Traceable Laser Power Measurement Using a Micro-Machined Force Sensor with Sub-Piconewton Resolution

For the traceable measurement of the laser power with high resolution and relatively large measuring range, a micro-machined pico-force sensor with integrated Fabry-Perot resonator is developed. This silicon force sensor features an integrated passive cantilever gripper, with which AFM cantilevers with high reflection coating for various wavelengths can be used as the reflector for laser power measurement, enabling a high flexibility of this silicon transducer. First measurements of the radiation pressure of a semiconductor laser revealed a noise limitation of the pico-force transducer of <;1 pN, corresponding to a power measurement sensitivity better than 120 μW.