A variety 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 and -30 dB stopband for 100-GHz OADM are 0.35 nm and 1.15 nm, respectively. The reflection path has an isolation 15 dB. In addition to the distinct cost advantage of ball lenses over the GRIN lenses, the ball-lens based OADMs also offer a significant simplification in packaging due to the intrinsic spherical symmetry of ball lenses. Optical designs and optics-related packaging issues are discussed in detail.
In this paper, we first review the working principle of grating-base wavelength division (de)multiplexers (WD(D)M) for optical networks. Then key device parameters for WDM multiplexers, including insertion loss, isolation, channel passband, wavelength accuracy, polarization-dependent loss and temperature sensitivity are provided to evaluate the performance for the devices. After that, issues regarding optical design of grating-based WD(D)Ms for commercial uses are addressed. Next, several grating-based WD(D)M structures are analyzed with the procedures to optimize design of grating-based wavelength division (de)multiplexers. Based on these designs and analyses, we give the procedures of optimal design of devices with experimental data.