Use of a scanning tunneling microscope to rectify optical frequencies and measure an operational tunneling time

This paper elaborates on the idea, recently advanced by the authors, of using the scanning tunneling microscope (STM) in new experiments on laser frequency synthesis and laser rectification at optical frequencies. We first introduce the subject of harmonic generation and mixing of laser beams by the related tunneling device called “point contact diode.” Then, we present new quasistatic current-voltage characteristics of several STM junctions, emphasizing their nonlinear and rectifying aspects. The physical origin of the observed asymmetrical I-V curves is discussed. Finally, we describe the proposed rectification experiment which should result in an operationally meaningful definition of a tunneling time for electrons crossing an STM junction and we present some very preliminary results. © 1988, American Vacuum Society. All rights reserved.