Photo-elastic effect, thermal lensing and depolarization in<i>a</i>-cut tetragonal laser crystals

Yumashev, K. V.; Zakharova, A N; Loiko, Pavel

doi:10.1088/1054-660x/26/6/065002

Cited by 8 publications

(2 citation statements)

References 34 publications

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“…This is due to the photo-elastic effect [41]. The fs direct laser writing induces an anisotropic stress field [20] which locally changes the orientation and shape of the optical indicatrix of the crystal [42] allowing the light beam to have a polarization component along the orientation of the analyzer. Note that the refractive-index changes are strongly localized around damage tracks which appear to be bright under a close view, Fig.…”

Section: A Confocal Laser Microscopymentioning

confidence: 99%

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

Kifle

Loiko

Romero

et al. 2020

J. Lightwave Technol.

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We report on the first active surface Y-branch waveguide in the ∼2 µm spectral range. Depressed-cladding rectangular-cross-section surface waveguides with a splitting ratio of 1 × 2 are fabricated by femtosecond direct laser writing in a thulium (Tm 3+ ) doped monoclinic double tungstate crystal. Confocal laser microscopy and µ-Raman spectroscopy reveal well preserved crystallinity of the waveguide core. Under high-brightness laser pumping at 0.8 µm, a simultaneous continuous-wave laser operation in both arms is achieved resulting in a total output power of 0.46 W at ∼1.84 µm with a slope efficiency of 40.6% and a laser threshold of 0.28 W. The laser output is linearly polarized and spatially multimode (TE 12 /TE 22 ) with a power splitting ratio between arms of 52.1/47.9%). The waveguide propagation losses at 1.84 µm are ∼1.6 dB/cm and the loss from the Y-junction is 0.1 dB. The fabricated waveguides represent a route towards advanced photonic micro-structures such as a Mach-Zehnder interferometer for bio-sensing at ∼2 µm.

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Section: A Confocal Laser Microscopymentioning

confidence: 99%

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

Kifle

Loiko

Romero

et al. 2020

J. Lightwave Technol.

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show abstract

“…6(a). This stress field leads to the stress-induced birefringence via the photo-elastic effect [63] and favors the polarization response of the WG.…”

Section: Fabrication and Characterization Of Waveguidesmentioning

confidence: 99%

Watt-level ultrafast laser inscribed thulium waveguide lasers

Kifle

Loiko

Romero

et al. 2020

Progress in Quantum Electronics

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We report on the first watt-level ultrafast laser inscribed Thulium waveguide (WG) lasers. Depressed-index buried channel WGs with a circular cladding (type III) are produced in monoclinic Tm 3þ :KLu(WO 4 ) 2 crystals. Laser operation is achieved under conventional ( 3 H 6 → 3 H 4 ) and in-band ( 3 H 6 → 3 F 4 ) pumping. In the former case, employing a Raman fiber laser emitting at 1679 nm as pump, the continuous-wave Tm channel WG laser generated 1.37 W at 1915-1923 nm with a record-high slope efficiency of 82.7% (with respect to the absorbed pump power), a threshold of only 17 mW and a spatially single-mode output with linear polarization. The WG propagation losses were 0.2 AE 0.3 dB/cm. Passive Q-switching of Tm channel WG lasers is achieved using Cr 2þ :ZnS and Cr 2þ :ZnSe saturable absorbers. With Cr 2þ :ZnS, record-short pulses of 2.6 ns/6.9 μJ at a repetition rate of 8.0 kHz were generated. The developed WGs are promising for compact GHz mode-locked lasers at~2 μm.

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Polarization anisotropy of thermal lens in Yb:KY(WO_4)_2 laser crystal under high-power diode pumping

et al. 2017

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Thermal lensing was studied in an N_g-cut monoclinic Yb:KY(WO₄)₂ (Yb:KYW) laser crystal under high-power diode pumping at ∼980 nm, for the two principal light polarizations, E||N_m and E||N_p. For both polarizations, the thermal lens (TL) was positive. It was found that operation of an Yb:KYW laser with the E||N_p polarization corresponds to a weaker TL that results in a better quality of the laser beam and superior power scaling capabilities. The sensitivity factors of the TL in this case were M=0.37 and 0.57 m^-1/W for the mg and pg principal meridional planes, respectively, and the astigmatism degree was as low as S/M=35% (for a pump beam radius of w_p=175 μm). The photoelastic terms, fractional heat loading, and generalized thermo-optic coefficients were evaluated.

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Photo-elastic effect, thermal lensing and depolarization ina-cut tetragonal laser crystals

Cited by 8 publications

References 34 publications

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

Ultrafast Laser Inscription and ∼2 μm Laser Operation of Y-Branch Splitters in Monoclinic Crystals

Watt-level ultrafast laser inscribed thulium waveguide lasers

Polarization anisotropy of thermal lens in Yb:KY(WO_4)_2 laser crystal under high-power diode pumping

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