17 Sep 2003
Researchers report a photonic-band gap fiber that can transmit megawatt pulses in this week’s Science.
A US team claims to have fabricated an optical fiber that can support soliton light pulses with a peak power of several megawatts -- several hundred times the power handling ability of conventional fiber (Science 301 1702)
The hollow-core photonic band-gap fiber (PBGF), developed by Corning and Cornell University both of the US, could prove useful for applications in spectroscopy, biology and medicine where high-power pulses need to be delivered through a fiber.
The PBGF is made up of a honeycomb silica structure that surrounds a central hollow core. In lab experiments, the US team have shown that a 170 cm long, Xenon-filled PBGF can transmit a 75 fs pulse with a peak power of about 5.5 MW. An air-filled version could handle peak powers of up to 2 MW.
The key to the fiber’s astonishing power handling is a dramatically reduced optical nonlinearity of just 3.02x10-19 cm2/W – three orders of magnitude smaller than normal fiber made of solid silica glass.
In standard fibers, optical nonlinearities such as Raman scattering limit transmission to pulses with just a few nanojoules of energy. In contrast, the honeycombed structure of the PBGF can support microjoule pulses.
“Because the dispersion of the PBGF is comparable to that of conventional single-mode fibers and the nonlinearity is 1000 times smaller, we expect that the PBGF can support solitons with peak powers that are about 1000 times those that can be supported by conventional single-mode fiber,” Dimitre Ouzounoiv and his co-workers said in a paper in this week’s Science.
“By injecting a gas, such as a noble gas which does not have a Raman component, into the fiber core it should be possible to maintain these high powers and intensities over distances exceeding 200 m,” predict the authors.