on bi-material nanobeam. Three bilayer configurations are numerically studied and optimized towards maximum thermomechanical deflection. The integrated optical nanoantennae are geometrically tuned to reach the highest optical absorption at 6 μm. Thermal time constants and fundamental noise equivalent powers of the three bilayer configurations are also calculated. We also discuss the potential implementation of our detector as an infrared polarimetric sensor.