DMSE Doctoral Thesis Defense

Chalcogenide Glass on Layered van der Waals Crystals for Integrated Photonic Devices

Skylar Deckoff-Jones

Wednesday, March 10, 2021 

9:00 – 10:00 AM EDT

Email dmse-gradoffice@mit.edu for link.

Layered van der Waals (vdW) materials have demonstrated huge potential for photonic devices with their varied and tunable optical properties. They can be integrated into planar photonic devices on virtually any substrate due to their van der Waals bonding, thereby introducing desirable material properties to existing integrated photonic platforms.  Previously, their utilization has been limited to their transfer onto prefabricated photonic structures, limiting device design, and often introducing undesirable stress or fracture. Recently, the integration of vdW materials with chalcogenide glasses (ChG) has been developed for near and mid-infrared integrated photonic applications. This ChG-on-vdW platform enables new device architectures that can better utilize vdW material’s strong anisotropy and accelerates prototyping.

In this work, we leverage the ChG-on-vdW material platform to demonstrate integrated photonic devices with enhanced performance, while also gaining further insight into the vdW material’s properties. First, we show that ChG processing does not damage vdW materials, while even serving as a passivation layer for unstable vdW materials such as black phosphorus. We then fabricate and characterize black phosphorus and tellurene based mid-infrared photodetectors, which not only achieve high sensitivity, but also give insight to the critical role of vdW material anisotropy in photodetection. Next, we utilize the strong second order nonlinearity in indium selenide and tellurene to investigate vdW semiconductor’s linear elecrooptic Pockels effect: an essential, yet elusive, effect to realize high-performance waveguide integrated optical modulators. Finally, we show how gallium sulfide’s use in hybrid waveguides can enhance the waveguide optical nonlinearity, which we use to demonstrate all-optical modulation.  Cumulatively, this work demonstrates the power of the ChG-on-vdW platform and shows the promise of using vdW materials to engineer future generations of integrated photonic devices.

Thesis Supervisors 

Juejun Hu, Associate Professor, Materials Science and Engineering, Massachusetts Institute of Technology

Thesis Committee 

Silvija Gradečak, Visiting Professor, Materials Science and Engineering, Massachusetts Institute of Technology

Jeffrey Grossman, Morton and Claire Goulder and Family Professor, Materials Science and Engineering, Massachusetts Institute of Technology