Rapid Electro-Thermal Micro-Actuation of Flat Optics Enabled by Laser-Induced Graphene on Colorless Polyimide Substrates

Abstract

A high-performance electro-thermal micro-actuator for active optical devices is demonstrated, fabricated via the direct laser writing (DLW) of laser-induced graphene (LIG) onto a colorless polyimide (CPI) substrate. This approach leverages the unique combination of LIG's exceptional thermal conductivity (4.70-11.3 W m(-)(1)K(-)(1), representing a two-order-of-magnitude enhancement over CPI) and CPI's inherent transparency, flexibility, and high thermal stability. The LIG exhibits rapid thermal actuation of optically reflective surface with frequencies up to 2 kHz. Furthermore, the optically diffractive electro-thermal actuators enable 0.5-millidegree-resolution beam steering with 0.9 s response times, transitioning the LIG actuators from the quasi-steady state to an active regime. This high-speed, high-precision actuation mechanism demonstrates the potential for high-speed dynamic optical control in compact systems, such as focus-tunable lenses and beam-steering devices. The single-step DLW fabrication process on a readily available, flexible, and transparent substrate offers significant advantages in terms of cost-effectiveness and scalability, making this approach highly promising for next-generation lightweight, flexible, and integrated optoelectronic devices.