Infraroter

Infraroter is a term occasionally used in nanophotonics to denote a rotor or rotatory micro device actuated by infrared light. The concept combines infrared energy with micro- or nanoscale rotors, typically relying on photothermal or angular-momentum transfer mechanisms to produce torques that rotate a shaft or blade assembly.

Principle: Infrared absorption by an asymmetric rotor can create a temperature gradient and differential expansion, producing a net torque around a central axis (photothermal torque). In some designs, circularly polarized IR light can carry angular momentum, enabling direct optical torque on birefringent or chiral structures.

Design and materials: Prototypes often use asymmetric nano- or microstructures such as helices, paddle wheels, or blades made from plasmonic, dielectric, or semiconductor materials, positioned in a low-friction environment (vacuum, gas, or liquid). Control is achieved by tuning IR wavelength, intensity, and polarization, sometimes with plasmonic resonances to enhance absorption.

Applications and status: If realized, infraroters could enable on-chip mixing in microfluidics, remote actuation in micro-robots, or sensitive rotation sensing. The term is not widely standardized, and practical implementations face challenges including heating management, efficiency limits, and integration with other micromechanical components. Ongoing research in optical micromotors and photothermal actuation informs related developments.

See also: optical torque, photothermal effect, nano-rotor, optical trapping.