Dense wavelength division multiplexer(DWDM) is based on the membrane filter technique and proprietary non-flux metal bonding micro-optics packaging design, within ITU wavelengths to achieve uplink and downlink. It provides ITU channel center wavelength, low insertion loss, high channel isolation, low power consumption, wide passband characteristics, no glue loop, excellent thermal stability and reliability and so on. In a telecommunications network system, it can be used for uplink or downlink optical signal.