US 12,444,896 B2
Optical fiber devices and methods for directing stimulated raman scattering (SRS) light out of a fiber core and into a cladding
Tyson L. Lowder, Vancouver, WA (US); Dahv A.V. Kliner, Portland, OR (US); and C. Geoffrey Fanning, Portland, OR (US)
Assigned to nLIGHT, Inc., Camas, WA (US)
Appl. No. 17/418,699
Filed by nLIGHT, Inc., Camas, WA (US)
PCT Filed Dec. 19, 2019, PCT No. PCT/US2019/067547
§ 371(c)(1), (2) Date Jun. 25, 2021,
PCT Pub. No. WO2020/139706, PCT Pub. Date Jul. 2, 2020.
Claims priority of provisional application 62/786,175, filed on Dec. 28, 2018.
Prior Publication US 2022/0094130 A1, Mar. 24, 2022
Int. Cl. H01S 3/067 (2006.01); G02B 6/02 (2006.01); H01S 3/30 (2006.01)
CPC H01S 3/06729 (2013.01) [G02B 6/02085 (2013.01); H01S 3/302 (2013.01); G02B 6/0208 (2013.01); H01S 3/06733 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An optical fiber device, comprising:
a first and a second length of optical fiber, each of the lengths of optical fiber comprising a core and two or more cladding layers, wherein the core supports at least a first propagation mode for light comprising both signal spectrum and Raman spectrum, the Raman spectrum comprises one or more first wavelengths that are longer than one or more second wavelengths of the signal spectrum, the two or more cladding layers of at least the first length of optical fiber comprise an inner cladding layer and an outer cladding layer in contact with the inner cladding layer; and
a chirped fiber Bragg grating (CFBG) between the first and second lengths of fiber, the CFBG to couple at least some of the light propagated in the first propagation mode into one or more cladding modes of the first or second length of fiber with a greater coupling efficiency over the Raman spectrum than over the signal spectrum, the CFBG comprises a third length of optical fiber further comprising a core, an inner cladding layer, and an outer cladding layer in contact with the inner cladding layer, wherein a refractive index of the core alternates between two values as a function of a periodicity of the CFBG that varies over the third length of optical fiber;
an optical oscillator to excite at least the signal spectrum, and the optical oscillator coupled to the first length of optical fiber with the CFBG between the optical oscillator and the second length of optical fiber, wherein the CFBG is to couple the first propagation mode into one or more counter-propagating cladding modes supported by the inner cladding layer of the first length of optical fiber; and
a cladding light stripper CLS to dissipate light from the cladding mode, the CLS comprising a fourth length of optical fiber having one or more cladding features to perturb light propagating in the cladding mode, the fourth length of optical fiber being located between the optical oscillator and the CFBG to exclude the light from the cladding mode from reaching the optical oscillator.