Univ of Illinois Micro + Nanotechnology Lab 2016 Highlights Report | Page 6

Advancing a novel brain imaging method
VCSEL arrays with record high modulation bandwidth
Catherine Best ’ s team performed the first-ever high-resolution imaging of the mouse brain using spatial light interference microscopy .

Advancing a novel brain imaging method

Research Assistant Professor Catherine Best and MNTL affiliate faculty member Gabriel Popescu led a team of researchers that performed the first-ever high-resolution imaging of the mouse brain using spatial light interference microscopy ( SLIM ). A quantitative imaging technique , SLIM had previously only been used to image single neurons in the mouse brain . Unlike other imaging methods that require fluorescent dyes that limit their use to rodent models , SLIM can provide unprecedented quantitative cytostructural information across multiple regions in the brain at the anatomical level for multiple animal brain models . In addition , the technique provides Corpus callosum fiber angle of orientation in coronal and sagittal sections . Best ’ s results indicate that , in principle , SLIM can computationally produce a 3D rendering of the entire mouse brain , which would enable researchers to observe all the brain connections from the nanometer to centimeter scale .
Source : Scientific Reports , “ Label-free , multi-scale imaging of ex-vivo mouse brain using spatial light interference microscopy ,” December 23 , 2016 .

VCSEL arrays with record high modulation bandwidth

The data rate for optical digital communication systems continues to increase to satisfy the demands of the Internet . This in turn requires continual improvement of the semiconductor optical device technologies that are used in digital interconnects . For short distance interconnects , the dominant laser source is the vertical cavity surface emitting laser ( VCSEL ), an optoelectronic technology that ECE Professor Kent Choquette and his Photonic Device Research Group have pursued for more than two decades . Recently Choquette ’ s group has developed optically coupled photonic crystal VCSELs that exhibit record high modulation bandwidth . By using two optically coupled VCSELs that emit coherently , the modulation bandwidth which previously was less than 30 GHz from a single laser , has been increased to nearly 40 GHz , which will enable a significant increase in the data rate . These coherent laser arrays also have improved output power and significantly reduced emission linewidth , which are critical parameters for optical interconnects .
Source : Proceedings SPIE , ““ Low dispersion ultrahigh bandwidth vertical cavity surface emitting laser arrays ,” March 18 , 2016 .
A top view of a photonic crystal VCSEL array fabricated by Professor Kent Choquette ’ s Photonic Device Research Group .
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