US 11,862,926 B2
High power cladding pumped single mode fiber Raman laser fees
Valentin Gapontsev, Worcester, MA (US); Igor Samartsev, Westborough, MA (US); and Nikolai Platanov, Worcester, MA (US)
Assigned to IPG PHOTONICS CORPORATION, Marlborough, MA (US)
Appl. No. 16/613,463
Filed by IPG PHOTONICS CORPORATION, Oxford, MA (US)
PCT Filed May 14, 2018, PCT No. PCT/US2018/032539
§ 371(c)(1), (2) Date Nov. 14, 2019,
PCT Pub. No. WO2019/013862, PCT Pub. Date Jan. 17, 2019.
Claims priority of provisional application 62/506,278, filed on May 15, 2017.
Prior Publication US 2021/0159662 A1, May 27, 2021
Int. Cl. H01S 3/30 (2006.01); H01S 3/067 (2006.01); H01S 3/08045 (2023.01); H01S 3/094 (2006.01); H01S 3/17 (2006.01)
CPC H01S 3/302 (2013.01) [H01S 3/0675 (2013.01); H01S 3/06733 (2013.01); H01S 3/08045 (2013.01); H01S 3/094007 (2013.01); H01S 3/094038 (2013.01); H01S 3/094042 (2013.01); H01S 3/094053 (2013.01); H01S 3/094069 (2013.01); H01S 3/176 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A high power single mode (SM) Raman laser source comprising:
an end pumped multi-clad Raman fiber having:
an inner cladding, which receives multimode (MM) pump radiation propagating along a path at a wavelength λpump, and
a MM core surrounded by the inner cladding and provided with a central core region which has a diameter smaller than that of the MM core, the pump radiation producing Raman scattering which induces a conversion of the pump radiation to a signal radiation at a Raman-shifted wavelength λram>than wavelength λpump,
the central core region being dimensioned to confine a fundamental mode (FM) of the signal radiation and doped with Raman gain enhancing impurities and silica refractive index decreasing impurities which provide the MM core including the central core region with a uniform refractive index; and
spaced wavelength-selective reflectors defining therebetween a resonator for the FM at the wavelength λram which at least partially includes the central core region, the wavelength-selective reflectors each being dimensioned to have a diameter which does not exceed the diameter of the central core region, wherein the Raman fiber outputs the signal radiation in the FM with an 1≤M2≤1.1 in a power range between a few kilowatts (kW) and tens of kWs.