In this work, the finite difference time domain (FDTD) method is used to optimize the multi-pixel sampling approach, in order to achieve ultra-high spatial resolution (∼ λ/110) in the near-field region. The optimization is performed based on the optical pump pulse wavelength, the thickness of the silicon modulator, and the size of the aperture in the projected pattern. To the best of our knowledge, this is the first time that the FDTD method has been used to improve near-field resolution. In addition, we consider the effect of pump wavelength on near field imaging resolution for the first time.

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The structural, electronic, and magnetic properties of MnAs crystal are studied. The WIEN2k code which uses a full-potential LAPW program based on density functional theory with GGA is used for the calculations. At first, the total energy of a MnAs crystal in different lattices is calculated and the corresponding - diagram is drawn for two different structures of MnAs. The effect of pressuring this crystal is determined. The calculations confirm that, MnAs has the NiAs-type structure at ambient pressure but transforms into the zinc-blend structure of a specific pressure value. Also, the electric field gradient (EFG) and hyperfine field (HFF) at the nuclear site of Mn and As are calculated. Finally, the effect of pressure on EFG and HFF is studied.