Laser spot position dependent photothermal mode cooling of a micro-cantilever

TL;DR

This paper investigates how the position of a laser spot affects photothermal cooling of a micro-cantilever's mechanical modes within a Fabry-Pérot cavity, revealing position-dependent coupling behaviors and optimizing cooling efficiency.

Contribution

It introduces a theoretical model explaining laser spot position effects on photothermal coupling, supported by experimental validation and simulations identifying optimal regions for mode cooling.

Findings

Photothermal coupling varies with laser spot position along the cantilever.

Parallel coupling regions enable more efficient mode cooling.

Theoretical model aligns quantitatively with experimental results.

Abstract

We explore the laser spot position (LSP) dependent photothermal mode cooling of a micro-cantilever in a Fabry-P\'erot (FP) cavity. Depending on the LSP along the lever, photothermal coupling to the first two mechanical modes can be either parallel or anti-parallel. This LSP dependent behavior is analyzed theoretically by a simple model, which is in quantitatively agreement with our experimental observation. From simulation, the parallel and anti-parallel coupling region is identified along the lever. We conclude that a more efficient mode cooling may be achieved in the parallel coupling region.