Biologists typically use fluorescent dyes or fluorescent proteins to track the location of cells. By replacing them with tiny lasers, scientists can track more cells without forgetting which cell is which. This is because the light produced by each laser contains only one wavelength. In contrast, dyes produce multiple wavelengths of light in parallel, which means that one can't accurately distinguish between the light from more than four to five different dyes, which become too similar in color. Instead, the researchers have now shown that it is possible to generate thousands of lasers, each producing light at a slightly different wavelength, and to distinguish between them with great certainty.
The new lasers come in the form of tiny disks, much smaller than the nuclei of most cells. They are made of a semiconductor quantum well material to provide the brightest laser emission and to ensure that the lasers are colored to match the cell. Although lasers have been placed in cells before, early experiments have taken up more than a thousand times the volume of the cell and require more energy to work, which limits their applications, especially for tracking immune cells into localized inflammation or monitoring the spread of cancer cells through tissues.
Lasers, as a means of causing irritation, mutation, combustion and vaporization in living organisms, have achieved good results in practical applications in medicine and agriculture; in the field of communications, light-conducting cables transmitting signals with laser columns can carry the amount of information carried by 20,000 telephone copper wires; in addition to being used for military communications, night vision, early warning and ranging, a variety of laser weapons and laser-guided weapons have also been put into use.
When they started working on topological insulator lasers, no one believed it was possible because the known concept of topology was limited to systems that did not and could not have gain. But all lasers need gain. So topological insulator lasers are the opposite of everything known at the time. In fact, VCSELs can be combined theoretically and experimentally to obtain stronger and more efficient lasers. Thus, this result paves the way for many future technological applications, such as medical devices, communications, etc.