Abstract: A bi-directional multiplexer/demultiplexer comprises a common port, an upgrade (UPG) port, a plurality of input/output ports, a plurality of wavelength division multiplexing (WDM) filters arranged in a zig-zag fashion, and a single bi-directional tap. The single bi-directional tap directs a tapped signal to a demultiplexing tap port in demultiplexing mode and a multiplexing tap port in multiplexing mode. The bi-directional tap may be a thin-film tap filter.

Abstract: A pluggable LC adaptor comprises a LC adaptor housing and an assembly, wherein the assembly is disposed in the LC adaptor housing. The assembly comprises: a first fiber collimator having a first lens; a first LC ferrule; a first fiber, where the first fiber is partially disposed inside the first LC ferrule and partially disposed inside the first fiber collimator; a second fiber collimator having a second lens; a second LC ferrule; a second fiber, where the second fiber is partially disposed inside the second LC ferrule and partially disposed inside the second fiber collimator; and an optical passive element disposed between the first collimator and the second collimator. The optical passive element may be a thin film filter or an isolator core.

Abstract: An apparatus for multiplexing and demultiplexing comprises: a substrate having a first surface and a second surface, where the second surface is opposite to the first surface; a first fiber array unit disposed on the first surface of the substrate and a second fiber array unit disposed on the second surface of the substrate, where a plurality of fibers in a fiber array unit are arranged in an array on a chip; a first microlens array disposed on the first surface of the substrate and a second microlens array disposed on the second surface of the substrate; a plurality of thin film filters disposed on the first and second surface of the substrate, where each thin film filter transmits light having a different wavelength band; a fiber collimator disposed on the first surface of the substrate; a turning prism disposed at an edge of the substrate for turning light from the first surface to the second surface of the substrate or also turning light from the second surface to the first surface of the substrate.

Abstract: Techniques for designing compact free-space optical device with all input/output ports on one side are disclosed. Instead of folding a fiber, a beam folding means is provided to turn a light beam to significantly reduce the size of the device. In one embodiment, there are a first collimator, a second collimator, and a beam folding means to turn a light beam from the first collimator back to the second collimator by two turns so that a first light path from the first collimator to the beam folding means and a second light path from the second collimator to the beam folding means are parallel. A substrate is provided to which the first and second collimators and filters are boned thereto.