Direct Photolithography on Optical Fiber End

New photolithography techniques have been developed for fabricating an arbitrary structure on the optical fiber end. One technique consists of preparing a uniform resist film on the optical fiber end. The area of the fiber end is too small to apply the normal spin coating method. The surface tension of the resist strongly disturbs the film uniformity. The spray coating technique can be used to prepare a thin uniform resist film reducing the effect of the surface tension. Another technique is for transferring the arbitrary pattern aligned to the fiber core. The mask including the arbitrary pattern and the alignment guide hole is prepared using the self-aligning method. These techniques are promising for fabricating the microlens which improves the coupling efficiency between the laser diode and the fiber. The effect of the fabricated lens on the optical fiber end is confirmed.