A Search for Stimulated Emission of Radiation From Superconducting Tunnel Junctions

A report is made of an exhaustive search for stimulated emission of energy gap radiation from superconducting tunnel junctions of the form Ta–oxide–A1. Two types of radiation detectors have been employed—bolometers for broad band detection and a superconducting frequency converter tunable in the range of interest for narrow band work. The present search has been completely unsuccessful and this negative result has spurred a reexamination of both the theory and the experiments. Serious doubts are raised as to the validity of earlier claims and it is concluded that the previous probable observation of radiative emission requires a different interpretation.