title: Technique of microball lens formation for efficient optical coupling.
abstract: 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 approximately 0.3. 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 approximately 8 microm with an insertion loss below -1.3 dB (coupling efficiency, approximately 73%).
authors.affiliation: Department of Mechanical and Electro-Mechanical Engineering and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaoshiung 804, Taiwan. panct@mail.nsysu.edu.tw
authors.forename: Cheng-Tang
authors.initials: CT
authors.lastname: Pan
authors.forename: Chi-Hui
authors.initials: CH
authors.lastname: Chien
authors.forename: Chi-Chang
authors.initials: CC
authors.lastname: Hsieh