Simulations showing the electric field intensity of a cutoff pillar device with and without a horn antenna structure at the output. Note in this case the base of the device is at the zero point on the vertical axes. The scale is in microns. The resonant mode is a HE11 mode, and resonant wavelength approximately 1.55 microns. (a) Without horn: showing strong divergence of the output light. (b) With a modest horn. Note that already the output beam is much more directional.
