The precision TFF POSA is formed by pressing a TFF glass rod array into a top surface of a master glass block to flatten the otherwise curved TFFs formed using conventional TFF deposition processes on glass. The TFF glass rod array is secured to the master glass block with a securing material to form a fabrication structure, which is singulated to form precision TFF POSAs having TFF members with flat TFFs and long TFF member long axes. A fiber interface device is arranged at a back surface of the TFF POSA. Other fiber interface devices having device axes are arranged proximate the TFF members. The device axes are parallel to the TFF member long axes to form a WDM system with a parallel configuration. In this configuration, there is one positionally adjustable fiber interface device for each wavelength channel, which allows for optimizing WDM optical communication in Mux and DeMux directions.