Technique of microball lens formation for efficient optical coupling

A batch-fabricated microball lens array not only provides accurate coupling distances but also replaces traditional components such as aspheric lenses and expensive graded-index lenses without sacrificing performance and reduces assembly cost. The results of extensive experiments show a critical aspect ratio of similar to0.3. That is, when the aspect ratio is larger than 0.3, the final shape of a reflowed lens changes to that of a microball rather than of a mushroom. Using a laser with a 633-nm wavelength yields an optimum coupling distance of similar to8 mum with an insertion loss below - 1.3 dB (coupling efficiency, similar to73%). (C) 2004 Optical Society of America.