2013 Fiscal Year Final Research Report
Waveguide visible lasers with tailored clad shapes directly drawn by femtosecond laser pulses
| Project/Area Number |
24656055
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Keio University |
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Principal Investigator |
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Keywords | レーザ描画導波路 / 導波路レーザ / 可視域レーザ / フェムト秒レーザ加工 / 時空間集光 |
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| Research Abstract |
When persistent refractive index change induced in the inside of transparent bulk materials by multi-photon absorption at intense femtosecond laser irradiation is used for a waveguide core, non-uniform refractive index change causes propagation loss and thus this scheme is not applicable for efficient waveguide laser fabrication. Since fluoride glasses exhibit negative refractive index change at femtosecond laser irradiation, we proposed direct clad drawing with femtosecond laser pulses. A novel simultaneous spatial and temporal focusing (SSTF) scheme was employed to confine laser excitation into smaller volumes especially along the depth direction. Clad drawn waveguides fabricated in Pr:ZBLAN glass successfully worked as a laser waveguide with a transmission loss of 0.58dB/m at 633 nm. However, since the refractive index change was smaller than we expected, the present waveguide NA was limited to 0.015.
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