Optical second harmonic generation in dense wavelength division multiplexing (DWDM) was used to monitor the performance of each channel in all optical DWDM networks. A highly nonlinear photonic crystal fiber is used to convert C and L bands optical channels into half wavelength channels where silicon arrayed detectors and CMOS electronics were used to perform advanced digital signal processing to predict the optical channel presence, channel power, signal to noise ratio and the quality factor (Q) parameter. With further processing, the bit error rate per channel can be estimated from the Q factor.