Electronics Weekly
The current discovery grew out of 30 years of basic research, stemming from an initial discovery of selenite-respiring bacteria that form discrete packets of elemental selenium.
“From there, it was a step down the periodic table to learn that the same could be done with tellurium oxyanions,” said Ron Oremland of the US Geological Survey. “The fact that tellurium had potential application in the realm of nanophotonics came as a serendipitous surprise.”
The elemental tellurium particles produced can be ordered within composite materials, particularly suited to mid-infra-red photonic applications, according to Werner Blau of Trinity College Dublin. “This wavelength region is becoming a hot technological topic as it is useful for biomedical, environmental and security-related sensing, as well as laser processing and for opening up new windows for fibre optical and free-space communications,” he said.
Non-linear optical measurements of such materials reveal strong saturable absorption and non-linear optical extinctions induced by Mie scattering over broad time and wavelength ranges.
To prove their usefulness, bacteria-made tellurium crystals were demonstrated passive mode-locking and Q-switching in ultra-fast 1.55μm lasers.
The research group is broadly based – along with the University of Houston, the US Geological Survey and Trinity College, other institutions involved include Shanghai Jiao Tong University and the Shanghai Institute of Optics and Fine Mechanics at the Chinese Academy of Sciences.
For the non-linear-optically-inclined, detailed information has been made freely available by Nature communications, in the paper ‘Bacterially synthesized tellurium nanostructures for broadband ultrafast nonlinear optical applications‘.
