Facile layer-by-layer fabrication of semiconductor microdisk laser particles.

Semiconductor-based laser particles (LPs) with exceptionally narrowband spectral emission have been used in biological systems for cell tagging purposes. Fabrication of these LPs typically requires highly specialized lithography and etching equipment, and is typically done in a cleanroom environment, hindering the broad adoption of this exciting new technology. Here, using only easily accessible laboratory equipment, we demonstrate a simple layer-by-layer fabrication strategy that overcomes this obstacle. We start from an indium phosphide (InP) substrate with multiple epitaxial indium gallium arsenide phosphide (InGaAsP) layers which are sequentially processed to yield LPs of various compositions and spectral properties. The LPs isolated from each layer are characterized, exhibiting excellent optical properties with lasing emission full width at half maximum as narrow as < 0.3 nm and typical thresholds of approximately 6 pJ upon excitation using a 3 ns pulse duration 1064 nm pump laser. The high quality of these particles renders them suitable for large-scale biological experiments including those requiring spectral multiplexing.