Minimal-footprint photonic crystal nanolasers for biointegration

TL;DR

This paper presents the development of ultra-compact, substrate-less photonic crystal nanolasers with minimal footprints suitable for biointegration, enabling high localization and potential intracellular sensing applications.

Contribution

The authors identify the minimal size for lasing in 2D photonic crystal arrays and fabricate substrate-less nanolaser particles as small as 30 μm², suitable for biointegration.

Findings

Achieved active area as small as 30 μm² for nanolasers.

Demonstrated mass production and integration into live cells.

Designed NIR-II probes with mode volumes in the tens of attolitres.

Abstract

Photonic crystals allow unprecedented control over how light is confined, propagates, and interacts with matter. Their development has had a transformative impact on optics and physics, and they remain the central platform for both fundamental discoveries and practical photonic technologies. However, the relatively large footprint and substrate-bound nature of photonic crystal structures have so far strongly limited their use as miniature optical devices or biointegrated sensors. Here, we overcome these limitations by identifying the minimal size of a 2D photonic crystal array needed to achieve lasing and describe the fabrication of substrate-less hexagonal laser particles with an active area as small as 30 {\mu}m2. Massively parallel fabrication, robust detachment, and integration of the nanolaser particles into live cells is demonstrated. Crucially, by engineering spatial and spectral mode characteristics, we designed NIR-II probes with mode volumes on the order of tens of attolitres, an order of magnitude smaller than whispering gallery probes of similar dimensions. Such high light localization is comparable in scale to different organelles of eucaryotic cells. In the future, we expect that chemical or plasmonic functionalization of the device will enable label-free sensing of nanoscale intracellular processes, and that it shall serve as a miniature platform to exploit developments in optical and quantum sensing for chemical and biological applications.