Microlens at the end of single mode fibers for thermal writing in optical data storage
碩士 === 國立交通大學 === 光電工程所 === 89 === Most of commercial optical disks use the substrate-incidence recording which has restrictions in using high numerical aperture objective lens to achieve high recording density. Besides, the objective lens is heavy, thus difficult to further reduce the ma...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2001
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| Online Access: | http://ndltd.ncl.edu.tw/handle/78982409547359877267 |
| Summary: | 碩士 === 國立交通大學 === 光電工程所 === 89 === Most of commercial optical disks use the substrate-incidence recording which has restrictions in using high numerical aperture objective lens to achieve high recording density. Besides, the objective lens is heavy, thus difficult to further reduce the mass of optical head and improve the seek time. The microlens at the end of single mode fiber is proposed to take the place of the conventional objective lens in thermal writing on both magnetic-optical and phase-change disks for its light weight and handiness.
Laser beam is coupled into the single mode fiber with an objective lens, then focus on a disk due to the microlens at the end of single mode fiber. The optical calculation of the microlens suggests that the length of silica rod and the radius of the microlens have to be properly chosen in order to obtain suitable spot size of 0.5μm and working distance of 200μm. Due to the surface tension, we can fabricate a microlens at the end of the fiber by using the arc discharge of fusing machine. The minimum spot sizes of 0.6 and 0.5um of the microlenses at the end of single mode fiber at a 660nm wavelength were demonstrated and the coupling efficiency was 50%. This enables to write continuous marks of 1.8um on commercial disk.
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