Lee Crudgington

Multipurpose silicon photonics signal processor core

Integrated photonics changes the scaling laws of information and communication systems offering architectural choices that combine photonics with electronics to optimize performance, power, footprint, and cost. Application-specific photonic integrated circuits, where particular circuits/chips are designed to optimally perform particular functionalities, require a considerable number of design and fabrication iterations leading to long development times. A different approach inspired by electronic Field Programmable Gate Arrays is the programmable photonic processor, where a common hardware implemented by a two-dimensional photonic waveguide mesh realizes different functionalities through programming. Here, we report the demonstration of such reconfigurable waveguide mesh in silicon. We demonstrate over 20 different functionalities with a simple seven hexagonal cell structure, which can be applied to different fields including communications, chemical and biomedical sensing, signal processing, multiprocessor networks, and quantum information systems. Our work is an important step toward this paradigm.Integrated optical circuits today are typically designed for a few special functionalities and require complex design and development procedures. Here, the authors demonstrate a reconfigurable but simple silicon waveguide mesh with different functionalities.

Dual-etch apodised grating couplers for efficient fibre-chip coupling near 1310 nm wavelength

We present our recent work on fibre-chip grating couplers operating around 1310 nm. For the first time, we demonstrate the combination of dual-etch and apodization design approaches which may achieve a coupling efficiency of 85% (-0.7 dB). Subwavelength structures were employed to modify the coupling strength of the grating. -1.9 dB efficiency was measured from a first set of fabricated structures.

Ultrafast perturbation maps as a quantitative tool for testing of multi-port photonic devices

Advanced photonic probing techniques are of great importance for the development of non-contact wafer-scale testing of photonic chips. Ultrafast photomodulation has been identified as a powerful new tool capable of remotely mapping photonic devices through a scanning perturbation. Here, we develop photomodulation maps into a quantitative technique through a general and rigorous method based on Lorentz reciprocity that allows the prediction of transmittance perturbation maps for arbitrary linear photonic systems with great accuracy and minimal computational cost. Excellent agreement is obtained between predicted and experimental maps of various optical multimode-interference devices, thereby allowing direct comparison of a device under test with a physical model of an ideal design structure. In addition to constituting a promising route for optical testing in photonics manufacturing, ultrafast perturbation mapping may be used for design optimization of photonic structures with reconfigurable functionalities.Advanced photonic probes are important for the development of non-contact wafer-scale testing of photonic chips. Here, Vynck et al. develop a quantitative technique based on mapping of transmittance variations by ultrafast perturbations to analyze arbitrary linear multi-port photonic devices.

Integrated RF-photonic delay lines using reconfigurable photonic waveguide meshes

In this paper we demonstrate the implementation of optical delay lines on a programmable hexagonal waveguide mesh integrated in Silicon on Insulator (SOI). This building block enables the synthesis of reconfigurable discrete-time filters and beamforming networks.

Compact programmable RF-photonic filters using integrated waveguide mesh processors

Integrated waveguide meshes have been recently proposed as an advanced technical solution for the implementation of universal processors. In this paper we investigate their potential for the implementation of simple and cascaded programmable RF-photonic filters. We specifically address the case of single sideband and carrier injection filters and the possibility of implementing parallel filtering schemes. We demonstrate an extensive amount of device flexibility including: circuit design topology, filter tunability and reconfigurability. The device composed of 7-cells allows the synthesis of basic photonic circuits and more complex cascaded combinations of ring resonators and Mach-Zehnder interferometers.

Author Correction: Multipurpose silicon photonics signal processor core

Change History: A correction to this article has been published and is linked from the HTML version of this article.

Improving the efficiency of fibre-chip grating couplers near 1310 nm

We present our recent work on fibre-chip grating couplers operating around 1310 nm. For the first time, we demonstrated the combination of dual-etch and apodization design approaches which can offer state of the art performance. Initial tests from fabricated structures show a -2.2dB loss.

Dataset for "Development of Amorphous Silicon Solar Cells with Plasmonic Light Scattering"

Dataset supporting: Crudgington, Lee, Rahman, Tasmiat and Boden, Stuart (2016) Development of Amorphous Silicon Solar Cells with Plasmonic Light Scattering. Journal of Vacuum Science and Technology B Microelectronics and Nanometer Structures.This paper reports the result of simulation and fabrication of the optical effects of metallic nano-particle arrays within amorphous silicon thin-films. A finite-difference time domain approach is used to design and model nano-particle arrays within opto-electronic models of thin-film amorphous silicon. An increase in optical scattering is observed, resulting in an increase in power absorption within the material active region and a reduction in optical reflection from the film surface. It is shown that this enhancement in optical performance depends on the particle size, shape, position within the structure and proximity to the metallic back reflector. Process development of metal-island films on silicon and glass, followed by the fabrication and measurement of amorphous silicon P-I-N devices featuring plasmonic nano-particles is demonstrated; showing an enhancement in-keeping with results achieved using simulation.