SPEAKER
Professor Anna Baldycheva, EPSRC Centre for Graphene Science, University of Exeter
ABSTRACT
Currently, innovation of novel reconfigurable materials, which can be integrated on-chip with CMOS compatible processes and used for the engineering of devices, is the key driver for realization of future chip-scale multi-functional systems. Among recently emerged optoelectronic materials, fluid-dispersed atomically thin two-dimensional (2D) nanocomposite materials have sparked a great level of interest for their promise as in-situ tailored metamaterial device platforms for the next generation of multi-functional (opto)-electronic systems with a wide range of important applications, such as renewable energy, optical communications, bio-chemical sensing, and security and defence technologies. Dynamically controlled, three-dimensional, self-assembly of suspended, 2D liquid-exfoliated nano-flakes not only provides a breakthrough route for technological realization of 2D material-based 3D device architectures, but also its fluidic nature allows CMOS-compatible integration on chip using microfluidic technology. This opens up almost limitless possibilities in the fabrication of compact and low-power systems for the realisation of commercially viable, miniaturised, multi-functional light-management devices, for example light sources, tuneable optical filters and nano-antenna phased arrays. An example of a future device can be seen in Fig.1, where dynamically reconfigurable 2D material fluid metastructures are integrated into a microfluidic system and coupled with a CMOS photonic circuit.
In the first part of my talk, I will demonstrate the possibility of low-power controllable manipulation of 2D nano-objects, directly on chip, utilizing fundamental tuning approaches in Si photonics: electro-optic and thermo-optic effects, as well as discuss the first practicable 2D fluid composite based device designs for application in integrated photonics. I will further focus on the dynamics of 2D nanoplatelet spatial alignment, the understanding of which is essential for the first practicable realisation of three-dimensional metastructure formation on-chip. Through the optimization of SOI (silicon-on-insulator) based optofluidic system design to enable simultaneous in-situ Raman spectroscopy monitoring of 2D dispersed flakes during the device operation we have sucessfully demonstrated the possibility, for the first time, of label-free 2D flake detection via selective enhancement of the Stokes Raman signal at given wavelengths. This approach has then been applied to monitor the individual 2D nanoplatelet dynamics within a microfluidic channel on chip during application of external stimuli. We discovered an ultra-high signal sensitivity to the xyz alignment of 2D flakes within the opto-fluidic channel, which in turn enables precise in-situ alignment detection for the first practicable realization of 3D photonic microstructure shaping based on 2D-fluid composites and CMOS photonics platform.