The need for flexible optical network architectures will increase as network operators attempt to support dynamic bandwidth demands. A very flexible broadband wavelength multiplexer with unique characteristics has been developed for use in flexible optical networks. This technology innovation allows flexible multiplexing of single channel traffic and multi-wavelength traffic onto one fiber. Multi-wavelength traffic spaced 100 Ghz apart modulated at 10 Gb/s is multiplexed while introducing minimal optical impairments. A significant reduction in interchannel crosstalk-like noise generated by interactions of closely spaced channels in multi-wavelength traffic is achieved.