Francesco Dell’Olio

Theoretical investigation of indium phosphide buried ring resonators for new angular velocity sensors

Abstract. Here, we report the guidelines to be followed to optimize the design of a new angular velocity sensor based on an indium phosphide (InP) ring resonator. Optical properties of InP ring resonators have been investigated together with some significant physical effects for improving the sensor sensitivity. Three-dimensional algorithms have been utilized for the theoretical estimation of the waveguide loss. An optimized waveguide with propagation loss <0.3  dB/cm and a ring resonator with a quality factor of 1.5×106 have been designed. Performance of angular velocity sensors based on InP low-loss ring resonators has been estimated and discussed. Resolution of 10  deg/h and bias drift in the range of 0.1 to 0.3  deg/h have been evaluated for a fully integrated optical gyro including an InGaAsP/InP optical cavity having a footprint less than 24  cm2.

Micro-racetrack coupled-resonator optical waveguides in silicon photonic wires

Coupled-resonator optical waveguide (CROW) structures including coupled micro-racetrack resonators realized using silicon photonic wires are theoretically investigated in this paper. An accurate modelling procedure has been developed. It takes into account the differences in optical coupling between two identical resonators and between a straight waveguide (bus waveguide) and a resonator. The modelling approach is based on a mixed, very general procedure, based on the transfer matrix approach for CROW investigation, coupled mode theory in a generalized form for characterization of coupling between adjacent resonators and between bus waveguides and resonators and the full-vectorial finite element method for performing coupling coefficient calculation and waveguides modal analysis. This technique can be adopted to model a wide spectrum of different CROW structures. As an explicative example, CROW structures including three coupled micro-racetrack resonators have been investigated. A large quality factor (~7 × 105) has been predicted for a proposed CROW structure when the quasi-TE mode is excited. The influence of fabrication tolerances on CROW structures has been also investigated.

Effect of fabrication tolerances on the performance of two-dimensional polymer photonic crystal channel drop filters: a theoretical investigation based on the finite element method

Abstract. Guidelines for the design and fabrication of polymer photonic crystal channel drop filters for coarse wavelength division multiplexing are provided. A Fabry-Perot cavity consisting of a membrane-type slab photonic crystal, where a hole row perpendicular to the propagation direction is removed, is considered. We selected nanoimprinting as the manufacturing technique. The influence on the cavity performance of several key parameters, i.e., polymer core material, lattice geometry, defect length, and holes’ radius, has been investigated in a device compliant with the requirement of the ITU-T G.694.2 standard. A detailed analysis of the fabrication tolerances has been carried out at 1551 nm. The maximum acceptable drift of the geometrical parameters has been accurately evaluated by using the finite element method to prove that the fabrication tolerances do not significantly affect the performance of polymer filters for coarse wavelength division multiplexing, when manufactured by thermal nanoimprinting lithography.

Ultra-high Q/V hybrid cavity for strong light-matter interaction

The ability to confine light at the nanoscale continues to excite the research community, with the ratio between quality factor Q and volume V, i.e., the Q/V ratio, being the key figure of merit. In order to achieve strong light-matter interaction, however, it is important to confine a lot of energy in the resonant cavity mode. Here, we demonstrate a novel cavity design that combines a photonic crystal nanobeam cavity with a plasmonic bowtie antenna. The nanobeam cavity is optimised for a good match with the antenna and provides a Q of 1700 and a transmission of 90%. Combined with the bowtie, the hybrid photonic-plasmonic cavity achieves a Q of 800 and a transmission of 20%, both of which remarkable achievements for a hybrid cavity. The ultra-high Q/V of the hybrid cavity is of order of 106 (λ/n)−3, which is comparable to the state-of-the-art of photonic resonant cavities. Based on the high Q/V and the high transmission, we demonstrate the strong efficiency of the hybrid cavity as a nanotweezer for optica...

Innovative Integrated-Optic Resonator for Angular Rate Sensing: Design and Experimental Characterization

In this paper we report on the design, fabrication and characterization of an integrated-optic spiral resonator for angular rate sensing applications. The spiral resonator design has been optimized through a parametric analysis and a minimum angular velocity of about 10°/h, suitable for aerospace applications, has been theoretically predicted. The resonator has been fabricated in silica-on-silicon technology and characterized. Experimental results are in good agreement with the theoretical predictions.

Design of an ultra-compact graphene-based integrated microphotonic tunable delay line

The design of a continuously tunable optical delay line based on a compact graphene-based silicon Bragg grating is reported. High performance, in terms of electro-optical switching time (tswitch < 8 ns), delay range (Δτ = 200 ps), and figure of merit FOM = Δτ/A = 1.54x105 ps/mm2, has been achieved with an ultra-compact device footprint (A ~1.3 x 10-3 mm2), so improving the state-of-the-art of integrated optical delay lines. A continuous and complete tunability of the delay time can be achieved with a very low delay loss ( = 0.03 dB/ps) and a weak power consumption ( = 0.05 mW/ps). A flat bandwidth B = 1.19 GHz has been calculated by exploiting the slow-light effect in the device. This performance makes the proposed optical delay line suitable for several applications in Microwave Photonics (MWP), such as beamsteering/beamforming, for which large delay range, flat and wide bandwidth and small volume are required.