Browsing by Author "Lee, Cheng-Yeh"

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Developing a microspectrophotometer to measure the dependence of broadband refractive indices on Ge-doped concentrations in GRIN rods
(2015-11-30)
Weng, Chun-Jen
;
Hsu, Ken-Yuh
;
Lee, Cheng-Yeh
;
Chen, Yung-Fu
;
電子物理學系
A confocal microspectrophotometer is utilized to scan the surface reflectivities of a polished gradient-index (GRIN) rod in the range of 400 to 900 nm. The pure fused silica is used to be a reference standard for deducing the absolute reflectivities of the Ge-doped core. Then, multi-wavelength refractive index profiles of the Ge-doped core can be further determined based on the Fresnel equation. Moreover, this work shows a connection between the material dispersion of the GRIN rod and the Gedoped concentrations measured by an energy dispersive spectrometer. Finally, the dependence of the refractive index of the Ge-doped core on the doping concentrations at a certain wavelength can be easily expressed as a linear form. (c) 2015 Optical Society of America
Generation of Higher Order Vortex Beams From a YVO4/Nd:YVO4 Self-Raman Laser via Off-Axis Pumping With Mode Converter
(2015-01-01)
Lee, Cheng-Yeh
;
Chang, Chuan-Ching
;
Cho, Chun-Yu
;
Tuan, Pi-Hui
;
Chen, Yung-Fu
The generation of high-order Hermite-Gaussian (HG) beams at the Stokes wavelength in a YVO4/Nd:YVO4 self-Raman laser with off-axis pumping is demonstrated. The high-order vortex beams at the Stokes field are successfully created by transforming these HG modes via an extra-cavity mode converter. The stimulated Raman scattering (SRS) threshold pump power for the diode-end-pumped laser is theoretically analyzed to verify the feasibility of generating high-order HG modes by off-axis pumping. At a pump power of 18.6 W, the SRS output powers can be higher than 1.0 W for the HG modes from TEM0,0 to TEM3,0. Under the same pump power, the maximum order can be up to TEM28,0.
Optical vortex pumped solid-state Raman laser
(2017-01-01)
Nishigata, Yoshihiro
;
Lee, Cheng-Yeh
;
Miyamoto, Yuji
;
Miyamoto, Katsuhiko
;
Chen, Yung-Fu
A vortex Raman laser pumped by the second-order optical vortex mode was demonstrated. The first-and the second-Stokes waves that lased at the first-order optical vortex mode were generated. Considering the spatial intensity overlap between the pump and the first-Stokes beam, and between the first-and second-Stokes beams, the generation of a topological charge of 1 in the Stokes fields could be theoretically predicted.