Abstract: Provided is a solid electrolyte made of yttrium-doped barium zirconate having hydrogen ion conductivity, a doped amount of yttrium being 15 mol % to 20 mol %, and a rate of increase in lattice constant at 100° C. to 1000° C. with respect to temperature changes being substantially constant. Also provided is a method for manufacturing the solid electrolyte. This solid electrolyte can be formed as a thin film, and a solid electrolyte laminate can be obtained by laminating electrode layers on this solid electrolyte. This solid electrolyte can be applied to an intermediate temperature operating fuel cell.

Abstract: An optical module is disclosed where the module includes an optical active device mounted on a carrier via a sub-mount, and a lens assembly mounted on the carrier and optically coupled with the device and an external fiber. A feature of the optical module is that the lens assembly has a metalized portion fixed to the carrier by the soldering.

Abstract: A small Faraday rotator is placed in the inner space of a receptacle and a holder. Because the plane of polarization is rotated, even when backreflection light returns to a laser diode, the lasing state does not become unstable. Being placed in the inner space and fixed there, the Faraday rotator can be small and therefore does not increase the part cost notably. The assembly cost does not increase, because it is not required to tightly press-fit a member into a narrow hole.