Filtering of an optical WDM signal by using wavelet analysis

Wavelength division multiplexing WDM is on promising approach that can be used to exploit the huge bandwidth of optical fiber. In WDM, the optical transmission spectrum is divided into a number of wavelength bands, with each wavelength supporting a single communication channel. Thus, by allowing multiple WDM channels to coexist on a single fiber, we can tap into the huge fiber bandwidth, with the corresponding challenges being the design and development of appropriate network architectures and optical devices. This paper presents a novel signal processing technique based on the wavelet transformation of a received signal from two channels WDM system. Therefore the wavelet analyse is used for decoding and de-noising the received signal. We found that the signal filtering (de-noising) by using wavelet analysis is more optimal than filtering by utilizing the classical filter from the point of attenuation, phase shifting and signal spectrum deformation. The continues wavelet transform is successfully employed to decode and de-noise the received signal for different wavelengths separation (3,1 and 0.5 nm). Furthermore the selection of the wavelet type and the decomposition level is one of the most important parameters. We noted that in our case the haar and db wavelets are the most appropriate ones. Otherwise the decomposition level depends on the noise form.