By Mark Brown
Medical researchers from Harvard University have created the first “living laser”; a biological cell that’s been genetically engineered to produce a visible laser beam.
Lasers need two things to generate beams. They need a gain medium that amplifies light, and an arrangement of mirrors to concentrate and align that light.
Normal lasers, ever since their invention in the 1950s, use synthetic gain materials like gases, crystals and dyes to amplify photon pulses. But professor Seok-Hyun Yun and colleague Malte Gather, instead used green fluorescent protein (GFP), which is used to make jellyfishbioluminescent, as their gain material.
The team genetically engineered human embryonic kidney cells to produce GFP. They then placed a single cell between two mirrors. In terms of size, the mirrors were spaced 20 micrometers apart (20 millionths of a meter), and the cell was just 15 to 20 micrometers.
When the team ran pulses of blue light through the kidney-jellyfish combo, a visible laser beam shot out. It only lasted for a few nanoseconds, but the light could be easily detected and carried useful information on the properties of the cell. The cell also left the experiment unharmed.
Yun and Gather also noticed that the cell’s natural spherical shape acted like a lens, refocusing the light to induce laser emissions at lower energy levels than needed in traditional lasers with synthetic gain materials.
The technique has important applications in scientific and medical fields. Biologists can turn cells into lasers to better study their properties and makeup.
There’s also the possibility, albeit one that’s a long way off, that doctors could one day make laser beams inside a patient’s body, to lase hazardous or cancerous tissue from deep inside the body, rather than firing a laser from outside the skin.