Packaging of a polarization independent optical isolator

The authors describe the design, packaging and performance of a polarization-independent, pigtailed optical isolator. The design consists of two birefringent wedges sandwiching a Faraday rotator crystal. This sandwich is bonded into the centre of a cylindrical SmCo magnet. The isolator is packaged in a metallic package consisting of stainless steel and Kovar. All critical interfaces are either soldered, resistance-welded, or laser-welded. The resulting package is shown to be both mechanically and environmentally stable. Typical performance values are: insertion loss, nominally 1.7 dB, peak isolations >40 dB, and return loss > 60 dB. Principal applications of the isolator include direct attachment to laser packages, semiconductor amplifier packages, and fiber amplifiers