Polarizing 50μm core Yb-doped photonic bandgap fiber

Polarizing optical fibers are important components for building compact fiber lasers with linearly polarized laser output. Conventional single-mode optical fibers with birefringence can only preserve the polarization when the incident beam is launched properly. Recent reports demonstrate that the birefringence in photonic bandgap fibers (PBFs) can provide single-polarization operation near the edge of transmission band by shifting the transmission band for the light with orthogonal polarizations. Here, we demonstrate a 50μm core Yb-doped polarizing photonic bandgap fiber (PBF) for single-polarization operation throughout the entire transmission band from 1010nm to 1170nm with a polarization extinction ratio (PER) of >5dB/m, which is >15dB/m near the short wavelength edge of the transmission band. The polarizing effect is due to the differential polarization transmission loss presented in this fiber, which is benefited from the fiber birefringence of 3.2x10-4, obtained by incorporating low-index boron-doped rods on either side of the core. The achievement is based on the fact that light at fast axis has lower effective mode index which is closer to the modes in the photonic cladding and thus to be easily coupled into cladding. A 2.6m long straight fiber was tested in a laser configuration without any polarizers to achieve single polarized laser output with a PER value of 21dB at 1026nm lasing wavelength.

[1]  Kunimasa Saitoh,et al.  Ytterbium-doped large-mode-area all-solid photonic bandgap fiber lasers. , 2014, Optics express.

[2]  Katsuhiro Takenaga,et al.  Single-polarization operation in birefringent all-solid hybrid microstructured fiber with additional stress applying parts. , 2009, Optics letters.

[3]  Christopher Dunn,et al.  Flat-top mode from a 50 µm-core Yb-doped leakage channel fiber. , 2013, Optics express.

[4]  Arlee V. Smith,et al.  Mode instability in high power fiber amplifiers. , 2011, Optics express.

[5]  Liang Dong,et al.  Stimulated thermal Rayleigh scattering in optical fibers. , 2013, Optics express.

[6]  John Canning,et al.  Spun elliptically birefringent photonic crystal fibre. , 2007, Optics express.

[7]  J. Rothhardt,et al.  Single-polarization ultra-large-mode-area Yb-doped photonic crystal fiber. , 2008, Optics express.

[8]  Sébastien Février,et al.  Very-large-mode-area photonic bandgap Bragg fiber polarizing in a wide spectral range. , 2011, Optics letters.

[9]  Yves Jaouën,et al.  Ytterbium-doped solid core photonic bandgap fiber for laser operation around 980nm , 2008 .

[10]  J. Limpert,et al.  Stress-induced single-polarization single-transverse mode photonic crystal fiber with low nonlinearity. , 2005, Optics express.

[11]  K. Saitoh,et al.  Mode area scaling with all-solid photonic bandgap fibers. , 2012, Optics express.

[12]  B. Ward,et al.  Origin of thermal modal instabilities in large mode area fiber amplifiers. , 2012, Optics express.