Abstract: Light beams emitted from an optical fiber are converted into parallel light beams by a lens, and then allowed to pass through a Faraday device, followed by being converged to an incident end of the optical fiber by a lens. The Faraday device is applied with a magnetic field in a direction of the optical axis thereof from a coil. Moreover, the Faraday device is applied with a magnetic field in a direction perpendicular to the optical axis by a pair of magnets. When an electric current flowing in a coil 74 is changed from I to -I, the direction of a synthesized magnetic field can be rotated. Therefore, by arbitrarily changing the electric current flowing in the coil, polarization of transmission light can be controlled.

Abstract: In a semiconductor laser apparatus of the invention, a laser beam emitted from a semiconductor laser is collimated by an optical leans, and is subsequently split by a beam splitter in two directions. One split laser beam component is focused on a first photodetector through an optical lens. The other laser beam component is incident on a Fabry-Perot resonator, and is changed in intensity thereby. The laser beam component is then focused on a photodetector through an optical lens. The Fabry-Perot resonator is integrally designed such that dielectric multilayer films are respectively deposited on both the end faces of a crystalized quartz bulk, which is shaped into a columnar shape extending in the C-axis direction, so as to form a pair of reflect filters. Since the bulk is made of crystalized quartz it is not easily influenced by changes in temperature.

Abstract: Process for removing nitrogen oxides from gaseous mixtures comprising the same. Ammonia in an amount excessive over the stoichiometric amount necessary for reducing the nitrogen oxides is introduced into a reaction zone containing a catalyst. Then, ammonia in a minimum amount necessary for reduction of the nitrogen oxides is introduced into the reaction zone.