Light coupling setup
The setup (Fig. 4g) consists of a beam deflecting mirror (F), an X/Y stage (G) with a custom-made mount, a fixed-focus collimator (B) screwed into a rotation mount, an iris aperture (C), a 100 mm plano-convex lens (D), a 785 nm PM fibre pigtailed laser diode (A) with a typical output power of 7.5 mW, and a silicon CMOS camera to image the coupling (E).
The 785 nm laser diode is the source of incident light and the fibre is terminated with the fixed-focus collimator in a rotation mount, which is used for selection of s/p polarization. S polarization is chosen in this case. The iris aperture is used to control the beam diameter and, by extension, the range of incident angles introduced by the plano-convex lens used to focus the beam on the surface. A larger beam diameter and angular range broadens the range of in-plane propagation angles for the coupled modes. Finally, the beam is reflected onto the stage-mounted sample by a rotating deflection mirror.
The mirror and X/Y stage allow quick optimization of the input coupling conditions. The silicon CMOS cameras are used to capture the light coupling and splitting.Data published in this paper are available from the University of Southampton repository at Additional Information
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