Plasmonic interactions in the metallic nanoaperture array allow for rich phenomena, such as concentration and channeling of light in the subwavelength scale structures. We present high-sensitivity surface plasmon resonance spectroscopy based on a metal nanoslit array. Strong confinement of optical fields in the slit region allows sensitive transduction of surface modification into a shift of surface plasmon resonance wavelength. A metal nanoslit array is also designed to provide spectral filtering in a fashion that is highly scaleable in physical dimension and channel capacity. A spectral sensing technology is presented that can shrink a spectrometer down to a chip-scale, yet offering high sensitivity (~lambda/100) in a broad spectral range (visible to NIR). Overcoming the limitations of diffractive optics, the plasmonics technology is expected to revolutionize the biomedical instrumentation area with it's unique capability in spectroscopy, imaging, and sensing and manipulation of biochemicals.