Analysis and generation of (nonlinear) intermediate- to deep-water waves with large steepness in experimental facilities are some of the most challenging tasks in wave mechanics. The inherent instability of water waves in deep-water waves makes the linear-based wave generation and analysis less accurate and incapable of generating and characterizing correctly nonlinear behavior of the target wave field. In this presented research, a detailed assessment of the wavemaker theories and steps included in experimental approaches are presented. After establishing the nonlinear behavior of generated intermediate- to deep-water waves, a novel wavemaker theory based on the nonlinear Schrödinger equation is proposed. The implementation of the proposed wavemaker theory shows its capability of generating deep-water waves more accurately and preserving the correct order of nonlinearity.