"Processing of high speed optical signals in the optical domain, referred to as optical signal processing, is required for many applications in the telecommunication systems and networks. Many optical signal processing techniques have been studied in the literature where most of them are based on nonlinear optics such as 2nd order and 3rd order nonlinear effects. A wide range of nonlinear media are used for performing these nonlinear optical signal processing applications such as optical fibres, semiconductor optical amplifiers, and different types of optical waveguides. In this thesis, we use nonlinear optics to perform nonlinear optical signal processing and microwave photonics applications. First we propose and experimentally demonstrate an optical signal processing module that will be used for recognition of spectral amplitude code (SAC) labels in optical packet-switched networks. We use the nonlinear effect FWM in a highly nonlinear fibre (HNLF) for generation of a unique FWM idler for each SAC label referred to as a label identifier (LI). A serial array of fibre Bragg gratings is then used to reflect the LI wavelengths. Each LI is associated with a unique amount of delay between two optical signals received at two photodiodes. Label recognition is then achieved by measuring this unique time delay. An experiment is conducted where two variable-length data packets are transmitted over a 50-km dispersion-compensated span of fibre and switched at a forwarding node. The SAC labels are successfully recognized, and we obtain error-free transmission for the switched packets with less than 0.3-dB penalty. Then using FWM in a HNLF and also a programmable planar lightwave circuit (PLC) we propose and experimentally demonstrate the all-optical reconfigurable time slot interchange (TSI) of individual bits at 40 Gb/s. The PLC is used to generate different control signals (masks) that determine which bits undergo TSI. By programming the PLC to generate two different masks, two different TSI patterns are obtained. TSI is achieved using FWM between the data signal and the desired mask with bidirectional propagation in the HNLF. Error-free operation is obtained for both of the TSI patterns, with a power penalty of less than 5.2 dB, at a bit error rate of 10-9.Next, we use a low-stress silicon-rich nitride waveguide as the nonlinear medium to perform two different applications based on XPM. The waveguide is engineered to display flat and low dispersion over the entire C+L bands. First, we demonstrate wavelength conversion of 10 Gb/s signals across the C band and obtain error free operation. We also demonstrate ultra broadband wavelength conversion over 300 nm from the O-band to the L-band. Second, we highlight the use of SixNy waveguides for nonlinear MWP. We report the first demonstration of an XPM-based radio-frequency (RF) spectrum analyzer of optical signals using an integrated silicon nitride waveguide. Measurements show a bandwidth of at least 560 GHz for our RF-spectrum analyzer. RF-spectra measurements for pulse trains at rates from ~ 10 GHz to ~ 160 GHz are demonstrated. These results show that the silicon nitride technology has a competitive performance for realizing high-speed optical processing of telecom signals." --