Abstract: A housing accommodates an optical waveguide substrate, plural signal light receiving elements, and a signal-light-level monitoring light receiving element. Signal light and locally oscillated light are input into optical waveguides in the optical waveguide substrate from a first end face of the optical waveguide substrate. The plural signal light receiving elements are disposed aligned on a side of a second end face opposite to a side of the first end face of the optical waveguide substrate. The signal-light-level monitoring light receiving element is disposed on a side of a third end face or a fourth end face between the first end face and the second end face of the optical waveguide substrate and at a position closer to the first end face than to the second end face.

Abstract: A housing accommodates an optical waveguide substrate, plural signal light receiving elements, and a signal-light-level monitoring light receiving element. Signal light and locally oscillated light are input into optical waveguides in the optical waveguide substrate from a first end face of the optical waveguide substrate. The plural signal light receiving elements are disposed aligned on a side of a second end face opposite to a side of the first end face of the optical waveguide substrate. The signal-light-level monitoring light receiving element is disposed on a side of a third end face or a fourth end face between the first end face and the second end face of the optical waveguide substrate and at a position closer to the first end face than to the second end face.

Abstract: A chromatic dispersion compensator of present invention includes a high-refractive-index VIPA plate, a three-dimensional mirror, and a control unit. The high-refractive-index VIPA plate is made of a material such as silicon having a refractive index higher than that of optical glass and is able to output incident lights toward different directions according to wavelength. The three-dimensional mirror reflects the light of each wavelength emitted from the high-refractive-index VIPA plate, at a predetermined position and returns the light to the VIPA plate. The control unit controls a temperature of the high-refractive-index VIPA plate at a constant level while controlling the position of the three-dimensional mirror corresponding to a chromatic dispersion compensation amount. Thereby, larger chromatic dispersion can be compensated while a decrease in transmission bandwidth is suppressed.

Abstract: A chromatic dispersion generating apparatus of the present invention comprises a VIPA plate capable of emitting an incident light to different directions according to wavelengths, a three-dimensional mirror reflecting the light of respective wavelengths emitted from the VIPA plate at a previously set position to return them to the VIPA plate, and a control section that controls a position of the three-dimensional mirror and the temperature of the VIPA plate.

Abstract: A dispersion compensator comprising a VIPA is configured so as to reflect light with each wavelength at an angle varying depending on wavelength when the light is reflected off a mirror. When being coupled at the end of an input fiber, the light with each wavelength is coupled at a specific angle. If the light is coupled with the fiber at a specific angle, coupling efficiency degrades. Therefore, in this case, coupling loss increases. Light having a wavelength with high transmittance in the VIPA is coupled with the fiber at a large angle, while light with a low transmittance is efficiently coupled with the fiber at a small angle or no angle. In this way, the round-top wavelength characteristic of the VIPA can be leveled.

Abstract: A chromatic dispersion compensator of present invention includes a high-refractive-index VIPA plate, a three-dimensional mirror, and a control unit. The high-refractive-index VIPA plate is made of a material such as silicon having a refractive index higher than that of optical glass and is able to output incident lights toward different directions according to wavelength. The three-dimensional mirror reflects the light of each wavelength emitted from the high-refractive-index VIPA plate, at a predetermined position and returns the light to the VIPA plate. The control unit controls a temperature of the high-refractive-index VIPA plate at a constant level while controlling the position of the three-dimensional mirror corresponding to a chromatic dispersion compensation amount. Thereby, larger chromatic dispersion can be compensated while a decrease in transmission bandwidth is suppressed.

Abstract: A chromatic dispersion generating apparatus of the present invention comprises a VIPA plate capable of emitting an incident light to different directions according to wavelengths, a three-dimensional mirror reflecting the light of respective wavelengths emitted from the VIPA plate at a previously set position to return them to the VIPA plate, and a control section that controls a position of the three-dimensional mirror and the temperature of the VIPA plate.

Abstract: A cabinet provided with light input/output holes accommodates a VIPA optical element, a lens, a fixing material fixing the VIPA optical element. A temperature-controlled heater controls the temperature of and inside the cabinet. Both the light input and output holes of the cabinet are blocked by the fixing material and the lens, respectively, so that temperature inside the cabinet is not influenced by the outside air.

Abstract: A stress correction film is applied to one side of a VIPA optical element provided with a multi-layer fully reflective film and an anti-reflective film on one surface of a transparent plate, and a semi-transparent multi-layer reflective film on the other surface, in order to adjust the unbalance between the respective stress of the multi-layer films on each surface. In other words, by applying a stress correction film, the unbalance between the respective stress of the multi-layer films on each surface of the VIPA optical element is corrected, and accordingly a VIPA optical element with low profile irregularity can be realized.

Abstract: A cabinet provided with light input/output holes accommodates a VIPA optical element, a lens, a fixing material fixing the VIPA optical element. A temperature-controlled heater controls the temperature of and inside the cabinet. Both the light input and output holes of the cabinet are blocked by the fixing material and the lens, respectively, so that temperature inside the cabinet is not influenced by the outside air.

Abstract: A dispersion compensator comprising a VIPA is configured so as to reflect light with each wavelength at an angle varying depending on wavelength when the light is reflected off a mirror. When being coupled at the end of an input fiber, the light with each wavelength is coupled at a specific angle. If the light is coupled with the fiber at a specific angle, coupling efficiency degrades. Therefore, in this case, coupling loss increases. Light having a wavelength with high transmittance in the VIPA is coupled with the fiber at a large angle, while light with a low transmittance is efficiently coupled with the fiber at a small angle or no angle. In this way, the round-top wavelength characteristic of the VIPA can be leveled.

Abstract: The present invention aims at providing a variable optical attenuator to achieve the reduction of the wavelength-dependency of the entire device, by optimizing the magneto-optical system of the variable optical attenuator by deliberating the wavelength-dependency of Faraday rotation angles. To this end, the variable optical attenuator according to the present invention comprises: a Faraday rotator for providing a variable Faraday rotation angle; and a polarizer and an analyzer arranged in front of and behind the Faraday rotator, respectively, wherein the angle formed between the optical axis of the analyzer and the optical axis of the polarizer is set such that the Faraday rotation angle at which the wavelength-dependency of the optical attenuation amount of the variable optical attenuator becomes the maximum, is brought to be substantially 0°, to thereby reduce the wavelength-dependency of the optical attenuation amount at the aforementioned Faraday rotation angle.