Facet coating layers

A recent study (Osenbach et al., 1997) of the reliability of InP-based diode lasers in non-hermetic conditions has shown that the commonly used facet coating layer, yttria-stabilized zirconia (YSZ), degrades in the presence of water vapor. In a typical experiment with lasers operating under conditions of 85 °C and 90% RH, the lasers failed with a median life of less than 1000 h. In this study, the median life of these lasers was determined as a function of RH and temperature, so that acceleration factors for these parameters could be determined. Application of these acceleration factors indicated that the median life in a test at 85 °C and 90% RH must be at least 3000 h to meet the field reliability expected by telecommunications providers. Thus, typical lasers used in hermetic packages do not have sufficient reliability for non-hermetic applications. 

FIGURE 5 (a) L-I and I-V curves for a facet coated, conducting buffer layer device under room temperature pulsed operation and (b) the emission spectrum at threshold. 

It is obvious that in rubber processing there will be slip, because the surface of processing equipment in contact with gum rubbers and compounds is usually shiny. This is in contrast to plastic processing equipment, in which the surfaces become coated with a thin layer of the degraded material. With plastics this fact indicates the velocity of the melt at the metal interface is zero, i.e., laminar shear flow. A study of slip is multi-faceted, because there are many types of slip, a steady slip, slip with a lubricated layer, slip-stick, slip involving a fracture at the interface or ruhhing like a dynamic friction measurement. 

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