Double-cavity Fabry-Perot resonators based on one-dimensional silicon photonic crystals

This is the final version. Available from AIP Publishing via the DOI in this record.The 3rd Joint International Conference on Energy Engineering and Smart Materials (ICEESM-2018) and International Conference on Nanotechnology and Nanomaterials in Energy (ICNNE-2018)In this work we report on optical properties of Fabry-Pérot (FP) resonator based on Si-air one-dimensional photonic crystal (1D PC) with coupled double-cavity modes (or defects). These defects obtained by infiltration of the air-cavities of refractive index (nAir) with the filler of tunable refractive index. In the periodic structure of 1D PC, the filling of two defined grooves with a filler with a refractive index different from nAirleads to the appearance of two resonant modes, the position of which can be adjusted purposefully with changing of n filler. In comparison with (λ / 2) air resonators, the splitting of the doublet increases, which is explained by the increase in the coupling between the resonant modes due to the decrease in reflection R of the internal mirror. The coupled FP resonators design is CMOS compatible and has potential for application in tuning of individual transmission bands in wave-division multiplexing systems as well as for multiple narrow filters in the wide infrared spectral range.We acknowledge financial support from: The Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom via the EPSRC Grant No. EP/NO35569/1, and the Royal Society International Exchange Grant 2015/R3. The part of this research at the Ioffe Institute was supported by the Russian Federal Agency of Scientific Organizations

Multi-channel Si-liquid crystal filter with fine tuning capability of individual channels for compensation of fabrication tolerances.

This is the final version. Available on open access from Springer via the DOI in this record.In this study, a technique for the optimization of the optical characteristics of multi-channel filters after fabrication is proposed. The multi-channel filter under consideration is based on a Si photonic crystal (PhC), tunable liquid crystal and opto-fluidic technologies. By filling air grooves in the one-dimensional, Si-Air PhC with a nematic liquid crystal, an efficiently coupled multi-channel filter can be realised in which a wide stop band is used for channel separation over a wide frequency range. By selectively tuning the refractive index in various coupled cavities, continuous individual tuning of the central channel (or edge channels) up to 25% of the total channel spacing is demonstrated. To our knowledge, this is the first report on the electro-optical solution for the compensation of fabrication tolerances in an integrated platform.This work has been supported by the ICGEE Programme (Ireland) and NAP-368 (Science Foundation Ireland)

Dynamic in-situ sensing of fluid-dispersed 2D materials integrated on microfluidic Si chip

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.The supplementary videos associated with this article are located in ORE at: https://doi.org/10.24378/exe.1643In this work, we propose a novel approach for wafer-scale integration of 2D materials on CMOS photonics chip utilising methods of synthetic chemistry and microfluidics technology. We have successfully demonstrated that this approach can be used for integration of any fluid-dispersed 2D nano-objects on silicon-on-insulator photonics platform. We demonstrate for the first time that the design of an optofluidic waveguide system can be optimised to enable simultaneous in-situ Raman spectroscopy monitoring of 2D dispersed flakes during the device operation. Moreover, for the first time, we have successfully demonstrated the possibility of label-free 2D flake detection via selective enhancement of the Stokes Raman signal at specific wavelengths. We discovered an ultra-high signal sensitivity to the xyz alignment of 2D flakes within the optofluidic waveguide, which in turn enables precise in-situ alignment detection for the first practicable realisation of 3D photonic microstructure shaping based on 2D-fluid composites and CMOS photonics platform while also representing a useful technological tool for the control of liquid phase deposition of 2D materials.We acknowledge financial support from: The Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom via the EPSRC Centre for Doctoral Training in Electromagnetic Metamaterials (Grant No. EP/L015331/1) and also via Grant Nos. EP/N035569/1, EP/G036101/1, EP/M002438/1, and EP/M001024/1, Science Foundation Ireland Grant No. 12/IA/1300, the Ministry of Education and Science of the Russian Federation (Grant No. 14.B25.31.0002) and the Royal Society International Exchange Grant 2015/R3. The microfluidic structures were fabricated at Tyndall National Institute under the Science Foundation Ireland NAP368 and NAP94 programs

One-dimensional Multi-channel Photonic Crystal Resonators based on Silicon-On-Insulator with High Quality Factor

This is the author accepted manuscript. The final version is available from Frontiers Media via the DOI in this record.We have theoretically and experimentally demonstrated a Fabry-Pérot (FP) resonators based on a Si-air one-dimensional photonic crystal (1D PhC) with coupled triple-cavity modes (or defects). These defects are obtained by filling selected air channels in the 1D PhC with an actively reconfigurable fluid. Simulations of the optical properties of these FP resonators were performed in the wide infrared spectral range. It is shown that by changing the refractive index, nc, of the fluid simultaneously in all three channels, a set of narrow triple resonance peaks can be obtained within wide stop-bands of different order in the infrared range. In addition, at certain values of nc, splitting of the triple resonance peaks into a doublet and a single peak with a significantly larger quality factor, Q=21200, occurs. Prototype devices based on Silicon-On-Insulator platform were fabricated and characterized by electro-optical and spectroscopic measurements. The electro-optical measurements demonstrate the possibility of refractive index manipulation of the filler in the FP channels individually or simultaneously. Spectroscopic measurements performed in the range 1540 – 1630 nm using fibre-coupling confirm the presence of triple resonance peaks in the 3rd stop-band in the absence of an electric field applied to the FP channels. At an applied voltage of 10 V to the middle channel, an increase of Q to 3720 in the single peak is registered which is the highest Q demonstrated in SOI based 1D PhC to date.We acknowledge financial support from: The Engineering Q8 Q19 and Physical Sciences Research Council (EPSRC) of the United Kingdom via the EPSRC Centre for Doctoral Training in Electromagnetic Metamaterials (Grant No. EP/L015331/1 and Grant No. EP/N035569/1) and the Royal Society International Exchange Grant 2015/R3. The microfluidic structures were fabricated at Tyndall National Institute under the Science Foundation Ireland NAP368 and NAP94 programs

Videos of the effect of applied electric fields and laser excitation on the orientation and position of 2D materials dispersed in nematic liquid crystals

1: Orientation switching of a graphene flake, dispersed in E7, in a 50 μm diameter microfluidic reservoir. A pulsed electrical field is applied and a corresponding change in the flake alignment and patterning of the LC surface are observed. The video was taken using cross-polarised light. 2: Induced motion of GO flakes, dispersed in E7, in an 11.6 μm wide channel. A bias is applied across the channel and is steadily increased. Switching of the LC director occurs above a threshold applied field strength of 0.25 V/μm. As the LC director is switched, motion of the dispersed GO flakes is observed. The video was taken with cross-polarised light. 3: Induced motion of a single GO flake, dispersed in MLC-6608, in an 11.6 μm wide channel. An electric field is applied across the channel and is increased and decreased periodically above and below the threshold applied field strength. Induced rotational and translational motion of the flake is observed. The video was taken using unpolarised light. 4: Optically induced motion of GO flakes, dispersed in MLC-6608, in a 50 μm diameter microfluidic reservoir is observed. Motion can be seen as a change in the interference pattern of the backscattered light from the Raman laser. Optical trapping with particles drawn to high light intensity regions is observed.The article associated with this dataset is located in ORE at: http://hdl.handle.net/10871/25352Supplementary videos for the Hogan et al. (2017) article "Dynamic in-situ sensing of fluid-dispersed 2D materials integrated on microfluidic Si chip" published in Scientific Reports.Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Council (EPSRC)Science Foundation IrelandMinistry of Education and Science of the Russian FederationThe Royal Societ