Large Area Multimode Photonic Band-Gap Propagation in Photonic Liquid-Crystal Fiber

In this letter, we report a new very large mode area multimode photonic band-gap (PBG) propagation in a solid core photonic crystal fiber (PCF) filled with a liquid crystal (LC). The host fiber was designed with a 50- μm core diameter to optimize the light coupling from standard multimode fibers. After filling it with LCs, multimode selective propagation was observed and it was possible to tune the bands with temperature. The mode field was well localized in the core area and compared to our previous works, a much smaller percentage of optical power penetrates the LC-filled holes. Consequently, the scattering loss is reduced, allowing for lower insertion losses. Attenuation was measured by the cut-back technique and for one of the band gaps it was 0.16 dB/cm, which, to the best of our knowledge, has been the lowest level of attenuation reported so far in PBG-guiding LC-filled PCFs.