Abstract: An optical circuit includes a light source having a low degree of polarization, an input section connected to the light source, and an output section connected to the input section. The input section has an optical waveguide incapable of maintaining a state of polarization. The output section has at least one optical waveguide having no branches. The optical waveguide having no branches has, in at least part thereof, an optical waveguide capable of maintaining a state of polarization.

Abstract: The infrared reflector of the present invention has an infrared-reflecting layer and an infrared-permeable layer which is formed on the infrared-reflecting layer. The infrared-reflecting layer has a reflectance of 60% or more and a permeability of 25% or less with respect to infrared rays having a wavelength within a range of 800 to 2600 nanometers. The infrared-permeable layer has a reflectance of less than 60%, an absorbance of 50% or less, and a permeability of 30% or more with respect to infrared rays having a wavelength within a range of 800 to 2600 nanometers. The infrared-permeable layer contains resin components and pigments, and the amount of carbon black contained in the infrared-permeable layer is 0.1 wt % or less.

Abstract: A conversion adapter to be used for connecting opposed optical connector ferrules having different diameters is formed of an amorphous alloy possessing at least a glass transition region, preferably a glass transition region of not less than 30K in temperature width. Particularly, the amorphous alloy of M1-M2 system or M1-M2-La system (M1: Zr and/or Hf, M2: Ni, Cu, Fe, Co, Mn, Nb, Ti, V, Cr, Zn, Al, and/or Ga, La: rare earth element) possesses a wide range of &Dgr;Tx and thus can be advantageously used as a material for the conversion adapter. Such a conversion adapter can be manufactured with high mass-productivity by a mold casting method or molding method.

Abstract: Disclosed are a sleeve for abutting, aligning, and retaining opposed optical connector ferrules and methods for the production thereof. The sleeve has a tubular body provided at three points on the inner wall surface thereof with ridges of an arcuate cross section extending from one to the other end of the tubular body in the longitudinal direction thereof and a slit formed therein in the longitudinal direction thereof. The sleeve is formed of an amorphous alloy possessing at least a glass transition region, preferably a glass transition region of not less than 30 K in temperature width.