Fig. 1: Concept and system.
From: Dynamic control and manipulation of near-fields using direct feedback
a Illustration of the Nonlinear Nearfield Optical Microscope (NNOM) used for mapping wavefront-controlled near-field patterns. SLM – Spatial light modulator. OPO – Optical parametric oscillator. DM – dichroic mirror. QWP – Quarter waveplate. The objective used to focus the OPO signal on the sample has NA of 0.42 and magnification of x 20, while the objective used for imaging has NA of 0.9 and magnification of x 100. b Linearly-ascending radially symmetric phase mask stored on the SLM for producing a ring-shape beam. c SEM image of the sample: a circularly symmetric grating carved in a 180 nm thick gold layer. d Optical image showing the grating illuminated by the equal-phase ring at 1030 nm wavelength. e Real-time mapping of the excited near-field pattern at 667 nm using NNOM. The inset shows a zoom-in on the resultant 0th order Bessel mode
