Electro-thermal poling of microfibers

Abstract

In-fiber modulators are extremely attractive for telecommunication applications, and electro-thermal polin can be used to induce the necessary second-order nonlinearity in the glass fiber [1]. Long et al. have recently reported a way of mounting and poling D-fibers that is extensible to volume manufacturing and a relatively low voltage modulator has been demonstrated [2]. D-fibers are rugged, particularly if inbeded i a resin such as polyimide, but restrict the choice of available fibers, are not easily spliced, and a part of the voltage applied externally is wasted in biasing the cladding, unless further polishing/etching is used to remove the cladding and leave only the core region of the fiber. In the present work, we describe an alternative approach to making a fiber modulator, where pieces of conventional fiber are used, the central part of which is etched to the core and subsequently poled. After etching, the fibers have a diameter of ~10 μm and therefore are referred to as microfibers. Microfibers are surprisingly strong for their diameter and have some unique advantages. They can be fabricated with any fiber, the two ends that are not etched are truly easily spliceable, and the applied voltage during poling and in later use of the modulator develops mainly in the core, ensuring a large overlap integral.