The passive optical power splitter is one of the key elements in a passive optical network (PON), which equally splits the signal power from the optical line terminal (OLT) in the central office (CO) to each optical network unit (ONU). It can branche and couple waves without converting optical transmissions into electric signals, for connecting households to thlecommunication carriers in optical communication networks. Planar lightwave circuits (PLC Splitter) can provide various key practical devices for such optical networks because of their suitability for large-scale integration, long-term stability, and mass production capability. In order to utilize the integration capability of PLC devices, the input and output fibers have to be connected to the PLCs. The fiber connected splitters are required to exhibit not only htgh optical performance (such as low loss, wavelength flatness and low polarization dependence) but also long-term reliability. However, to attain a reliable low loss splitter, connection methods must be precise and meticulous.
Figures1 a and b show typical schematic configurations of an unpackaged and a packaged PLC-type optical splitter, respectively. The unpackaged 1×8 PLC Optical Splitter includes a PLC (splitter) chip, and single-channel (input) and eight-channels (output) fiber arrays. The three parts are mounted by an adhesive, as shown in Fig 1a. However, in a packaged device, the mounted optical splitter is secured in its housing by applying fixing adhesive between the Al fixing blocks and the fibers. Moreover, an adhesive is used to bond the rubber boots and the end of fiber arrays in the housing, as shown in Fig1b. It is very clear that different types of adhesive are nedded for bonding different parts of the PLC package. In fact, a large number of different materials are ultimately required for assembling the splitter packages. Table 1 shows the physical properties of materials used in an adhesive-based optical splitter package. Shows the appearance of a bonded PLC optical splitter package in an aluminum package.
Figures 1 （a）Schematic configuration of unpackaged PLC optical splitter.
(b) Schematic configuration of packaged PLC optical splitter.
Physical properties of materials used in adhesive-based packaging of an Optical Splitter