Due to their small sizes and low threshold, nanolasers play a pivotal role in the field of low-energy scalable photonic technologies. High-speed modulation of nanolasers is needed for their application in data communication, but its implementation has been hampered by the small scales involved, leading to large electrical parasitics. Here we experimentally demonstrate the proof-of-principle of a novel modulation technique, namely, mode-field switching, which unlocks the control of the laser operation via the modulation of the electromagnetic field. In particular, we show that stimulated emission can be inhibited by switching the lasing mode from bright to dark in a three-coupled cavity system. The experimental results are in good agreement with a model that combines coupled-mode theory and rate equations. Using this model, we show that time-dependent detuning schemes enable storage and release of energy under the form of short pulses, placing mode-field switching among the techniques for laser modulation and pulse generation. This scheme is general and can be implemented in every platform displaying coupled and tuneable resonances.