5.1 Conclusion
A near-field pick-up head combined with nano-aperture and SIL/SSIL is achieved by MEMS technology. The self-alignment technique is adopted to overcome the misalignment between the SIL/SSIL and aperture component. By combining SIL/SSIL and aperture together, a small spot size with good light throughput can be obtained.
By SEM measurements, the maximum error of fabricated SIL/SSIL is less than 3% in comparison with the designed values. About aperture design, the diameter 103nm, 148nm, and 329nm of circular apertures and the dimensions 303nm×205nm and 223nm×105nm of C-shaped apertures are fabricated by FIB.
From the measurement results by the far-field equipment setup, the transmission of 15µm-diameter SIL is about 65.2% as well as SIL is verified to can really focus the incident light and reduce the spot size on the bottom of SIL. The 329nm-diameter aperture combined with 15um-diameter SIL can show 1.62 times enhancement of the light throughput in comparison with 329nm-diameter aperture alone. It is also found that since light in the SIL/SSIL can reduce its wavelength by a factor of n for SIL or n2 for SSIL, it passing through the aperture can decrease the light diffraction. Therefore, the performance of near-field pick up head integrated with SIL and aperture can be improved. Moreover, the aperture/SIL component can also smooth beam profile.
About measurement results of C-shaped aperture, the throughput of 300nm×200nm C-shaped aperture is about 1.081 times enhancement as compared with 329nm-diameter circular aperture , even can enhance the throughput by 14.325 times as compared with 148nm-diameter circular aperture. In comparison between C-shaped apertures, the
throughput of 223nm×105nm C-shaped aperture is 4.895 times larger than that of 303nm×205nm C-shaped aperture. This result matches the trend of simulation result but the enhancement effect is not as good as the simulation result. Then, the 303nm×205nm C-shaped aperture/15um-diameter SIL component also shows a 1.706 times enhancement of throughput as compared with 303nm×205nm C-shaped aperture alone, even shows a 24.438 times enhancement of throughput as compared with 148nm-diameter circular aperture alone.
About duration test, the profile of SIL is not damaged after 0.328mW of laser power destruction for 12hr.
5.2 Discussion
It is restricted to available measurement equipment. The far-field measurement system is used instead of near-field measurement system. Nevertheless, the spot size calibration of nano-aperture and enhancement effect of near-field can not be observed by far-field system. For this reason, we also try to use Near-Field Scanning optical microscope
（NSOM）to verify our researches in the future.
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