NSOM近场光学ppt课件

1、NSOM 近场光学,界面和倏逝场,透射和反射系数,近场光学,近场光学的历史,1928 AD E. H. Synge ( England ),1973 AD Ash optical methods are disturbing the optical response).,xyz piezo,Feedback,Impedance detector,Electrodes,Piezo actuator,Aperture SNOM,Aperture SNOM,Illumination,Collection,Illumination collection,Reflection collection,Tr

2、ansmission illumination,Transmission collection,Operational modes,Typical set up,Aperture SNOM,Monochromator,SNOM tips,Aperture SNOM,Optical fiber,SNOM tips Calculation of the distribution of electric field as a function of the tip geometry,Aperture SNOM,Source: InAs Qdot Point like source l/40 belo

3、w the surface,SNOM tips - pulling,Aperture SNOM,Core,Cladding,Metal coating,SNOM tips - etching,Aperture SNOM,Core,Light propagation,Cladding,Metal coating,Holes are dug by various methods: The best results are obtained by FIB,NSOM 应用的优点,与传统光学显微镜比较,衍射极限的突破 大幅降低设备成本,理想透镜可分辨的最小距离 D,D =,0.61,NA,：入射光波长

4、NA：透镜的数值孔径,与电子扫描式显微镜 ( AFM、STM)比较,非破坏性测量 可侦测到真实的表面 ( Real Surface Measurement ),样品不需繁复的制备手续,无需在真空下检测,具有其他光学性质的优点,应 用,近场光学原理除了 应用于近场光学显微镜、作为纳米尺寸的局部光学强度与材料的光学特性等测量用外，由于此技术同时具有纳米尺寸加工与曝光的能力，故还可用于制作单电子晶体管、量子阱等纳米元件，以及应用于更高密度的存储器上。,optical quantum corral,Aperture SNOM,The experiment: Testing the subwavelke

5、nght modulation induced on the local density of states of the optical modes by the fabrication of nanometric opticla corrals Substrate ITO Modulators 100nm100nm50nm gold particles deposited by e-beam lithography,To test the real LDOS the tip should act as a perfetct dipole at a nanometric distance f

6、rom the surface. Real tips always pertirb the LDOS and what is measured is the combined LDOS of the sample and the tip!,optical quantum corral,Light Polarization control Elliptical mirros that selects only the near field radiation (propagating radiation is not allowed in the “forbidden light region with qqc The signal is 0 only closo to the sample,optical quantum corral,Teorical optical LDOS in x, y and z direction,optical quantum corral,Near field results in trasmission. Best results obtained with a gold coated tip without apertures (the tip At the tip the polari