His work on nanophotonics includes the first optical nanostructures custom designed by optimization for specific optical functions, which is arguably the start of the field of inverse design of complex optical devices in photonics, plasmonic and nanometallic waveguides and antennas for concentrating light into photodetectors, including nanophotonic enhancement and control of wavelength sensitive detectors, superprism wavelength splitters based on dielectric stack structures, and other nanophotonic structures and devices. He also showed various novel limits to optical components generally, including nanophotonic structures.