Generic Foundry platforms represent an exciting breakthrough for photonics as a whole by making widely available an affordable solution to design and manufacture custom Photonic Integrated Circuits (PICs) . Of course, from the semiconductor laser point of view, the InP based platform is – at least for now – the most convenient for implementation of new laser concepts and design as both passive (e.g. waveguide or splitter) and active components (e.g. optical amplifiers and modulators) can be integrated on the same PIC. This led to the emergence of exciting new structures which exhibit outstanding performances. For example, in , Latkowski et al. have proposed and demonstrated a widely tunable ring laser structure. With a 70 nm tunability range, this device offers one of the largest tuning capability for a monolithically integrated laser. This has been achieved by introducing three Asymmetric Mach-Zender Interferometers (AMZIs) inside the laser cavity. With different optical path length differences, each of them plays the role of a frequency filter with a different spectral period. The filter frequency can then be tuned by adding a phase modulator inside one arm of each AMZI. As a result, a coarse, a medium and a fine tuning capability is obtained as detailed in .
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