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08 Nov 2006
Researchers demonstrate a miniaturized fiber laser in their quest to develop a compact light source for sensing and communications applications.
Scientists in China have made easy work of designing a miniature fiber laser. Aimed at communications and sensing applications, the compact light source is created by simply tying a knot in a length of doped microfiber. (Appl. Phys. Lett. 89 143513)
"The design is very compact and easy to make," Limin Tong of Zhejiang University told optics.org. "You can fabricate a microfiber knot laser in several minutes by hand."
The group forms its device by tightening a 3.8 µm diameter, Er:Yb doped phosphate glass microfiber into a 2 mm diameter knot under a microscope. Pumped by a semiconductor diode laser operating at 975 nm, the knot emits light at 1.5 microns and acts as both the active medium and resonating cavity. According to the researchers, the maximum single-mode output is about 8 µW at the maximum available pump power of 12.8 mW.
When quizzed about bending losses, Tong explained that the high-index contrast between the fiber and the surrounding air gives considerable scope for reducing the diameter of the knot. In fact, he believes that knots with diameters in the region of tens of micrometers should be feasible.
"The biggest challenge is to optimize the knot to give high-Q resonance for the pump and the lasing light," Tong revealed. "The next step is to make the laser more practical by reducing the size, lowering the threshold and increasing the efficiency."
The group has submitted a patent for its device and is keen to commercialize the design.
Author
James Tyrrell is News Editor of Optics & Laser Europe magazine and a contributor to optics.org.
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