New generation of photonic lanterns for mid-IR astronomy

We report the fabrication and characterization of prototype femtosecond-laser direct-written integrated photonic lanterns for operation in the mid-infrared (mid-IR). The devices were inscribed inside the bulk of a commercial gallium lanthanum sulphide (GLS) chalcogenide glass substrate and the characterization was performed using monochromatic light with a wavelength of 3.39 μm. We demonstrate that these proof-of-concept devices are capable of coupling specific multimode states of light into an array of single-modes, and vice-versa, with low-loss. In the future, instruments that utilize the single-moded output of such components may find applications in areas such as heterodyne spectroscopy, interferometry and remote sensing.