US 7,542,488 B2
Fiber laser
Holger Schlueter, Princeton, N.J. (US); and Rolf Biekert, Farmington, Conn. (US)
Assigned to Trumpf, Inc., Farmington, Conn. (US)
Filed on Jan. 26, 2004, as Appl. No. 10/763,390.
Claims priority of provisional application 60/470446, filed on May 15, 2003.
Claims priority of provisional application 60/442123, filed on Jan. 24, 2003.
Prior Publication US 2004/0218635 A1, Nov. 04, 2004
Int. Cl. H01S 3/30 (2006.01)
U.S. Cl. 372—6  [385/127] 29 Claims
OG exemplary drawing
 
1. An optical fiber for producing laser radiation at a characteristic wavelength, the optical fiber comprising:
a first multimode core region having a first index of refraction, the core region being adapted for guiding the laser radiation in a longitudinal direction of the fiber and adapted for guiding pump radiation; and
an active region embedded within the core region for producing radiation at the characteristic wavelength when pumped by pump radiation, the active region having a transverse dimension smaller than the characteristic wavelength such that less than about 10% of the radiation produced at the characteristic wavelength in the active region is confined to the active region and such that the optical fiber has a gain along its longitudinal direction that is sufficiently small so that a desired laser mode is above its lasing threshold while all other modes are below their lasing threshold.