This thesis presents a realisation of the most demanding laser systems for a mobile strontium optical clock. First, stable 689 nm cooling lasers are presented: an amplified semiconductor diode laser and a prototype of the semiconductor disc laser (SDL/VECSEL). The first was stabilised to a novel miniaturised multi-laser frequency stabilisation system that allows to stabilise all the six lasers used in the strontium optical clock. The latter was used for the first time in the second-stage cooling of strontium to obtain a cold cloud of trapped atoms. An atomic optical clock requires a laser oscillator for interrogating the clock transition. This thesis presents the construction and discusses the performance of the cutting-edge ultra-stable interrogation lasers at 698 nm. One of the systems is a stationary system based at the University of Birmingham, with the instability of 5x10¹⁵. A mobile version of the interrogation laser is also presented and characterised in this work. The laser reaches instability of 8x10¹⁶, which is one of the best results for a mobile system. The mobile laser is a part of the space optical clock project (SOC2), in which a record-low instability for the bosonic strontium was observed of < 4x10¹⁶√τ.