| 研究実績の概要 |
Optimal concentrations of Er3+ and Yb3+ were investigated based on quantum efficiency measurements in KY3F10, NaYF4, LiYF4 nano- and micro-crystals. The highest quantum efficiency about 14% in the Er3+ and Yb3+ co-doped KY3F10 nanocrystals was achieved. The addition of third type of lanthanide ions (Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Dy3+, Ho3+, and Tm3+) did not help to enhance quantum efficiencies due to the quenching effect caused by the energy transfer processes between their low energy levels.
The technique of fabricating laser-induced self-written waveguide was improved. The Er3+ and Yb3+ co-doped KY3F10 nanocrystals were well dispersed into monomer for fabricating waveguides as gain media. The waveguides doped with nanocrystals fabricated via laser-induced self-written technique were connected with single mode fibers on both sides. The volume fraction of nanocrystals was designed according to the simulation of Rayleigh scattering. Amplified spontaneous emission was observed in the nanocrystals doped waveguide with the length of about 7 mm. The optical gain in the C-band at 1539 nm was obtained about 6 dB under excitation of 400 mW 976 nm laser.
The “X” type of waveguide structure composed by two self-written waveguides was successfully fabricated by precisely controlling the laser propagation path. Complex structures that two waveguides grew without intersection were also successfully fabricated. The interaction of lights in two approaches in the device based on the “X” type of structure was investigated.
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