By Mark Brown, 13 June 11 via Wired UK
"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 jellyfish bioluminescent, 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 sizes: the mirrors were spaced 20 micrometres apart (20 millionths of a metre), and the cell was just 15 to 20 micrometres...."