fig2: 9 x rows 1. Topological Charge, m 2. delta z - experiment - no OAM 3. positive error in 2 4. negative error in 2 5. delta z - experiment - OAM 6. positive error in 5 7. negative error in 5 8. theoretical prediction - no OAM 9. theoretical prediction - OAM fig3a: Same data as fig3b fig3b: 6 x rows 1. Topological Charge, m 2. Delta delta z - experiment 3. positive error in 2 4. negative error in 2 5. theoretical prediction - v_g theory 6. theoretical prediction - ray tracing raw_data: HOM dip measurements used to obtain the figures shown in the paper. Data was obtained in 2 sets, each has a sub-folder for each scan of the HOM dip. The files in each sub-directory relate to the mask that was applied to the Spatial Light Modulators. display on first SLM in beam path -- display on second SLM dip_0. grating + lens -- grating + lens dip_1. grating only -- grating only dip_2. grating + lens + ring aperture for l=1 -- grating + lens dip_3. grating + lens + ring aperture for l=1 + azimuthal phase for l=1 -- grating + lens + azimuthal phase for l=1 dip_4. grating + lens + ring aperture for l=2 -- grating + lens dip_5. grating + lens + ring aperture for l=2 + azimuthal phase for l=2 -- grating + lens + azimuthal phase for l=2 dip_6. grating + lens + ring aperture for l=3 -- grating + lens dip_7. grating + lens + ring aperture for l=3 + azimuthal phase for l=3 -- grating + lens + azimuthal phase for l=1 dip_8. grating + lens + ring aperture for l=4 -- grating + lens dip_9. grating + lens + ring aperture for l=4 + azimuthal phase for l=4 -- grating + lens + azimuthal phase for l=4 dip_10. grating + lens + ring aperture for l=5 -- grating + lens dip_11. grating + lens + ring aperture for l=5 + azimuthal phase for l=5 -- grating + lens + azimuthal phase for l=5 dip_12. grating + lens + ring aperture for l=6 -- grating + lens dip_13. grating + lens + ring aperture for l=6 + azimuthal phase for l=6 -- grating + lens + azimuthal phase for l=6 dip_14. grating + lens + ring aperture for l=7 -- grating + lens dip_15. grating + lens + ring aperture for l=7 + azimuthal phase for l=7 -- grating + lens + azimuthal phase for l=7 dip_16. grating + lens + ring aperture for l=8 -- grating + lens dip_17. grating + lens + ring aperture for l=8 + azimuthal phase for l=8 -- grating + lens + azimuthal phase for l=8