February 27, 2004 Bath, UK -- BlazePhotonics recently announced a hollow core photonic bandgap fiber with a record loss of 1.7 dB/km near the 1550-nm wavelength. This represents more than a seven-fold improvement over the best previously reported value, say company representatives, who view the development as an important step towards making hollow-core fiber a practical proposition for long-haul transmission.
BlazePhotonics has developed a hollow core photonic bandgap fiber with an attenuation of 1.7 dB/km at the 1560- to 1575-nm wavelength. The mode size and mode profile of the fiber is comparable to that of SMF 28. Lengths of several kilometers were fabricated and loss and other key optical parameters showed excellent homogeneity over length, reports the company. The breakthrough was achieved by carefully controlling the cross sectional profile of the waveguide in order to minimize the amount of light that is in contact with the many air/glass interfaces in the fiber, a key contributor to loss in hollow core bandgap fibers.
"Perhaps the most exciting potential application for hollow core photonic crystal fiber is for it to become the next generation of ultra-low loss, ultra low non-linearity transmission fiber," contends Simon Haslam, chief executive officer at BlazePhotonics. "This work has brought us one important step closer to that goal."
Photonic bandgap fibers are optical waveguides in which hundreds of roughly wavelength-sized airholes that run along the axis of the fiber create a photonic bandgap in the fiber cladding that confines light to the core. Unlike conventional, all-solid fibers that guide light by total internal reflection, photonic bandgap fibers can be designed to guide light in an empty or gas-filled core. Since most of the optical energy does not travel in the glass, these fibers do not suffer from the same limitations of loss as conventional fibers and can exhibit significantly lower optical non-linearity.
Rapid progress has been made since air-guiding fibers were first demonstrated in 1999; however, the reduction of loss remains a key issue. Even the loss values now achieved by BlazePhotonics are still an order of magnitude higher than those of the best conventional fibers. That said, company representatives believe this recent achievement significantly improves attenuation, power handling capability, and other key optical properties of hollow core bandgap fibers for more near-term applications, including the delivery of powerful ultra-short optical pulses. BlazePhotonics now manufactures such hollow core bandgap fibers for a range of wavelengths from 440- to 2000-nm.