Abstract: An apparatus for controlling a tunable filter of the present invention includes a tunable filter, a generating device for generating a reference light whose wavelength is within a transmission wavelength band of the tunable filter, a detecting device for detecting an interaction signal, such as a beat signal, caused by interaction between a desired component of an input light to be input into the tunable filter and the reference light and a controlling device for controlling the tunable filter based on the interaction signal. The controlling device controls a current flow through a wavelength control terminal of the tunable filter such that a center filtering wavelength of the transmission wavelength band of the tunable filter substantially coincides with a wavelength of the desired component.

Abstract: In an optical amplifying apparatus of this invention, there are provided an optical amplifier part for giving a gain to an input light from outside and a selective loss part for giving a light loss of a prescribed ratio for different polarization modes in order to compensate for a polarization dependency of the amplification factor between the input and output lights. Thus, the difference of amplification factors for the different polarization modes is compensated for, as a whole of the apparatus. This polarization non-dependent type optical amplifying apparatus has solved the polarization dependency without degrading other characteristics, so that this can be preferably used in a optical communication system or network. Further, this amplifying apparatus does not require so many external optical components, so this is suitable to the fabrication of a module and is preferably contained in an integrated optical node.

Abstract: A ferro-sintered alloy having wear resistance at elevated temperatures comprising a matrix in which, on a weight basis, 25-75% of an alloying base A of the following composition is irregularly dispersed with 75-25% of an alloying base B of the following composition, the matrix having dispersed therein 3-15% of at least one of the following hard phases C and D, and optionally being impregnated in its pores with lead:______________________________________ Base A Base B ______________________________________ Cr 2-4% Co 5.5-7.5% Mo 0.2-0.4% Ni 0.5-3% V 0.2-0.4% Mo 0.5-3% C 0.6-1.2% C 0.6%-1.2% Fe the remainder Fe the remainder Hard phase C: 45-60% Co - 33-36% Mo. - and remainder Si Hard phase D: 45-60% Fe - 33-36% Mo - and remainder Si.

Abstract: A ferro-sintered alloy having wear-resistance at elevated temperatures, comprises a perlite matrix having a copper content of from 0.2 to 1.5% by weight. 10 to 50% by weight of a phase A rich in heat and corrosion resistance is dispersed in the matrix with phase A including 9 to 20% Cr, 6 to 15% Ni, 1.5 to 9.5% Mo, 1.5 to 9.5% W, 0.7 to 4.5 Cu and an Fe remainder. In addition, 2 to 15% by weight of an additional component is dispersed in the matrix which is selected from one of a group of components which are wear-resistant. The group of components comprises:50.about.70% Mo-Fe Alloy (by weight)50.about.70% Cr-Fe Alloy (by weight)45.about.60% Fe-33.about.36% Mo-Si Alloy (by weight)45.about.60% Co-33.about.36% Mo-Si Alloy (by weight).