The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 07, 2015
Filed:
May. 19, 2014
Riken, Saitama, JP;
Riken, Wako-shi, JP;
Abstract
To raise the upper limit of the temperature range in which a quantum cascade laser (QCL) element for THz range operates at a single frequency. In a quantum cascade laser element in one embodiment of the present invention, each unit structureU in the active regionis provided with the first to fourth well layersW-Wthat are stacked in this order and separated from one another by at least one bather layerB. During application of a first bias electric field for lasing, the structure of electronic energy levels has a reception, upper lasing, lower lasing, and depopulation levels and emits electromagnetic waves at a first frequency. During application of a second bias electric field that is weaker than the first bias electric field, the overlap integral is 0.15 or less between electronic wavefunctions for the unnecessary upper lasing and unnecessary lower lasing levels, thereby stimulated emissions of electromagnetic waves are suppressed at frequencies other than the first frequency.