Arbitrary Micro-nano Structures Fabricated By Interference Lithography And Its SERS

Radiation, transmit and receive are important natural phenomena. With the development of human society, the study of Light has not been stopped. In modern society, interaction between light and matter has been an important part of Light, especially the research on interaction between visible light wave and sub-wavelength structures is very meanful. The development of the Plasmonics expands the area of Light. Surface Plasmon Polaritions (SPP) are electromagnetic excitations propagating at the interface between a dielectric and a conductor, evanescently confined in the perpendicular direction.So fabrication the sub-wavelength structures is necessary. For visible light (400-700nm), the sub-wavelength is under 1μm, machining is hard to manufacture this kind structure. Now, the main method of manufacturing sub-wavelength structure including:focus iron beam lithography (FIB), electron beam lithography (EBL), light lithography and so on. While FIB and EBL is low efficiency and is hard to manufacture large area structure. Another method can resolve this problem-light lithography-including interference lithography and laser direct lithography.As the increasing of the interface electromagnetic field due to the adsorbed molecules’Raman Scattering signal is greatly enhances. This phenomenon is called Surface enhanced Raman spectrum (SERS).SERS is widely used in the study of the surface, surface state adsorption surface, biological molecules to the size of the interface orientation and configuration, conformational study, structural analysis, etc., can effective adsorption orientation analysis of compounds in the interface, the change of the adsorption state, interface information.There are two account for SERS, including physical explanation and chemistry explanation, and the main enhance is caused by local electromagnetic field enhance. The kind of electromagnetic field enhance is tie up to SPP.Our main points are listed as following:1. Using YG980 pulse laser to manufacture grating. As the pulse laser has high power, so this method can manufacture grating with less flash. And we use PDMS to copy the polymer grating as to metal grating.2. Using DMD to release laser direct lithography and multi-beam interference lithography. Laser direct lithography can manufacture all kinds of 2D pattern. DMD and prism can simplify the multi-beam interference lithography experimental device.3. Using DMD laser direct lithography to manufacture metal tapers with different angle. To study the relationship between angle and SERS.In this thesis, the innovation and highlights are listed as follows:1. As the conventional multi-bean interference lithography experimental device is hard to build. So we put forward a new method to resolve this problem. Using DMD to graduate some beams, there beams can be coupled into the multi-face prism to interference with each other. Then we can get the multi-beam interference pattern.2. In order to study the relationship between angle and SERS, we should to get the Raman Scattering spectrum of the different angle. So we use laser direct lithography to manufacture tapers with different angle. The we get the relationship:the smaller angle, the more enhancement of SERS and the enhancement was sensitive to the angle for acute angles but almost constant for angles greater than 90 degrees.