Modelling the sharp focusing of laser light

Click here to load reader

  • date post

    10-Jan-2016
  • Category

    Documents

  • view

    27
  • download

    0

Embed Size (px)

description

Modelling the sharp focusing of laser light. Sergey Stafeev Samara State Aerospace University Image Processing System Institute REC -14 , Samara. Voronezh, 2010. Introduction. Decreasing the focal spot size is critical in lithography, optical memory and micromanipulation - PowerPoint PPT Presentation

Transcript of Modelling the sharp focusing of laser light

  • Modelling the sharp focusing of laser lightVoronezh, 2010Sergey StafeevSamara State Aerospace University Image Processing System Institute REC-14, Samara

  • IntroductionDecreasing the focal spot size is critical in lithography, optical memory and micromanipulationSharp focusing is a reaching a minimal focal spot size beyond the diffraction limits.

    Recently plasmons with FWHM = 0.35 [Opt.Lett. - 2009. - Vol.34, no.8. - P.1180-1182], FWHM = 0.4 [Opt. Lett. - 2009. - vol.34, no12. - p.1867-1869] had been obtained. In this research we used two types of axicons: refractive and diffractive which were illuminated by radially polarized light

  • Radial-FDTDFDTD = finite difference time domainThis method involves the numerical solution of Maxwell's equations in cylindrical coordinate system We used a modification for a radially polarized light (R-FDTD)There are three equations with three components Er, Ez and H(1)(2)

  • Refractive microaxiconFocusing of radially-polarized mode R-TEM01 (3)

    using refractive (conical) microaxicon Radial section of a conical glass (n=1.5) microaxicon of radius R = 7 m and height h = 6 mThe (absolute value of) radial component of the electric field strength of the mode R-TEM01FWHM=0.30HMA=0.0712

  • Instantaneous distributions of the amplitude Er and Ez for diffraction of the R-TEM01 laser mode by the refractive microaxiconThe Intensity and FWHM of the focal spot as a function of axicons height ErEzRefractive microaxicon: 3D modellingthe intensity distribution in focal planethe intensity distribution along axicon axis

  • Binary microaxiconFWHM = 0.39 HMA= 0.1192binary axicon with step height 633nm, period 1.48um, index of refraction n = 1.5the intensity distribution along axicon axisthe intensity distribution in focal plane (on the axicons surface)Focusing of radially-polarized mode R-TEM01 using binary microaxicon

  • Manufacture and experimentThree diffractive binary axicons of periods 4 m, 6 m, and 8 m and height 500nm were fabricated on silica substrate (n=1.46) using a laser writing system CLWS-200 (bought with CRDF money) and plasmo-chemical etching.Diameter of the focal spot in the near-zone (z
  • ConclusionsWe have numerical shown that when illuminating a conical glass microaxicon of base radius 7 m and height 6 m by a radially polarized laser mode R-TEM01 of wavelength =1 m, in the close proximity (20 nm apart) to the cone apex, we obtain a sharp focus of transverse diameter at half-intensity FWHM=0.30 and axial spot size at half-intensity FWHMz=0.12. The focal spot area at half-intensity equals HMA=0.0712.Three diffractive binary axicons of periods 4 m, 6 m, and 8 m and height 500nm were fabricated on silica substrate (n=1.46) using a laser writing system CLWS-200 (bought with CRDF money) and plasmo-chemical etching.Diameter of the focal spot in the near-zone (z