Publications by authors named "Mio Koyama"

4 Publications

  • Page 1 of 1

Quadratic nonlinear optical properties of the organic N-benzyl-2-methyl-4-nitroaniline (BNA) biaxial crystal.

Opt Lett 2018 Apr;43(8):1818-1821

We performed the direct measurement of second harmonic generation and sum frequency generation phase-matching directions in the organic N-benzyl-2-methyl-4-nitroaniline crystal over its visible and near-infrared transparency range. The fit of these data allowed us to refine the Sellmeier equations of the three principal refractive indices in this range. With these equations, we improved the calculated tuning curves of terahertz emission from a phase-matched difference frequency process. We also determined the absolute magnitude of the d nonlinear coefficient.
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http://dx.doi.org/10.1364/OL.43.001818DOI Listing
April 2018

Ultraviolet vortex generation using periodically bonded β-BaB₂O₄ device.

Opt Express 2014 Jun;22(11):12829-35

This paper describes the first demonstration of ultraviolet (266nm) vortex generation using the combination of a frequency-doubled nanosecond green laser, a spiral phase plate, and a periodically bonded β-BaB2O4 device. For a laser pumping energy of 9.1 mJ, an ultraviolet vortex energy of 1.24 mJ was obtained, corresponding to a conversion efficiency of 13.7%.
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http://dx.doi.org/10.1364/OE.22.012829DOI Listing
June 2014

Nanosecond vortex laser pulses with millijoule pulse energies from a Yb-doped double-clad fiber power amplifier.

Opt Express 2011 Jul;19(15):14420-5

Graduate School of Advanced Integration Science, Chiba University,1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.

Nanosecond vortex pulses were generated using a stressed, large-mode-area, Yb-doped, fiber amplifier with an off-axis coupling technique for the first time. A pulse energy of 0.83 mJ (corresponding to a peak power of 59 kW) was achieved at a pump power of 25.7 W. The optical-optical efficiency was measured to be 31%. The millijoule nanosecond vortex pulses will be potentially applied to novel material processing, such as metal microneedle fabrication.
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http://dx.doi.org/10.1364/OE.19.014420DOI Listing
July 2011

Power scaling of a picosecond vortex laser based on a stressed Yb-doped fiber amplifier.

Opt Express 2011 Jan;19(2):994-9

Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba, Japan.

Power scaling of a picosecond vortex laser based on a stressed Yb-doped fiber amplifier is analyzed. An output power of 25 W was obtained for 53 W of pumping, with a peak power of 37 kW. Frequency doubling of the vortex output was demonstrated using a nonlinear PPSLT crystal. A second-harmonic output power of up to 1.5 W was measured at a fundamental power of 11.2 W.
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http://dx.doi.org/10.1364/OE.19.000994DOI Listing
January 2011
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