arXiv subjects

José Viana-Gomes

Publications and source records attributed to José Viana-Gomes.

5 recordsLinked to original sources

arXiv2021

Mode-center Placement of Monolayer WS$_{2}$ in a Photonic Polymer Waveguide

Effective integration of 2D materials such as monolayer transition metal dichalcogenides (TMDs) into photonic waveguides and integrated circuits is being intensely pursued due to the materials' strong exciton-based optical response. Here, we present a platform where a WS$_{2}$-hBN 2D heterostructure is directly integrated into the photonic mode-center of a novel polymer ridge waveguide. FDTD simulations and collection of photoluminescence from the guided mode indicate that this system exhibits significantly improved waveguide-emitter coupling over a previous elastomer platform. This is facilitated by the platform's enhanced refractive-index contrast and a new method for mode-center integration of the coupled TMD. The integration is based on a simple dry-transfer process that is applicable to other 2D materials, and the platform's elastomeric nature is a natural fit to explore strain-tunable hybrid-photonic devices. The demonstrated ability of coupling photoluminescence to a polymer waveguide opens up new possibilities for hybrid-photonic systems in a variety of contexts.

physics.optics↗

arXiv2019

Mapping a quantum walk by tuning the coupling coefficient

We present a method to map the evolution of photonic random walks that is compatible with nonclassical input light. Our approach leverages a newly developed flexible waveguide platform to tune the jumping rate between spatial modes, allowing the observation of a range of evolution times in a chip of fixed length. In a proof-of-principle demonstration we reconstruct the evolution of photons through a uniform array of coupled waveguides by monitoring the end-face alone. This approach enables direct observation of mode occupancy at arbitrary resolution, extending the utility of photonic random walks for quantum simulations and related applications.

quant-ph↗

arXiv2019

Elastomeric waveguide on-chip coupling of an encapsulated MoS$_2$ monolayer

We propose a robust photonic platform for encapsulation and addressing of optically active 2D- and nano-materials. Our implementation utilises a monolayer of MoS$_2$ transition metal dichalcogenide embedded in an elastomeric waveguide chip. The structure is manufactured from PDMS using soft-lithography and capable of sustaining a single mode of guided light. We prove that this setup facilitates addressing of the 2D material flake by pumping it with polarised laser light and gathering polarisation-resolved photoluminescence spectra with the extinction ratio of 31, which highlights the potential for selection-rule dependent measurements. Our results demonstrate improved handling of the material and experimental simplification compared to other techniques. Furthermore, inherent elasticity of the host provides an avenue for direct mechanical coupling to embedded materials.

physics.app-ph↗

arXiv2018

Tunable interferometers on a flexible polymer chip

To facilitate the implementation of large scale photonic quantum walks, we have developed a polymer waveguide platform capable of robust, polarization insensitive single mode guiding over a broad range of visible and near- infrared wavelengths. These devices have considerable elasticity, which we exploit to enable tuning of optical behaviour by precise mechanical deformations. In this work, we investigate pairs of beamsplitters arranged as interferometers. These systems demonstrate stable operation over a wide range of phases and reflectivities. We discuss device performance, and present an outlook on flexible polymer chips supporting large, reconfigurable optical circuits.

physics.app-ph↗

arXiv2018

Mechanically tunable integrated beamsplitters on a flexible polymer platform

We report the development of a monolithic, mechanically tunable waveguide platform based on the flexible polymer polydimethyl siloxane (PDMS). Such devices preserve single mode guiding across a wide range of linear geometric distortions. This enables the realization of directional couplers with tunable splitting ratios via elastic deformation of the host chip. We fabricated several devices of this type, and verified their operation over a range of wavelengths, with access to the full range of input/output ratios. The low cost and relative ease of fabrication of these devices via a modified imprint lithographic technique make them an attractive platform for investigation of large scale optical random walks and related optical phenomena.

physics.optics↗