Abstract: A solid state laser device according to the present invention comprises a pumping semiconductor laser 11 for oscillating a laser light as a pumping light, a collimator lens 12 for leading the laser light to parallel rays, a focusing lens 21 for focusing the laser light led to the parallel rays by the collimator lens 12 and leading the focused laser light to a laser medium 22, the laser medium 22 for absorbing the laser light and outputting a spontaneous emission light and an optical resonator 25 for confining the spontaneous emission light to make the laser light oscillated by an induced emission, wherein the solid state laser device includes a housing 10 for storing the a pumping semiconductor laser 11 and the collimator lens 12 in a state of positioning them on the same optical axis 16, and a housing 20 for housing the focusing lens 21, the laser medium 22 and the optical resonator 25 in a state of positioning them on the same optical axis, and the housings are detachable.

Abstract: An optical isolator having a combination of rutile plates or other birefringent crystals and Faraday elements. This optical isolator includes, arranged in the stated order along an optical axis, a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45.degree.; a second birefringent crystal having an optic axis rotated 45.degree. with respect to the first birefringent crystal, and a thickness .sqroot.2 times a thickness of the first birefringent crystal; a third birefringent crystal having an optic axis rotated 135.degree. with respect to the first birefringent crystal, and a thickness .sqroot.2 times the thickness of the first birefringent crystal; a second Faraday element for rotating the plane of polarization 45.degree.; and a fourth birefringent crystal having an optic axis rotated 180.degree. with respect to the first birefringent crystal, and a thickness equal to the thickness of the first birefringent crystal.

Abstract: A waveguide type optical circuit element having a directional coupler for converting light intensity between two waveguides, which is used as a polarity-independent optical switch or a variable optical divider for optical fiber communications and the like. The two waveguides (2), (3) have a coupling section length which is in a TE mode about three times a complete coupling length of the TE mode, and in a TM mode about one time a complete coupling length of the TM mode. Electrodes (4), (5) comprise three-part electrodes of different lengths which act as reverse .DELTA..beta. electrodes for alternately reversing a direction of an electric field. This construction promotes the light-confinement effect of the waveguides, reduces the drive voltage necessary for carrying out an optical switching operation, and realizes optimal element characteristics in accordance with a ratio of variations in the propagation coefficient in the TE mode and TM mode of the directional coupler manufactured.

Abstract: A flexible replica grating having a metal layer of a wave-like shape, a synthetic resin layer for supporting the metal layer, and a flexible synthetic resin film for supporting the synthetic resin layer.