Fujitsu Corporation

Teruhiro Kubo

Norihisa Naganuma

Nobuhiro Fukushima

Yoichi Oikawa

The invention aims to provide a miniaturized polarization measuring apparatus which can measure the polarization of input signal light with high accuracy, even in an optical system where a plurality of light receiving elements are arranged adjacent to each other. To this end, in the polarization measuring apparatus which branches the input signal light into four signal lights by optical couplers in a three stage configuration, and provides the signal lights with polarizations and the phase shifts, which are different for each signal light, by a plurality of optical elements arranged on branched optical paths, and detects the signal light powers by corresponding light receiving elements, and calculates the Stokes parameters or the like, based on the detection results, to thereby measure the polarization of the input signal light, the elements are arranged to be inclined to each other, so that an interference system is not formed between the adjacent elements on the same branched optical path, and also there is provided a shielding wall so that a stray light generated between these elements does not reach the light receiving element on another branched optical path.

Polarization measuring apparatus

A polarization state measuring apparatus of the present invention branches an input signal light into a plurality of signal lights by optical couplers, gives polarization and phase shift which are different from each other, to the signal lights by a plurality of optical elements arranged on optical branch paths, detects the power of each of the signal lights by the corresponding light receiving elements, and after adjusting at least differences in the optical branch paths, processes electrical signals output from the light receiving elements, to acquire information related to a polarization state of the input signal light. As a result, it is possible to provide a small size polarization state measuring apparatus which can correct differences in arrival times of the signal lights to the light receiving elements, to thereby measure the polarization state of the input signal light with high accuracy.

Polarization state measuring apparatus

There are provided an optical device, a terminal station apparatus and a system for wavelength division multiplex. An optical device comprises a WDM port, a specific port to which is allocated an intermediate wavelength between a long-wavelength group and a short-wavelength group, a plurality of ports to which are allocated those wavelength groups described above, and first to fourth optical filters.

Optical device, terminal apparatus, and system for wavelength division multiplexing

The invention provides an optical device suitable for use with an optical amplifier, for example, in an optical communication system and advantageous in that different functions of a plurality of optical elements are achieved using an optical element of a simple construction and the optical device can be produced in a reduced size at a reduced cost. The optical device includes a tapered prism constructed such that a first face and a second face thereof opposing to each other do not extend in parallel to each other. A dielectric multi-layer film is formed on the first face of the tapered prism positioned on an optical signal inputting side. A reflection film is formed on the second face for reflecting the optical signal inputted to the tapered prism through the first face at least once toward the first face. A non-reflection film is formed on one of the first face, the second face and the other face or faces of the tapered prism for extracting therethrough the optical signal inputted to and reflected in the tapered prism.

Optical device

A wavelength division multiplexing module capable of multiplexing or demultiplexing a plurality of optical signals having close wavelengths with less crosstalk. The wavelength division multiplexing module includes a housing having a bottom wall, a first side wall, and a second side wall inclined a predetermined angle with respect to the first side wall, and a common port assembly fixed to the bottom wall of the housing so as to emit a collimated beam substantially perpendicular to the first side wall. One or more filter port assemblies are fixed to the first side wall in the condition that the pass wavelength characteristic and optical axis of each assembly have been adjusted. Similarly, one or more filter port assemblies are fixed to the second side wall in the condition that the pass wavelength characteristic and optical axis of each assembly have been adjusted. Each filter port assembly includes an optical film holder rotatable in a hole having a center axis inclined a predetermined angle .theta.1 with respect to the optical axis, and a band-pass filter mounted in the optical film holder so as to be inclined a predetermined angle .theta.2 with respect to a plane normal to the center axis of the hole of the optical film holder.

Growing community of inventors

Yokohama, Japan

Teruhiro Kubo