Central Defect Containing Feedback Photonic Structures for THZ and Infrared Beams Collimation

An idea to form a narrowly-directed electromagnetic beam using a planar photonic crystal with a central defect and mirror reservoir of radiation is developed. We propose here a modified feedback construction which can redirect the extra-beam back into the resonator’s electromagnetic field reservoir. This enables to obtain a collimated unitary outgoing beam without a loss of intensity. The properties of standing modes inside the polyethylene (polyethylene)/silicon plane resonators in the total intrinsic reflection region and unusual manifestations of THz and IR transmission spectra were studied. It is shown that the angle and frequency half-widths of the resonance peaks can be less than 10−9 of the magnitude of angle and frequency depending on the number of periods. This allows one to form collimated beams with divergence measured in fractions of a microdegree. Due to a property of this kind resonators to transform the frequency dependent peaks into the outgoing-transmitted beams of various directions like a prism transforms light a way for precision measurements of angular and frequency distribution of THz radiation is opened. The high extent of collimation resulting from the usage of photonic resonator gives an opportunity to form long and stable channels of communication in the THz frequency range.