• Modelling the Properties of Intracellular Microlasers

The integration of photonic devices with living biological cells promises to open new avenues in both biophysics and photonics. In particular, this includes novel imaging methods, which are necessary to further our understanding of complex biological processes such as disease mechanisms, with applications in medicine.

Ideal candidates for this are optical resonators supporting so-called Whispering Gallery Modes. They offer a unique combination of high spectral purity of emission and small size. This allows the resonators to integrated with individual cells and operate as both sensors and optical barcodes. These modes can lase if provided with a suitable gain medium, allowing cells to act as self-sufficient miniature lasers.

In this work we use numerical methods to characterize semiconductor disks as an innovative design for intercellular lasers. The disks have the advantage of significantly lower volume than competing designs, making the technique compatible with a greater range of cells. Using the Finite Element Method (FEM) and the Finite Difference Time Domain (FDTD) method, we calculate resonant frequencies and spectral purity of emission. We also calculate their sensitivity to perturbations of both external refractive index and resonator shape, with the aim of using the resonator as a sensor of intracellular force. Our designs have a force sensitivity only an order of magnitude less than contemporary force-sensing techniques. We anticipate this could be easily increased by further optimization of size and material composition. Together, these results represent a step towards realizing adaptable in-vivo sensors and explore the opportunities at the intersection of contemporary photonics and cell biology.