Description
Hybrid mode-selective photonic lanterns (HMSPL) provide a route to combine efficient multimode coupling with mode-specific single-mode extraction, which is attractive for astrophotonic instrumentation, wavefront sensing, and spatial-mode manipulation[1]. We present two six-core HMSPL designs targeting preferential selection of the LP01 and LP02 modes using circular packing [2].
The LP01-selective PL uses a specialty fibre to improve adiabatic coupling of the centre core into the fundamental mode. In contrast, the LP02-selective lantern uses a step-index central fibre, chosen to support a modal evolution better matched to the radial structure of the LP02 mode. By changing the geometry profile of only the central element while keeping the same circular-packing geometry, the two lanterns isolate the role of core profile in hybrid mode selectivity.
The devices are designed so that the selected mode is preferentially routed to the central single-mode output, while the remaining supported modes are distributed among the surrounding outputs rather than being fully mode selective. This hybrid architecture relaxes fabrication tolerances compared with fully mode-selective lanterns, while preserving a dedicated output channel for the target mode. The approach is particularly relevant to photonic-lantern focal-plane wavefront sensing, where a science channel may be extracted from one mode while the residual modal distribution remains available for sensing or diagnostic information. These two designs demonstrate a compact and scalable method for engineering LP01 and LP02 selectivity using standard fibre components, controlled circular packing, and targeted central-fibre index design.
[1] B. Norris et al., “Optimal broadband starlight injection into a single-mode fibre with integrated photonic wavefront sensing,” Optics Express, vol. 30, pp. 34908–34923, 2022.
[2] N. K. Fontaine, R. Ryf, J. Bland-Hawthorn, and S. G. Leon-Saval, “Geometric requirements for photonic lanterns in space division multiplexing,” Optics Express, vol. 20, pp. 27123–27132, 2012.
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