  We demonstrate surface plasmon-induced enhancements in optical imaging and
spectroscopy on silver coated silicon nanocones which we call black silver
substrate. The black silver substrate with dense and homogeneous nanocone
forest structure is fabricated on wafer level with a mass producible
nanomanufacturing method. The black silver substrate is able to efficiently
trap and convert incident photons into localized plasmons in a broad wavelength
range, which permits the enhancement in optical absorption from UV to NIR range
by 12 times, the visible fluorescence enhancement of ~30 times and the NIR
Raman scattering enhancement factor up to ~108. We show a considerable
potential of the black silver substrate in high sensitivity and broadband
optical sensing and imaging of chemical and biological molecules.
