Photonic integration technologies allow for fabrication of on-chip laser sources and systems that provide functionalities for applications beyond telecommunications, such as sensing, healthcare, millimeter and terahertz generation and quantum technologies. New applications impose a different range of demands regarding performance of such semiconductor laser sources. All characteristics of the optical output signal, output power, wavelength tuning range and mechanism, long and short term stability as well as the energy footprint have to be considered. Monolithic integration technologies on indium phosphide substrates natively support an on-chip combination of active and passive functions that enable development of a new class semiconductor lasers with complex cavities. Such lasers can be tailored to achieve optimum performance with respect to a specific application. A number of single frequency, tunable laser sources in form of photonic integrated circuits for applications in gas sensing, optical coherence tomography, millimeter and terahertz generation and quantum applications have been developed at Eindhoven University of Technology. Ongoing research and development activities that address challenges related to addressable wavelength bands, wavelength tuning and stability imposed by specific applications are enabled by mature generic monolithic technology on indium phosphide. In parallel to those efforts, extensive research works towards expansion of accessible wavelength bands. Tunable and mode-locked leaser geometries and challenges related to unique performance expectations are presented.