Counterintuitively, shining light through an array of subwavelength-diameter holes can increase the transmission efficiency by orders of magnitude over that predicted by simple diffraction theory. Scientists at Seoul National University, Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Korea Research Institute of Standards and Science, Korea Advanced Institute of Science and Technology and Korea University have confirmed that the coherent interference of surface plasmon waves from the surface surrounding the holes determines the near-field emission patterns and that the first two diffraction orders survive into the far field.

Reporting in the Oct. 21 issue of Applied Physics Letters, the team employed scanning optical microscopy in the work, with a Ti:sapphire laser illuminating patterned samples of gold-coated sapphire. The near-field patterns (left) displayed striped patterns perpendicular to the direction of polarization of the laser. The far-field patterns (right) were sinusoidal, depending on the excitation wavelength.