Testability of Erbium Doped Fiber Amplifiers: An Approach Towards Yield Improvement

Abstract

Erbium Doped Fiber Amplifiers (EDFAs) are extensively used in Dense Wavelength Division Multiplexing (DWDM) technology for long haul optical transmission networks. The manufacturing of optoelectronic products has been gradually transferred from Original Equipment Manufacturers (OEMs) to the Electronics Manufacturing Service (EMS) providers. Operator dependency and the lack of automation increase the cycle time in optoelectronics manufacturing. Manufacturing difficulties and lower yield reduce the throughput. Consequently, identifying and implementing activities to improve yield becomes crucial for an EMS provider to survive in a medium-to-high volume environment. During the manufacturing processes, several tests are conducted to calibrate the EDFA at room temperature and temperature extremes. Critical parameters such as gain, flatness, and the noise figure are monitored at multiple stages. Failures (or non-conformities) observed in any of these parameters at any stage results in a reduced first pass yield. In this paper, several aspects of testing an EDFA and the failure modes at various stages, which result in lower yields, have been discussed. Root cause analysis and the corrective actions taken to significantly improve the first pass yield are presented. Relationships between some of the critical parameters have been discussed. Finally, guidelines for yield improvement are delineated. The results are based upon studies conducted on an EDFA, which is manufactured by the facility where this research was conducted.