Development of coherent nanophotonic UV sources

"It has been shown theoretically and experimentally, that one-dimensional photonic bandgap (1DPBG) structures enhance nonlinear effects for one to three orders of magnitude. By exploiting these effects, one can achieve efficient frequency conversion (secondand third harmonic generation, and parametric) in materials with modest nonlinear optical properties and in structures with a total path length on the order of micrometers. By the integration of 1DPBG structures with an existing visible laser diode, onecan achieve bright, coherent sources of deep UV light, limited only by the absorption edge of materials used in these structures. HexaTech, Inc., and NCSU will combine their expertise in wide bandgap nitrides and photonics to develop a process forfabrication of nanometer scale 1DPBG structures based on AlN. AlN has a bandgap of 6.28 eV and sufficiently large NLO coefficients (d15 = 4 pm/V, d33 = 5 pm/V) to meet all criteria for successful operation down to 200 nm in wavelength. It is important tonote that this wavelength limit is much lower than the theoretical limit for classical AlxGa1-xN laser structures. This approach also bypasses the issue of doping of alloys with high Al content, which remains a serious challenge for classical devices.Intense UV light sources based on efficient frequency conversion in the proposed one-dimensional photonic bandgap structures will find immediate applications ranging from multipurpose sensors of chemical agents and moieties of biological origin in the airabove a terrestrial battlefield to optical communications and data processing in space."