Lars-Erik Nilsson

Integrated fiber Mach-Zehnder interferometer for electro-optic switching.

Molten alloys under high pressure were used to obtain fibers with long internal electrodes that are solid at room temperature. An integrated Mach-Zehnder interferometer was constructed from a twin-core twin-hole fiber that permitted application of an electric field preferentially to one of the cores. Good stability and a switching voltage of 1.4kV were measured with a 1-m-long fiber device with a quadratic voltage dependence.

In-fiber electrode lithography

The fabrication of meter-long continuous internal fiber electrodes is achieved through deposition of a silver film inside a twin-hole fiber. Photolithography of the electrodes with 5-μm resolution inside the fiber is demonstrated by point-by-point side exposure to 0.53-μm radiation through the unharmed acrylate coating, causing laser ablation. A proof-of-principle experiment demonstrates the creation of a phase-matched structure for frequency doubling.

Packaging process of fiber bragg grating strain sensors for use in high-temperature applications

In this paper, we report the development of a new bonding agent and method for the surface mounting of optical fiber Bragg grating (FBG) strain and temperature sensors for use in high temperature environments--where there is a presence of water, moisture, dust, susceptibility to corrosion and/or elevated temperatures up to 800°C. To ensure a stable reflectivity response of FBGs and their survival at elevated temperatures, we are using chemical composition gratings (CCGs). The refractive index modulation in these gratings is caused by a chemical change, which results in a higher activation energy and stable behavior up to 1000°C. Samples of CCGs were successfully encapsulated and mounted onto metal shims. The packaged sensors were tested for strain (+/- 1000με) and temperature (to +400 °C) response. The encapsulated sensors display a linear response with an increase in the temperature sensitivity of the FBG, with a factor of ~ 28.34pm/°C, and a strain gauge factor of 1.7pm/με.

High-Speed Switching in Fibres with Electrodes

Fibres with holes are provided with metal electrodes that fill the entire cross-section of the holes. Refractive index change and birefringence result from applying high current pulses for time intervals in the nanosecond range. High-speed polarization rotation and fibre Bragg grating wavelength tuning can be accomplished. Such electrically driven components are totally spliced with low insertion loss. They have no moving parts, are < 10 cm long and can be used in fibre laser cavities for Q-switching.

Specialty Single-Mode Fibers

This chapter provides an overview of unusual multifunctional, specialty single-mode fibers-macrohole fibers, multicore fibers, fibers with internal electrodes, and fibers for high-temperature resis ...