Abstract: The inclination of a reflecting surface of a mirror is adjusted such that light outputted from an input optical fiber is reflected by the mirror so as to be fed into an output optical fiber. The normal direction of the reflecting surface of the mirror vibrates about a predetermined direction at a predetermined frequency. A part of the light propagating through the output optical fiber is taken out by a light-branching part, so as to be received by a photodiode, whereby an electric signal having a value corresponding to thus received quantity of light is outputted from a detection circuit. Whether or not the electric signal includes a component of the predetermined frequency or whether the component is strong or weak is detected, whereby whether or not there is optical coupling from the input optical fiber to the output optical fiber or the extent thereof is determined.

Abstract: The present invention provides a diffraction grating element that allows the temperature control mechanism to be dispensed with or simplified. The diffraction grating element of the present invention comprises a transparent plate having a first surface and a second surface that are substantially parallel with one another; and a diffraction grating which is formed on a first surface side with respect to the second surface and is substantially parallel with the first surface. At any temperature within a temperature range ?20° C. to +80° C., the sum of the rate of change in the period per unit length of the diffraction grating with respect to a temperature change, and the temperature coefficient of the refractive index of a medium that surrounds the diffraction grating element is 0.

Abstract: The present invention relates to an optical amplifier (TDFA) having a configuration which enables to reduce temperature dependence of the gain with reduced power consumption and simple control. The optical amplifier includes, in the order from an input port to an output port, an optical isolator, an optical coupler, an optical amplification fiber, an optical coupler, an optical isolator, an optical gain equalizing filter, a variable optical attenuator, an optical isolator, an optical coupler, an amplification fiber, an optical coupler, and an optical isolator. At least a core region of the optical amplification fiber is doped with Tm element, and signal light in a predetermined wavelength range is amplified by supply of pumping light. The gain equalizing fiber has a loss spectrum which shifts toward the short wavelength side as the temperature of the optical waveguide is higher, thereby equalizing the optical amplification gain of the signal light in the optical amplification fiber.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1-n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1–n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: The present invention relates to an optical component and the like having a structure that can increase the absolute value of the angular dispersion, and also can reduce the temperature dependence of the diffraction angle. The optical component comprises a diffraction grating element of a transmissive type and a prism. The prism is composed of a material with a refractive index of n1, and the diffraction grating element and the prism are surrounded a material with a refractive index of n0.

Abstract: To provide an optical signal processor which can perform favorable optical signal processing even when there are environmental changes and the like. An optical signal processor 1 inputs light emitted from an end face of an optical fiber 11, subjects the inputted light to processing according to its wavelength, and outputs the processed light so as to make it incident on the end face of the optical fiber 11; and comprises optical systems 111 to 113, a diffraction grating device 120, reflecting mirrors 131 to 133, an optical path turning part 140, and a monitor part 150. The optical path turning part 140 transmits therethrough a part of the incident light and reflects at least a part of the remnant. The optical system 113 monitors the light transmitted through the optical path turning part 140.

Abstract: The present invention provides a diffraction grating element that allows the temperature control mechanism to be dispensed with or simplified. The diffraction grating element of the present invention comprises a transparent plate having a first surface and a second surface that are substantially parallel with one another; and a diffraction grating which is formed on a first surface side with respect to the second surface and is substantially parallel with the first surface. At any temperature within a temperature range ?20° C. to +80° C., the sum of the rate of change in the period per unit length of the diffraction grating with respect to a temperature change, and the temperature coefficient of the refractive index of a medium that surrounds the diffraction grating element is 0.

Abstract: The present invention is directed to a gain equalizer having a preferable equalization characteristic and a structure that can be easily fabricated. The gain equalizer flattens a spectrum of light in a predetermined wavelength range inputted through an input terminal and outputs the light from an output terminal, and comprises a coarse-tunable equalizing section and a fine-tunable equalizing section connected in series. The coarse-tunable equalizing section coarsely flattens the spectrum of the light in the predetermined wavelength range, and includes a plurality of filters each having a large loss and a small reflectance as compared with the fine-tunable equalizing section. The fine-tunable equalizing section flattens the spectrum of the light in a wavelength range where the coarse-tunable equalizing section can not flatten at a predetermined value or less among the predetermined wavelength range.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1-n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: The present invention provides a diffraction grating element that allows the temperature control mechanism to be dispensed with or simplified. The diffraction grating element of the present invention comprises a transparent plate having a first surface and a second surface that are substantially parallel with one another; and a diffraction grating which is formed on a first surface side with respect to the second surface and is substantially parallel with the first surface. At any temperature within a temperature range ?20° C. to +80° C., the sum of the rate of change in the period per unit length of the diffraction grating with respect to a temperature change, and the temperature coefficient of the refractive index of a medium that surrounds the diffraction grating element is 0.

Abstract: The present invention relates to an optical component and the like having a structure that can increase the absolute value of the angular dispersion, and also can reduce the temperature dependence of the diffraction angle. The optical component comprises a diffraction grating element of a transmissive type and a prism. The prism is composed of a material with a refractive index of n1, and the diffraction grating element and the prism are surrounded a material with a refractive index of n0.

