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:
Aug. 18, 2015
Filed:
Jul. 24, 2013
Tso Yee Fan, Belmont, MA (US);
Tso Yee Fan, Belmont, MA (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
Stimulating emission via thulium's lasing transition from theHmanifold to theHmanifold yields light at wavelength of about 820 nm. Unfortunately, excited thulium ions also transition from theHmanifold to the long-livedFmanifold, where they become trapped and can no longer participate in the lasing transition. If the enough of the thulium population becomes trapped in theFmanifold, the gain medium becomes transparent at the pump wavelength, rendering population inversion difficult or impossible. Fortunately, the size of the population in theFmanifold can be limited by selecting an appropriate crystal host and thulium doping concentration, pumping the thulium with pulses shorter than theFmanifold's lifetime, cooling the gain medium to low temperature (e.g., 77 K), stimulating emission from theFmanifold, upconversion pumping of the thulium from theFmanifold to theHmanifold, or transferring energy from thulium in theFmanifold to a co-dopant.