Figure 7: Shaping of output modes by azimuthally independent modulations.
From: Exploiting multimode waveguides for pure fibre-based imaging
(a) Conservation of the propagation constant: light coupled into the fibre with a specific propagation constant kz will leave the fibre with this quantity unchanged. (b) Holographic modulation to convert a sample mode into a 'bottle' beam. (c) Annular filtering of the sample mode leads to generation of a Bessel beam. (d) Quadratic radial phase modulation (defocus) shifts the sample mode axially. Panels f, h and i are azimuthally averaged projections of three-dimensional data stacks obtained from a series of CCD frames (e,g) obtained at different axial distances behind the fibre. For all the panels e–i, the vertical scale bars correspond to distance of 10 μm while horizontal ones correspond to 50 μm.
