Photonics Journal, IEEE - new TOC

Deterministic Synthesis of Optical Vortices in Tailored Plasmonic Archimedes Spiral

June 2013

We demonstrate that the shape and the orientation of a surface plasmon (SP) vortex can be deterministically tailored through the geometrical design of a plasmonic Archimedes spiral (PAS). Noncircular SP vortices exhibiting “c,” triangular, and square patterns are successfully synthesized under circular polarized plane-wave excitations. We provide clear evidence that the topological charges of the shaped SP vortices are dominated by the PAS under all geometrical settings. Our analytical description for the vortices shows excellent agreement with numerical simulations. Our design principle provides unique opportunity to manipulate nanoscale intensity and phase distribution of optical field on a flat area and may find interesting applications in plasmonic optical trapping and subwavelength patterning.

Similar Role of Transient Kerr Effect and Two-Photon Absorption in a Nonlinear Photonic Crystal Nanocavity

June 2013

The impacts of transient Kerr effect (TKE) on the characteristics of a nonlinear photonic crystal (PC) nanocavity are theoretically and numerically investigated. It is found that the features of TKE are very similar to those of two-photon absorption (TPA), but the mechanisms for them are essentially different. The relative magnitude of TKE to TPA is calculated, and the result indicates that the contribution of TKE should also be considered in actual designs of PC devices with Kerr nonlinearity. The theory presented in this paper will be helpful for the precise designs of nonlinear PC devices.

Scattering Loss Estimation Using 2-D Fourier Analysis and Modeling of Sidewall Roughness on Optical Waveguides

June 2013

We report an accurate scattering loss 3-D modeling technique of sidewall roughness of optical SOI waveguides based on Fourier and finite-difference time domain (FDTD) analysis methods. The Fourier analysis method is based on the image recovery technique used in magnetic resonant imaging. Losses for waveguides with isotropic and anisotropic roughness are calculated for wavelengths ranging from 1550 to 3800 nm and compared with reported results in literature. Our simulations show excellent agreement with published experimental results and provide an accurate prediction of roughness-induced loss of 3-D arbitrary shaped optical waveguides.

Microring-Based $N times N$ Scalable Polymeric Electrooptic Routing Switch Array: Theory, Architecture, and Design Scheme

June 2013

Device architecture and design scheme of an $N times N$ scalable electrooptic (EO) routing switch array (RSA) are proposed using electric-field-induced EO polymeric microrings. The basic 2 $times$ 2 /cross/bar EO switching element is optimized under 1550-nm wavelength, and the ring radius is only 13.76 $muhbox{m}$ with $< 10^{-4} hbox{dB/cm}$ bending loss. The basic element reveals a free spectral range (FSR) of 17 nm, a switching voltage of 5 V, and response times of 70/140 ps, and the crosstalk under cross and bar states are about $-$28.8 and $-$39.9 dB, respectively. Using 2 $times$ 2 switching elements, 4 $times$ 4, 8 $times$ 8, 16 $times$ 16, and 32 $times$ 32 RSAs are presented, under all routing paths, their maximum insertion losses are 2.57, 5.19, 5.99 and 7.59 dB, respectively, and their maximum crosstalk are $-$ 28.7, $-$28.7, $-$ 26.27 and $-$25.07 dB, respectively. Universal structure, routing scheme, electrical/optical responses, and dynamic power consumption (- C) of $N times N$ RSA are then demonstrated, and dependence relations between routing performances and the RSA size $N$ are achieved through data fitting. Comparisons with other reported passive/active routers/switches confirm that, due to superiority on fewer rings, picosecond faster response speed, zero static PC, and lower insertion loss and crosstalk, this polymer-based routing scheme can be a good candidate in on-chip optical systems.

Photonic-Assisted Ultrawideband Pulse Generator With Tunable Notch Filtering Based on Polarization-to-Intensity Conversion

June 2013

A photonic approach to generating ultrawideband (UWB) pulses with tunable band-rejection behavior and a chirp-free property, which is based on a nonlinear operated polarization-to-intensity converter, is proposed and demonstrated. As an initial phase shift of the incident light $varphi_{0} = pi$ , a high-order UWB pulse fully satisfied the indoor mask regulated by the Federal Communications Commission was synthesized by a pair of polarity-inverted and doublet-like pulses at the output port of the polarization beam combiner. Moreover, the notch band will occur dynamically on the power spectra of the UWB signals from 3 to 16 GHz through adjusting the relative delay time between both doublet-like pulses from 333 to 62.5 ps due to the effect of microwave photonic filtering, which means that the spectrum-overlay-induced interference between UWB and other narrow-band communication systems could be real-time averted. In addition, the polarity switch of the synthesized UWB pulse could be implemented by adjusting angle $alpha$ between the $x$-axis component of modulated light and the principal axis of the arm of transverse electric mode by the polarization controller.