Testing Fiber Optic Couplers In A Mass Production Environment

Abstract

INTRODUCTIONOptical fiber technology is finding wide ranging applications in many areas including communications and sensors. In applications, such as "Fiber to the Home" (FTTH), large quantities of fiber optic components will be used and subjected to environments not usually encountered in "Central Office" applications. In Figure 1 a typical "POTS /Video" subscriber loop topology is shown. Telephone Cent r a I node service (POTS) will operate in a bidirectional mode over a single fiber at one wavelength and video will be broadcast over a second wavelength to the subscriber. From the figure it can be seen that the link for a single subscriber requires two 3 dB couplers at wavelength 1 and two Wavelength division multiplexers operating at wavelengths 1 and 2. If interactive video, such as Video -Phone, is required an additional two 3 dB Tx couplers, operating at wavelength 2, will be needed. A 1 Rx Modu leDevices at the subscriber end of the system will be located in a box on the wall of the residence /office or located in a pedestal on the curb -side. In both scenarios the devices will be subjected to the full range of environmental parameters, from the extremes of -40 C in winter to high humidity at +40C in the summer. Inside the Remote Electronic Site (RES) temperatures of up to 80 C could be experienced at certain locations. Tx )12 Module Figure 1. Subscriber loop network for "POTS" and video.Consequently, it is important from the maintenance cost perspective that installed fiber optic devices operate over these extremes of conditions and have mean time to failures in excess of 20 years. In addition to meeting these specifications there is a requirement to manufacture these devices in high volume at low cost. In order to meet these last two requirements it is necessary to fully comprehend the manufacturing process with respect to process limits -performance specifications -reliability trade -offs.The application of modern manufacturing philosophy with statistical process control and careful product design argues that there is no reason for defects.In this paper details will be presented of the testing techniques that allow the process limits to be specified and the testing levels that enable tracking of the performance of the manufactured devices.