The linkOptical Schrödinger “cat” states between the physics of strong—laser fields and quantum opticsQuantum optics has recently opened up new frontiers for fundamental research and applications in quantum technologiesQuantum technologies and ultrafast science at the fully quantized level. One of the main achievements raised by this link is the generation of coherent state superpositions, namely optical Schrödinger “cat” states, which are considered as one of the main resources for investigations in quantum technologies. Specifically, it has been shown that fully quantized approaches in intense laser-matter interactions and the process of high harmonic generationHigh harmonic generation can be used to generate high mean photon number optical Schrödinger “cat” states and multi mode entangled statesEntangled states, ranging from the infrared to the extreme—ultraviolet. Here, after a brief introduction on the fundamentals, we will discuss some representative key developments in this research direction, emphasizing on the generation of optical “cat” states and their role in nonlinear optics.