Recently, spectral measurement becomes an important tool in astronomy to find exoplanets etc. The fibers are used
to transfer light from the focal plate to spectrometers. To get high-resolution spectrum, the input slits of the
spectrometers should be as narrow as possible. In opposite, the light spots from the fibers are circle, which diameters are
clearly wider than the width of the spectrometer slits. To reduce the energy loss of the fiber-guide star light, many kinds
of image slicers were designed and fabricated to transform light spot from circle to linear. Some different setup of fiber
slicers are introduced by different research groups around the world. The photonic lanterns are candidates of fiber slicers.
Photonic lantern includes three parts: inserted fibers, preform or tubing, taped part of the preform or tubing. Usually the
optical fields concentrate in the former-core area, so the light spots are not uniform from the tapered end of the lantern.
We designed, fabricated and tested a special kind of photonic lantern. The special fibers consist polymer cladding and
doped high-index core. The polymer cladding could be easily removed using acetone bath, while the fiber core remains
in good condition. We inserted the pure high-index cores into a pure silica tubing and tapered it. During the tapering
process, the gaps between the inserted fibers disappeared. Finally we can get a uniform tapered multimode fiber end. The
simulation results show that the longer the taper is, the lower the loss is. The shape of the taper should be controlled
carefully. A large-zone moving-flame taper machine was fabricated to make the special photonic lantern. Three samples
of photonic lanterns were fabricated and tested. The lanterns with cladding-removable fibers guide light uniform in the
tapered ends that means these lanterns could collect more light from those ends.