Evaluating the reliability of optical connectors

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Evaluating the reliability of optical connectors 7 The optical characteristics of the optical connectors reviewed for this study were automatically measured during the High Temperature Storage Test (Damp Heat) (at 85°C and 85 percent relative humidity for 1000 hours) and the Temperature Cycling Test (at 85°C / -40°C for 500 cycles of one hour each). We obtained the following results. (1)No changes occurred in optical characteristics, but pistoning increased in the connectors. (2)Increased pistoning of the ferrule tips was observed in both the Temperature Cycling Test and the High Temperature Storage Test (Damp Heat), but the major changes occurred in the Temperature Cycling Test. (3)The post-test condition of the ferrule tips after testing at 85°C and 85 percent relative humidity for 2000 hours exhibited flattening distortion. This result could indicate that the actual pistoning was greater than the calculated amount. 8 Conclusion Topics for future discussion Many aspects of the relationship between pistoning and optical characteristics have yet to be confirmed, and topics such as manufacturing conditions also require research. [Terminology] *1.Telcordia The breakup of the American communications giant AT&T (Bell Telephone) created seven regional telephone providers (the so-called "Baby Bells") and established a research and development company initially called Bellcore. Later, when this subsidiary was sold to a company unrelated to the original Bell, the company became known as Telcordia Technologies. In the field of communications in the U.S., the Telcordia standards are widely referenced as the baseline standards for this field. *2.SC connectors, and *3. FC connectors Both of these optical connectors are zirconia ferrule (refer to Fig.2 above) connectors developed in Japan that are widely used throughout the world. The stationary part of the SC connector is made of plastic, and can be connected by merely being pressed on. The stationary part of the FC connector, though, is made of metal and must be attached with screws. *4.Insertion loss The transmission loss occurring when light passes through the part. This value compares the insertion light with the outgoing light, and is expressed in decibels. *5.Return loss This value compares the insertion light power and the reflected light power of the reflected light returning inside the part. This value is expressed in decibels. - 10 - Espec Technology Report No20
Evaluating the reliability of optical connectors *6. PDL (Polarization Dependent Loss) The PDL value measures the change occurring in insertion loss caused by polarization. Polarization is a condition of deviation in the vibrational direction of light. *7. Single mode Single mode is a condition which provides light with a single pathway of propagation. This mode contrasts with multi-mode, which consists of multiple pathways of light propagation. Due to the mode-dispersed loss occurring in multi-mode, single mode is used for long-distance transmission. *8. Curvature radius The length (in mm) of the radius of a circle from a circumference projected from a curved surface. *9. Eccentricity The length (in µm) of the deviation between the center of the ferrule and the center of the core of the optical fiber. *10.PVC sheath This polyvinyl chloride (PVC) sheath, referred to as optical fiber cable, has a protective fiber coating. This type of sheath is mainly used indoors. *11.Hytrel ® core Hytrel ® is a polyester elastomer made of thermoplastic resin that was developed by the Dupont Corporation. This substance is an engineering plastic with superb features such as strength and heat characteristics. Hytrel ® core is a fiber optic stranded conductor coated with this elastomer. [Bibliography] 1) "Generic Reliability Assurance Requirements for Passive Optical Components", Telcordia GR-1221-CORE Issue 2, 1999 2) T. Tomasi, I. De Munari, V. Lista, L. Gherardi, A. Righetti, M. Villa: "Passive optical components: from degradation data to reliability assessment-preliminary results", Microelectronics Reliability 42, p.1333-1338, 2002 3) A. Piccirillo, G. Zaffiro, T. Tambosso, G. Gallo: "Reliability of Optical Branching Devices", IEEE (Institute of Electrical and Electronics Engineers), Journal of Selected Topics in Quantum Electronics, Vol.5 No.5, 1999 4) F. Caloz, D. Ernst, P. Rossini, L. Gherardi, L. Grassi, J. Arnaud: "Reliability of optical connectors - Humidity behavior of the adhesive", Microelectronics Reliability 42, p.1323-1328, 2002 5) Tetso Kumazawa, Makoto Shimaoka, Kazuyuki Fukuda: "Moisture Absorbency of Optical Components Resin Adhesive" Journal of Japan Institute of Electronics Packaging, Vol.4, No.7, p.621- 624, 2001 - 11 - Espec Technology Report No20
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