White Paper: Properties & Reliability Of Improved Large Acceptance Optical Fibers

Laser based applications in micro-packaging, microelectronics, and optoelectronic manufacturing benefit from the use of optical fibers coupled to the laser sources. Both economical and technical benefits are possible. Efficient coupling is key to accepting laser beam energy into the fibers for many cases. In some cases the ability to spread the output may be the key factor. The availability of optical fibers having low optical losses and high numerical apertures provide the opportunity to use smaller dimensioned fibers while still maintaining highly efficient coupling. Smaller fibers are more flexible, more resistant to fatigue, occupy less space and weigh less.

Classically, using laser energy for other than communications, data transfer, or sensing usually involves lasers with moderate to high output power, as in laser welding, marking or ablation. Transmission of such laser energy requires a medium with high temperature stability and ultra low loss, so that potential heat gain from internal absorption and its effects are minimized.

Silica is a good material in terms of both its optical and thermal properties. It can be produced synthetically with ultra-high purity and it has little absorption across a wide range of wavelengths from about 200 nm to over 2000 nm, especially when its production processing includes minimization of OH bonds within the glassy silica structure. The glassy region for silica is thermally stable to well above 1500 C. The bond energy of silica is greater than 20 GW/cm2. Silica core/clad fibers are thus among the best materials to use in optical fibers for high energy laser transmission.