Tight focusing of circularly polarized beam over high NA lens axicon with a diffractive optical element |
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Authors: | P Suresh C Mariyal K Gokulakrishnan KB Rajesh TVS Pillai |
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Institution: | 1. Department of ECE, National College of Engineering, Tirunelveli 627151, Tamilnadu, India;2. University Department, Regional Center, Anna University, Tirunelveli Region, Tirunelveli 627007, Tamilnadu, India;3. Department of Physics, Chikkanna Government Arts College, Tiruppur 641602, Tamilnadu, India;4. Department of Physics, University College of Engineering, Nagercoil 629002, Tamilnadu, India |
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Abstract: | We propose to use diffractive optical element in combination with high NA lens axicon to achieve a high depth of focus when illuminated by a circularly polarized beam. With this kind of system, the focal depth is increased to 12.816λ and the magnetic spot size is reduced to 0.3764λ. However, in the conventional lens with same NA, the FWHM of the magnetic spot is found to be 0.4308λ and its corresponding magnetization depth is only 0.888λ. The author expects that such a high focal depth strong longitudinal magnetic field with large magnetization depth can be widely used in high density magneto optic recording, laser machining, laser cutting and the scanning near-field magnetic microscope. |
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Keywords: | Diffractive optical element Lens axicon Circularly polarized beam Ultrafast magneto-optic recording Focal depth |
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