LAUSR

DOI: 10.1002/adom.202000769 such as optical switching with organics,[5] optically switchable light-emitting transistors,[6] sub-femtojoule switches,[7] plasmonic bandpass filter thermal sensor switches,[8] optical control of antiferromagnetic domains[9] utilizing highmobility of cadmium oxide for ultrafast polarization-controlled[10] multimodal sensing switching of a redox-active macrocycle molecules state toggle,[11] active control of anapole states by structuring the phase-change alloy,[12] energy-efficient alloptical switching with graphene-loaded deep-subwavelength plasmonic waveguides,[13] and ultrafast optical switching of infrared plasmon polaritons in highmobility graphene.[14] The efficiency of the switch is defined by its size, which dictates the number of input and output ports; switching time of reconfiguration from one state to another; propagation delay time; switching energy to turn on the switch; power dissipation during the switching; crosstalk due to the power leakage to other ports; and physical dimensions.[3] Even though the optical fibers are considered a pivot of a conventional optic telecommunication system,[2] their role in switching and processing of photonic signals is limited and fulfilled by electronics. Here we report an all-optical switch engineered to operate at telecommunication wavelengths associated with the relaxation time of excited molecules in a hybrid plasmonic–dielectric configuration. By coupling photons to conductive charges at the metal–dielectric interface, plasmonics gives rise to nanoscale optical devices operating at sub-wavelength regime[15] due to the local field enhancement. The local field enhancement can be realized with plasmonic materials by means of collective oscillations of free electrons in the form of extended surface plasmon-polariton (ESP) in thin metal films[16] or localized surface plasmon resonance (LSPR) in plasmonic nanoantennas.[17] However, molecular overtone bands lying in the near-infrared (NIR) spectral region are forbidden in harmonic oscillator approximations.[18–20] Such bands arise only from the anharmonicity of molecular vibrations which are rather weak,[18] leading to overtone bands with the absorption cross-section of an order of magnitude lower than that of the fundamental modes with the same degrees of freedom. Here, we focus on a hybrid plasmonic–dielectric system consisting of excited LSPR of the gold Semiconductor transistors for sensors are considered the most widely manufactured device in history. Being invented to switch electronic signals they revolutionized electronics and paved the way for smaller and cheaper sensors, radios, calculators, and computers. However, electric switches are hampered by damage from very brief electrical and thermal effects or electromagnetic interference. For this reason, modern communication systems devote considerable attention to all-optical switches, yet, the state-of-the-art switching of photonic signals is fulfilled electronically. All-optical switching allows light-controls-light through unique optical effects. Here, an all-optical sensor switch, engineered to operate at telecommunication wavelengths, caused by the excitation of molecular overtones in a hybrid plasmonic–dielectric configuration is demonstrated. This configuration possesses a unique property: to control the sensor switch with the polarization state of light for two different plasmonic modes to co-exist while exciting a single overtone. Control of the sensor switch is realized by tuning the polarization of incident light from transverse magnetic (switch-on) to transverse electric (switch-off). This switch provides a miniature, affordable, and fast chip-scale polarizationactivated sensor device for a wide range of applications from optics communication to all-optical computing and sensing.