While millimeter-wave frequencies are introduced in next-generation communication systems, the need for amplifiers with high power levels is steadily increasing. As an alternative to current tube amplifiers, solid-state based systems are of great interest. To that end, this work covers the analysis of gallium nitride (GaN) broadband amplifiers and associated combiner systems (SSPA) with an output power in excess of 100 W between 28 and 38 GHz.

Highly NV-doped bulk diamond is expected to find application as a laser crystal to promote the realization of diamond-based quantum technologies like solid-state masers, high sensitivity gyroscopes or multi-modal sensors. This dissertation elaborates on the synthesis of the desired quantum-grade diamond for cavity-based solutions and provides a deeper understanding on the essential factors.