Ultrafast laser inscription of an integrated multimode-to-single-modes waveguide transition for astrophotonics

Astrophotonics is the application of photonic principles to astronomical instrumentation, in order to reduce cost, size, weight and complexity while increasing performance. In astrophotonics the “photonic lantern” (PL) [1–4] is a remarkable photonic device which efficiently couples light between a multimode (MM) optical fibre and a set of degenerate single modes (SMs) which are guided by the cores of either individual SM fibres [1–3] or a multicore optical fibre [4]. If the SMs produced by the PL are arranged into a linear array [5], the PL facilitates the efficient collection of light from a telescope using a MM fibre and the low-loss reformatting of this light into a near diffraction limited input (in one axis) for a spectrometer [6].