Tailoring a high-transmission fiber probe for photon scanning tunneling microscope

Transmission efficiency of a fiber probe used in photon scanning tunneling microscope is evaluated as a function of aperture diameter. The apertured probe has been fabricated by chemical etching technique and metal coating. By comparing two types of probes with different cone angles, we determine the most influential factor in the transmission property of the metal-cladding tapered waveguide. A long tip with high efficiency is developed by a multistep etching method so as to be suitable during actual scanning operation. Photoluminescence imaging of lateral p-n junctions on the GaAs substrate is demonstrated in the illumination-collection hybrid mode operation of photon scanning tunneling microscope.