Abstract: An optical signal, which is to become the subject of dispersion compensation, is split by optical combining/splitting unit 2, and each frequency component of the optical signal that is split is reflected by the corresponding reflective mirror 30 included in reflective mirror group 3 to apply a predetermined phase shift to the respective frequency components Each reflected frequency component is then combined using optical combining/splitting unit 2, to give dispersion compensated optical signal Furthermore, in regards to reflective mirror group 3, which is used to apply phase shift to each frequency component of an optical signal, each of the respective plurality of reflective mirrors 30 is made a movable mirror having a movable reflection position that reflects the frequency components. Through this, dispersion that develops in an optical signal may be compensated with favorable controllability and high accuracy.

Abstract: The present invention relates to an optical amplifier (TDFA) having a configuration which enables to reduce temperature dependence of the gain with reduced power consumption and simple control. The optical amplifier includes, in the order from an input port to an output port, an optical isolator, an optical coupler, an optical amplification fiber, an optical coupler, an optical isolator, an optical gain equalizing filter, a variable optical attenuator, an optical isolator, an optical coupler, an amplification fiber, an optical coupler, and an optical isolator. At least a core region of the optical amplification fiber is doped with Tm element, and signal light in a predetermined wavelength range is amplified by supply of pumping light. The gain equalizing fiber has a loss spectrum which shifts toward the short wavelength side as the temperature of the optical waveguide is higher, thereby equalizing the optical amplification gain of the signal light in the optical amplification fiber.

Abstract: The present invention relates to a pumping light source unit for Raman amplification and the like comprising a structure for improving the pumping light spectrum controllability so as to enable output signal light spectrum adjustment within an amplification wavelength band. The pumping light source unit comprises N (?2) pumping light sources for outputting N channels of pumping light having respective wavelengths different from each other, a multiplexer for multiplexing the N channels of pumping light, and an output structure for supplying a Raman amplification optical fiber with the pumping light outputted from the multiplexer. In particular, at least one of the N pumping light sources includes a variable length pumping light source adapted to change the channel wavelength of pumping light outputted therefrom. This configuration makes it possible to adjust pumping light spectra, thereby improving the controllability of output signal light spectra (Raman gain spectra).

Abstract: The inclination of a reflecting surface of a mirror is adjusted such that light outputted from an input optical fiber is reflected by the mirror so as to be fed into an output optical fiber. The normal direction of the reflecting surface of the mirror vibrates about a predetermined direction at a predetermined frequency. A part of the light propagating through the output optical fiber is taken out by a light-branching part, so as to be received by a photodiode, whereby an electric signal having a value corresponding to thus received quantity of light is outputted from a detection circuit. Whether or not the electric signal includes a component of the predetermined frequency or whether the component is strong or weak is detected, whereby whether or not there is optical coupling from the input optical fiber to the output optical fiber or the extent thereof is determined.

Abstract: The present invention provides an optical fiber equipped with a grating that functions as a narrow-band loss filter. The optical fiber has a core, an inner cladding, an intermediate cladding, and an outer cladding, which have refractive indexes n0, n1, n2, and n3, respectively, the refractive indexes having a relationship of n0>n3?n1n2. At least a part of the inner cladding has a grating. The refractive index of the intermediate cladding is lower than the refractive indexes of the inner cladding and the outer cladding such that a recession is formed in the refractive index profile of the clad. The grating is provided on the inner side relative to the recession.

Abstract: The present invention relates to an optical signal processor which can multiplex or demultiplex multiwavelength signal light. The optical signal processor includes an optical input/output capability, a first optical system, a wavelength branching capability, a second optical system, and a reflecting capability.

Abstract: The present invention relates to an optical multiplexer/demultiplexer. In the multiplexer/demultiplexer, a first grating receives to diffract a multi-wavelength light signal from a first port into light signals with different wavelengths. A second grating diffracts these light signals towards second ports. The second grating is disposed parallel with the first grating. The second grating has the same grating interval and grating direction as the first grating. The light signals diffracted by the second grating travel parallel with each other. Therefore, the light signals can efficiently enter the second ports without sophisticated lens design and adjustment of the optical system.

Abstract: The present invention relates to an optical amplifier (TDFA) having a configuration which enables to reduce temperature dependence of the gain with reduced power consumption and simple control. The optical amplifier includes, in the order from an input port to an output port, an optical isolator, an optical coupler, an optical amplification fiber, an optical coupler, an optical isolator, an optical gain equalizing filter, a variable optical attenuator, an optical isolator, an optical coupler, an amplification fiber, an optical coupler, and an optical isolator. At least a core region of the optical amplification fiber is doped with Tm element, and signal light in a predetermined wavelength range is amplified by supply of pumping light. The gain equalizing fiber has a loss spectrum which shifts toward the short wavelength side as the temperature of the optical waveguide is higher, thereby equalizing the optical amplification gain of the signal light in the optical amplification fiber.