ULTRA-COMPACT ON-CHIP INTEGRATED SPECTROMETERS BASED ON METASURFACES

SPECTROMETERS ARE POWERFUL TOOLS THAT ARE WIDELY USED IN CHEMICAL AND BIOLOGICAL SENSING MATERIAL CHARACTERIZATION AND ANALYSIS OF ASTRONOMICAL OBJECTS. THE DEVELOPMENT OF A HIGH-RESOLUTION ON-CHIP SPECTROMETER COULD ENABLE COMPACT VERSATILE ENERGY-EFFICIENT SPECTROSCOPY FOR PORTABLE SENSORS AS WELL AS INCREASING LAB-ON-CHIP FUNCTIONALITY. HOWEVER INTEGRATED SPECTROMETERS BASED ON GRATINGS REQUIRE LARGE FOOTPRINTS WHILE THE ONES BASED ON HOLOGRAPHY HAVE LIMITED SENSITIVITY. IN THIS PROGRAM WE AIM TO ADDRESS THESE CRITICAL CHALLENGES OF CREATING AN ULTRA-COMPACT ON-CHIP INTEGRATED SPECTROMETER WITH HIGH RESOLUTION HIGH SENSITIVITY AND A SMALL FOOTPRINT. WE WILL CRAFT THE INTEGRATED SPECTROMETERS USING THE NEWLY EMERGING METASURFACE TECHNOLOGY. A METASURFACE IS AN ULTRATHIN ENGINEERED NANOSTRUCTURE THAT HAS THE CAPABILITY OF LOCALLY TAILORING THE PROPERTIES OF LIGHT AT THE NANOSCALE. IT OFFERS TREMENDOUS POWER FOR MANIPULATING LIGHT. SO FAR METASURFACES USUALLY DESIGNED TO WORK FOR THE LIGHT THAT PROPAGATES IN THE FREE SPACE. HERE WE WILL COMBINE THE METASURFACE WITH THE INTEGRATED PHOTONIC WAVEGUIDES BY PUTTING METASURFACE ELEMENTS ON THE TOP OF THE WAVEGUIDES SO THAT WE WILL BE ABLE TO CONTROL THE GUIDED OPTICAL MODES. THE RESONATING METASURFACE ELEMENTS WILL INTRODUCE ABRUPT PHASE SHIFTS TO THE GUIDED WAVE THROUGH EVANESCENT COUPLING. DUE TO THE WAVELENGTH SENSITIVITY OF THE RESONANCE - WHICH CAN BE DESIGNED TO BE VERY HIGH THE PROVIDED PHASE SHIFT WILL GREATLY DEPEND ON THE WAVELENGTH OF THE INPUT LIGHT. ADDITIONALLY BY SPATIALLY DISTRIBUTING DIFFERENT METASURFACE ELEMENTS ALONG THE WAVEGUIDE WE ARE ABLE TO CREATE A SPATIAL PHASE PROFILE FOR THE GUIDED LIGHT. WITH THAT WE CAN SEPARATE THE LIGHT BY ITS WAVELENGTH OR CONVERT THE WAVELENGTH INFORMATION TO SPATIAL LIGHT INTENSITY DISTRIBUTION. THEREFORE THE WAVELENGTH INFORMATION CAN BE EASILY READ OUT BY INTEGRATED PHOTODETECTORS. THE PROPOSED APPROACH WILL BE VALIDATED THROUGH ELECTROMAGNETIC THEORY FULLWAVE SIMULATIONS AND EXPERIMENTAL DEMONSTRATION OF NANOFABRICATED DEVICES. THIS EFFORT WILL ENABLE US TO BUILD A COMPACT ON-CHIP INTEGRATED SPECTROMETER WHICH CAN SIMULTANEOUSLY ACHIEVE HIGH SPECTRAL RESOLUTION HIGH SENSITIVITY AND A SMALL DEVICE FOOTPRINT. IT WILL BE FULLY COMPATIBLE WITH THE CURRENT PHOTONIC INTEGRATED CIRCUITS. THE PROPOSED TECHNOLOGY WILL OFFER A UNIQUE PLATFORM FOR DEVELOPING MINIATURIZED SPECTROSCOPY FOR A NEW VARIETY OF LAB-ON-CHIP APPLICATIONS AND INTEGRATED PHOTONIC SENSORS. THE ADVANCES GAINED THROUGH THIS RESEARCH PROGRAM WILL HAVE LONG-LASTING IMPACT FOR BOTH SOCIETY AND INDUSTRY THAT GO FAR BEYOND THE EXPLICIT GOALS STATED HERE. A NEW PLATFORM BASED ON HYBRIDIZING METASURFACES AND INTEGRATED PHOTONICS WILL BE ESTABLISHED FOR THE FUTURE DEVELOPMENT OF DISRUPTIVELY COMPACT ENERGY-EFFICIENT AND HIGH-SPEED OPTICAL ARCHITECTURES. IT WILL HAVE WIDE APPLICATION ACROSS THE SPECTRUM OF NASA SCIENCE NEEDS PARTICULARLY WHERE THE GRAND CHALLENGES OF THE SYSTEM SIZE WEIGHT AND POWER PERFORMANCE (SWAP2) ARE CONCERNED. NOTABLY THIS PROGRAM IS IN DIRECT ALIGNMENT WITH NASA TECHNOLOGY ROADMAPS ADDRESSING SOME CRITICAL TOPICS SUCH AS REMOTE SENSING INSTRUMENTS/SENSORS IN-SITU INSTRUMENTS/SENSORS AND SENSORS ELECTRONICS AND DEVICES.