Analysis of Output Light Field of the Photonic Lantern with Cladding-Removable Fibers

Optical fiber and optical fiber devices have been widely used in different fields. Fiber image slicer can effectively improve the optical efficiency of high-resolution stellar spectrometer. In order to further improve the light transmission efficiency of the fiber image slicer, a special kind of photonic lantern image slicer was designed, fabricated and tested. 7 cladding-removed fibers with high-refractive-index cores were inserted into a pure silica tubing. The whole structure was tapered to fabricate a photonic lantern. In the tapered end, the refractive-index distribution of the new waveguide is similar to a normal step-index multimode fibers. Two theories of slowly varying waveguide and super mode coupling theory are used to analyze the output light field of the photonic lantern. The simulation results show that, when the light just incident one fiber, all the output light field have the quasi Gauss distribution. We made a photonic lantern and tested its transmission characteristics. A white light source was used as the light source to measure the output light field of the photonic lantern. The test results show that all the output light field have the quasi Gauss distribution.