Design and Optimization of Polarization Splitting and Rotating Devices in Silicon-on-Insulator Technology

We review polarization splitting and rotating photonic devices based on silicon-on-insulator technology platform, focusing on their performance and design criteria. In addition, we present a theoretical investigation and optimization of some rotator and splitter architectures to be employed for polarization diversity circuits. In this context, fabrication tolerances and their influences on device performance are theoretically estimated by rigorous simulations too

Silicon Photonic Waveguides and Devices for Near- and Mid-IR Applications

Silicon photonics has been a very buoyant research field in the last several years mainly because of its potential for telecom and datacom applications. However, prospects of using silicon photonics for sensing in the mid-IR have also attracted interest lately. In this paper, we present our recent results on waveguide-based devices for near- and mid-infrared applications. The silicon-on-insulator platform can be used for wavelengths up to 4 μm; therefore, different solutions are needed for longer wavelengths. We show results on passive Si devices such as couplers, filters, and multiplexers, particularly for extended wavelength regions and finally present integration of photonics and electronics integrated circuits for high-speed applications

Picosecond optically reconfigurable filters exploiting full free spectral range tuning of single ring and Vernier effect resonators

We demonstrate that phase shifts larger than 2 pi can be induced by all-optical tuning in silicon waveguides of a few micrometers in length. By generating high concentrations of free carriers in the silicon employing absorption of ultrashort, ultraviolet laser pulses, the refractive index of silicon can be drastically reduced. As a result, the resonance wavelength of optical resonators can be freely tuned over the full free spectral range. This allows for active integrated optic devices that can be switched with GHz frequencies into any desired state by all-optical means

Investigation of a Fiberoptic Device Based on a Long Period Grating in a Ring Resonator

A fiberoptic architecture based on a ring resonator (RR) including a typical long period grating (LPG) was investigated. The interactions between the fundamental core mode (LP01 or HE11) coupled to the RR and the cladding mode (LP08), excited into the cavity by means of the LPG, allow a peculiar spectral response characterized by two splitting resonances to be achieved. The new LPGRR architecture is investigated theoretically and a mathematical modelling based on the transfer matrix method (TMM) is proposed. The theoretical results are compared with the experiments measured by an open-loop LPG, while the performance of the relative LPGRR was estimated by a theoretical parametric analysis. Finally, an overview of the possible LPGRR sensing applications is provided by investigating the features of a strain sensor operating in different environmental conditions

Performance of SOI Bragg Grating Ring Resonator for Nonlinear Sensing Applications

In this paper, a spectroscopic sensor formed by a silicon-on-insulator waveguiding Bragg grating ring resonator working in linear and non-linear regime is proposed. In linear regime, the device shows a spectral response characterized by a photonic band gap (PBG). Very close to the band gap edges, the resonant structure exhibits split modes having a splitting magnitude equal to the PBG spectral extension, whose characteristics can be exploited to obtain a RI optical sensor almost insensitive to the fabrication tolerances and environmental perturbations. When the device operates in nonlinear regime, exactly in the spectral region showing the split resonant modes, the RI sensing performance is strongly improved with respect to the linear regime. This improvement, demonstrated by taking into account all the non-linear effects excited in the integrated silicon structure (i.e., Two Photon Absorption (TPA), TPA-induced Free Carrier Absorption, plasma dispersion, Self-Phase-Modulation and Cross-Phase-Modulation effects as induced by Kerr nonlinearity) as well as the deleterious thermal and stress effects, allows enhancing the performance of the RI split mode resonant sensors, while achieving good immunity to the fabrication tolerances and environmental perturbations. The improvement in terms of sensor resolution can be at least one order of magnitude, still without using optimal parameters