Study of the integration process between the nano-aperture and solid immersion lens for near-field recording pick-up head
|關鍵字:||近場光學;奈米孔;固態浸沒透鏡;自我對準;微機電系統;C形孔;聚焦離子束;熱回流;near-field potics;nano-aperture;solid immersion lens;self-alignment;MEMS;C-shaped aperture;focused ion beam;thermal reflow|
For near-field recording systems, Aperture and Solid Immersion Lens（SIL） are two popular techniques to overcome light diffraction limit and reduce spot size. In aperture systems, seeing that light spot size is directly determined by aperture size, aperture systems can provide an ultra-high resolution by reducing the aperture size to nano-scale. However, nano-aperture suffers from low power throughput which results in the recording speed unable to be promoted. SIL systems, while can providing a smaller spot size than obtained in conventional optical recording systems with still maintaining high optical throughput, do not have the resolution observed from aperture probe systems. According to previous researches, nano-aperture combined with SIL/SSIL can improve the throughput owing to greater power densities at the aperture. However, the misalignment between the SIL/SSIL and nano-aperture always occurred in assembling or bonding step. How to align the nano-aperture and SIL/SSIL together precisely has not proposed yet. In this research, the purpose is concentrated on combination of SIL/SSIL and nano-aperture by Nano/Micro Electro-Mechanical Systems（N/MEMS） technology, where nano-aperture is fabricated with Focused Ion Beam（FIB）system and SIL /SSIL are formed by thermal reflowing process. In order to overcome the misalignment between SIL/SSIL and nano-aperture, a self-alignment technique based on self-modulation by surface tension during thermal reflowing process is proposed. About aperture designs, the influence of varied shapes of apertures at optical throughput is also studied. Here, circular apertures and C-shaped apertures are introduced. In fabrication results, SIL and SSIL are fabricated and the maximum error is less than 3% in comparison with the designed values. About nano-aperture, the diameter 103nm, 148nm, and 329nm of circular aperture and the dimensions 303nm×205nm and 223nm×105nm of C-shaped apertures are fabricated. The feasibility of self-alignment technique between SIL/SSIL and nano-aperture proposed in this research is also verified by Scanning Electron microscope（SEM）. From the measurement results of far-field system, the 15μm-diameter SIL/329nm-diameter circular aperture component has 1.68 times enhancement of throughput compared with 329nm-diameter aperture alone. This result shows that SIL can really enhance the light throughput of nano-aperture and the feasibility of self-alignment technique between SIL and nano-aperture is further verified. About measurement results of C-shaped apertures, the throughput of 303nm×205nm C-shaped aperture alone is 14.325 times larger than that of 148nm-diameter circular aperture alone, while maintaining a comparable near-field spot size. Even the throughput of 303nm×205nm C-shaped aperture/15μm-diameter SIL component can be enhanced by 24.438 times as compared with 148nm-diameter circular aperture alone. This result indicates that combination of SIL and C-shaped aperture can really greatly enhance the performance of near-field pick-up head.
|Appears in Collections:||Thesis|
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