Ultrafast All-Optical Switching of Germanium-Based Flexible Metaphotonic Devices

Wen Xiang Lim; Manukumara Manjappa; Yogesh Kumar Srivastava; Longqing Cong; Abhishek Kumar; Kevin F MacDonald; Ranjan Singh

doi:10.1002/adma.201705331

Ultrafast All-Optical Switching of Germanium-Based Flexible Metaphotonic Devices

Adv Mater. 2018 Mar;30(9). doi: 10.1002/adma.201705331. Epub 2018 Jan 12.

Authors

Wen Xiang Lim^{1

2}, Manukumara Manjappa^{1

2}, Yogesh Kumar Srivastava^{1

2}, Longqing Cong^{1

2}, Abhishek Kumar^{1

2}, Kevin F MacDonald³, Ranjan Singh^{1

2}

Affiliations

¹ Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
² Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
³ Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton, SO17 1BJ, UK.

PMID: 29327454
DOI: 10.1002/adma.201705331

Abstract

Incorporating semiconductors as active media into metamaterials offers opportunities for a wide range of dynamically switchable/tunable, technologically relevant optical functionalities enabled by strong, resonant light-matter interactions within the semiconductor. Here, a germanium-thin-film-based flexible metaphotonic device for ultrafast optical switching of terahertz radiation is experimentally demonstrated. A resonant transmission modulation depth of 90% is achieved, with an ultrafast full recovery time of 17 ps. An observed sub-picosecond decay constant of 670 fs is attributed to the presence of trap-assisted recombination sites in the thermally evaporated germanium film.

Keywords: flexible metamaterial device; germanium; terahertz modulation; ultrafast photoswitching.