The PEC etching method has revolutionized microdisk laser manufacturing

Recently, nano and microdisk lasers have emerged as potential light sources and probes for different applications in the biomedical and nanophotonics industries. Their ability to obtain lasers with ultra-narrow band accuracy and deterministic wavelengths is important for diverse applications such as on-chip bioimaging, on-chip photon communication, biochemical sensing, and quantum photon information processing.

However, large-scale manufacturing of these precise wavelength nano - and micron disk lasers remains difficult. Existing nanofabrication processes introduce randomness in disk diameters, which makes it challenging to obtain deterministic wavelengths in laser batches.

To address this problem, a team of scientists from Harvard Medical School and Massachusetts General Hospital's Wellman Center for Optical Medicine has designed a ground-breaking photochemical-based (PEC) etching method capable of precisely tuning the laser wavelength of a microdisk laser with subnanometer accuracy. Their research was published in the gold open access journal Advanced Photonics.

This new technology facilitates the production of nano - and micron laser batches with predetermined and accurate emission wavelengths. The application of PEC etching is the basis of this innovation, which provides a successful and scalable way to refine the wavelength of microdisk lasers.

In their study, the group effectively implemented SIO-2-covered indium gallium arsenide phosphide microdisks on an indium phosphide column structure. Next, by photoelectric chemical etching in a dilute sulfuric acid solution, they controlled the laser wavelength of this microdisk to a precise value.

In addition, they investigated the fundamental dynamics and mechanisms of etch in specific PEC. Finally, they transferred an array of wavelength-tuned microdisks onto a polydimethylsiloxane substrate, producing independent, isolated laser particles with different laser wavelengths. Subsequent microdisks show laser emission with ultra-narrow bandwidths of less than 0.6 nm for lasers on columns and less than 1.5 nm for isolated particles.

This discovery lays the foundation for several new biomedical and nanophotonics applications. For example, stand-alone microdisk lasers can be used as physico-optical barcodes for heterogeneous biological samples, helping to label specific cell types and target specific molecules in multiple assays.

Currently, cell type-specific labeling is performed using conventional biomarkers, such as quantum dots, organic fluorophores, and fluorescent beads, which have wide emission line widths. Therefore, only a few specific cell types can be labeled simultaneously. In contrast, microdisk lasers have ultra-narrow band light emission that will help identify a greater number of cell types simultaneously.

Therefore, the team evaluated and effectively established precisely tuned microdisk laser particles as biomarkers, using them to label live normal breast epithelial cells MCF10A in cultures. With their ultra-narrow bandwidth emission, these lasers have the potential to revolutionize biosensing through the use of well-proven optical and biomedical techniques such as flow cytometry, cytodynamic imaging, and multi-omics analysis.

The PEC etch-based approach marks a significant advance in microdisk lasers. In addition to subnanometer accuracy, the scalability of the technology also opens up new opportunities for numerous applications of laser recognition in biomedical and nanophotonics devices, as well as barcodes for specific cell populations and analytical molecules.

Source: Laser Network