Evaluating the reliability of optical connectors

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Evaluating the reliability of optical connectors Test time (h) (a) SC connector insertion loss Test time (h) (c) FC connector insertion loss - 6 - Test time (h) (b) SC connector return loss Test time (h) (d) FC connector return loss Fig.6 Results of the High Temperature Storage Test (Damp Heat) (light source wavelength: 1310 nm) 6-2 Results of the Temperature Cycling Test Almost no differences were seen between the FC connectors and the SC connectors in the Temperature Cycling Test. Fig.7 shows partial measurement results for the SC connectors. Some insertion loss change and return loss change was seen following temperature changes in the temperature chamber during the Temperature Cycling Test, but these changes did not exceed the evaluation standard limits. The changes included insertion loss occurring at low temperatures, but no major fluctuation was seen at high temperatures. Return loss, however, tended to increase at high temperatures. Looking at the return loss changes over the long term confirms that as soon as return loss increases, the fluctuation stabilizes. This is thought to indicate that return loss quality stabilizes due to the adhesion of the connectors over time. Espec Technology Report No20
Evaluating the reliability of optical connectors (a) Insertion loss (b) Return loss Fig.7 Results of the Temperature Cycling Test (SC connectors; light source wavelength, 1310 nm) 6-3 Pistoning measurement results Measurement results for the ferrule tip surfaces did not indicate major changes in eccentricity and curvature radius, but the measurements confirmed that changes occurred in pistoning compared to the initial values. Fig.8 shows pistoning measurements after 1000 and 2000 hours of the High Temperature Storage Test (Damp Heat), and after 500 cycles of the Temperature Cycling Test. This report represents the direction of pistoning as a negative value. In the IEC, the standard for tolerance is recommended as -50 to 100 nm, and this level is exceeded, but the insertion loss and return loss measurements did not exhibit conspicuous fluctuation. On the other hand, optical connectors with powerful insertion light may be subject to influence by pistoning. Because of this, we face the challenge of investigating the relationship between pistoning and optical characteristics in such areas as manufacturing conditions. In this research, more pistoning occurred in the Temperature Cycling Test than in the High Temperature Storage Test (Damp Heat), regardless of whether the type of fiber coating included Hytrel ® core or the PVC sheath. The cause for the increased pistoning is thought to include stress in the direction of the pistoning from contraction and peeling of the adhesive. This, in turn, is thought to be possibly caused by the effects of humidity and the re-hardening of the adhesive at the test temperature (85°C) for reliability testing. - 7 - Espec Technology Report No20
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Evaluating the reliability of optical connectors

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