Filter-embedded design and its applications to passive components

Abstract

A new design in which a filter is embedded in a fiber fixed on a substrate is proposed, and it was successfully applied to fabrications of low loss fiber optic components for a single-mode fiber transmission system. These components are low in loss and wide in operational temperature range, and the design is easily adapted to a multifilter component or a multifiber component. Filter embedding was achieved in two ways. One is to insert a thin filter chip in a slit, which is machined into a fiber fixed on a substrate by a dicing saw ("filter inserted type"). The other is to evaporate a filter film directly on a fiber end face and butt this fiber to another fiber on a guide groove on a substrate (''filter evaporated type").

Polarization- and wavelength-insensitive guided-wave optical switch with semiconductor Y junction

“…However, none of them was wavelength insensitive, because their operation was based on mode interference. From a practical point of view, however, a wavelength-insensitive operation is preferable, because a wavelength division multiplexing technique is gradually getting its popularity in deployed communication systems [4], [5]. Recently, an optical switch [6]- [8] based on the mode evolution property [9], [ 101 of a LiNbO, asymmetric X or Yjunction was reported, and its polarization-and wavelength-insensitive operation was demonstrated by exploiting its "digital" response with respect to applied voltage.…”