As chemists, we are all impressed by the ingenuity and efficiency of the actuators that pave every Nature's machinery.1,2 Inspired by, but far from the smart life's molecular designs, chemists have gathered experience over the past decades in preparing efficient activatable molecular systems, in a wide range of purposes and scales.3-7 Among them, employing light as actuator offers the advantages of simple and contactless modulation of the intensity and space resolution, and can be used orthogonally to electronic processes. Controlling and understanding the dynamics of externally light-triggered molecular motion is one fascinating topic that spawned groundbreaking successes, ranging from biomedicine to smart molecular materials.8-10 Photochromic molecules stand as efficient molecular light-switches since they are able to undergo reversible photo-reactions by absorbing photons of suitable frequencies, which promotes different deactivation paths such as the formation of new chemical bonds and/or transforming their configuration leading to modulation of properties like electronic gap, polarity, or geometry. As far as molecular motion is concerned, the targeted photochrome must undergo photo-modulation of geometrical changes. Azobenzene derivatives are the most studied for their large geometrical changes upon light irradiation but suffer from low thermal stability. 11 We learnt during the journey of photo-activatable molecules that the specifications of reversibility, fatigue-resistance and nondestructive readout are crucial toward operating photo-responsive molecular systems, particularly in the fields of bio-imaging or molecular data storage.12-14 Besides, the choice of an optical output signal appears both beneficial and challenging.11,15,16 Among the all-optical molecular systems reported to date for the photo-control of linear or nonlinear17 optical output, a common design combines photochromic and fluorescent units, where the fluorescence emission is modulated by the photochromic reaction. Among the various photochromic compounds known to date, the dithienylethenes (DTE) are the most suitable for fluorescence photoswitching due to their excellent thermal stability and fatigue resistance. 16 Depending on the nature, the structure and the environment of the dyad, the usually observed destructive fluorescence readout can be due to, i) the fluorescence quenching process by excitation energy transfer which can trigger the cycloreversion reaction of the DTE unit, ii) the contribution of the triplet state in the photocyclization reaction or iii) the competition between fluorescence emission and photocyclization reaction. To overcome this issue, several strategies have been proposed, such as readouts using the changes of the refractive index or IR absorption at the wavelengths out of the switching unit, stabilized signals by means of acid or base reactions, switching by photoinduced electron transfer, 20 molecular polarity, or supramolecular conformational changes. While efforts have been made to reduce competitive processes to luminescence photoswitching, it is still very challenging to completely suppress the destructive readout in DTE-based systems.