Near-field microscope probe for far infrared time domain measurements

A near-field probe fabrication technique for far-infrared frequencies based on photoconducting antennas is developed. A subwavelength-size field source is accomplished by means of an aperture and protruding high refractive index tip. The near-field probe is tested by using free space traveling electromagnetic pulses with a broadband spectrum in the range of 0.3-1.5 THz. A spatial resolution of 60 mu m is achieved for a 50 mu m aperture. The described probe may be used for near-field transmission microscopy in illumination and collection modes. Resolution may be further improved by means of a smaller aperture. (C) 2000 American Institute of Physics. [S0003-6951(00)04630-1].