Optical Bragg gratings are finding new applications in high frequency pulse generation and in multiple wavelength systems where great precision is required. Sampled Bragg gratings (SBGs) offer great design flexibility. Incorporating sampled grating reflectors in mode-locked semiconductor lasers allows stable pulse streams to be generated at THz frequencies. By using sampled Bragg gratings in distributed feedback laser arrays, the channel spacing can be defined in laser arrays with great precision. Furthermore, by introducing pi-shifted sections into the SBGs, the grating coupling coefficient can be enhanced, opening new avenues for the design and low-cost manufacture of photonic integrated circuits.