Ball-lens based optical add-drop multiplexers: design and implementation

Two types of ball-lens based optical add-drop multiplexers (OADMs) are designed and implemented. Insertion losses as low as 0.5 to 0.6 dB for the reflection light-path, and 1.2 to 1.5 dB for the transmission light-path are demonstrated. The 0.5-dB passband is 44% to 50% of the channel spacing and 30% to 33% of the -30-dB stopband for 100- and 200-GHz OADMs. The reflection path has an isolation of 15 dB. In addition to the distinct cost advantage of ball lenses over gradient index lenses, the ball-lens based OADMs also offer a significant simplification in packaging. The external diameter of the package is 5.5 mm.