Abstract: A wavelength converter which performs simultaneously wavelength conversion for a plurality of input light wavelengths that are unequally intervals, is provided. The nonlinear material of the wavelength converter has a modulation structure which has modulation of a nonlinear optical constant at a period ?0 in a propagating direction of light, a phase being continuously changed each period ?0 and a continuous phase modulation for a different period ?ph being added to the modulation structure. The nonlinear material has a modulation structure obtained by changing a modulation curve for the phase modulation, wherein a phase mismatch ?? is represented by ??=2?(n3/?3?n2/?2?n1/?1), and at least three peaks at unequally intervals within a plurality of peaks for conversion efficiency represented by 2?/?0+2?i/?f (i=m, m+1, . . . , n: where m and n are positive or negative integers) have highest conversion efficiency.

Abstract: A light source apparatus with modulation function has a wavelength conversion module (75) composed of a nonlinear optical material with a structure having a nonlinear constant modulated periodically. It outputs a difference frequency or sum frequency produced by multiplexing pumping light from semiconductor laser light sources (71) and (72) with different wavelengths through a WDM coupler (74) and by launching the multiplexed light into the optical waveguide. The semiconductor laser light source (72) includes a diffraction grating. The semiconductor laser light source (71) includes a section for modulating output light emitted from its semiconductor laser, and is connected to an external FBG (73) which has a reflection band narrower than a resonance wavelength spacing determined by the device length of the semiconductor laser. The FBG (73) is supplied with the modulated output.

Abstract: A light source apparatus with modulation function has a wavelength conversion module (75) composed of a nonlinear optical material with a structure having a nonlinear constant modulated periodically. It outputs a difference frequency or sum frequency produced by multiplexing pumping light from semiconductor laser light sources (71) and (72) with different wavelengths through a WDM coupler (74) and by launching the multiplexed light into the optical waveguide. The semiconductor laser light source (72) includes a diffraction grating. The semiconductor laser light source (71) includes a section for modulating output light emitted from its semiconductor laser, and is connected to an external FBG (73) which has a reflection band narrower than a resonance wavelength spacing determined by the device length of the semiconductor laser. The FBG (73) is supplied with the modulated output.

Abstract: A wavelength converter which performs simultaneously wavelength conversion for a plurality of input light wavelengths that are unequally intervals, is provided. The nonlinear material of the wavelength converter has a modulation structure which has modulation of a nonlinear optical constant at a period ?0 in a propagating direction of light, a phase being continuously changed each period ?0 and a continuous phase modulation for a different period ?ph being added to the modulation structure. The nonlinear material has a modulation structure obtained by changing a modulation curve for the phase modulation, wherein a phase mismatch ?? is represented by ??=2?(n3/?3?n2/?2?n1/?1), and at least three peaks at unequally intervals within a plurality of peaks for conversion efficiency represented by 2?/?0+2?i/?f (i=m, m+1, . . . , n: where m and n are positive or negative integers) have highest conversion efficiency.

Abstract: A laser light source is disclosed consisting of first and second lasers that respectively generate laser beams of wavelengths ?1 and ?2. Wavelength ?1 is in the range of 0.9-1.0 ?m. A nonlinear optical crystal uses the laser beams of wavelengths ?1 and ?2 as inputs, and outputs a coherent beam having a wavelength ?3 of a difference frequency that satisfies a relationship of 1/?1?1/?2=1/?3. The nonlinear optical crystal has a periodically poled structure of a single period. The wavelength ?3 of the difference frequency varies between 3.1 ?m and 2.0 ?m when the wavelength ?2 varies between 1.3 ?m and 1.8 ?m.

Abstract: The present invention provides a periodically-poled structure with high conversion efficiency and improved manufacturing yield. The method for manufacturing a periodically-poled structure in a second order nonlinear optical crystal having a single domain structure (31) includes the steps of forming a resist pattern (32) which matches a polarization-inverted period on a ?Z surface of the second order nonlinear optical crystal (31), and applying voltage to the ?Z surface as a negative voltage where the resist pattern (32) is formed, and a +Z surface as a positive voltage so as to apply an electric field in the second order nonlinear optical crystal (31), wherein the second order nonlinear optical crystal (31) contains at least one element as a dopant which compensate for the crystal defects.

Abstract: The invention provides a compact laser light source whose wavelength can be designed freely in a wavelength band in which the semiconductor laser has not been put to practical use by combining an efficient nonlinear optical crystal and high-power semiconductor lasers for optical communication. In one embodiment, the laser light source includes: a first laser for generating a laser beam of a wavelength ?1; a second laser for generating a laser beam of a wavelength ?2; and a nonlinear optical crystal that allows the laser beam of wavelength ?1 and the laser beam of wavelength ?2 as inputs and outputs a coherent beam having a wavelength ?3 of a sum frequency that satisfies a relationship of 1/?1+1/?2=1/?3. The wavelength ?3 of the sum frequency is 589.3±2 nm that is equivalent to the sodium D line.

Abstract: Disclosed is a belt conveyor capable of greatly reducing friction resistance between side portions of a belt and troughs, comprising troughs (5), a belt moving above the troughs (5) along a longitudinal direction thereof, belt bending members (12) provided outside on both sides of the belt in the width direction so as to be located upstream of an entrance (5a) of the troughs, for abutting with both side portions of the belt to be bent upwardly, load cells (14) for detecting a reactive force exerted by the belt with which the belt bending members (12) make contact, guide rails (16) engaged to cause the belt bending members (12) to be displaced to be fixed at a desired position so as to bend the side portions of the belt or restore the bent belt, and rails (20) for moving the guide rails (16) along the longitudinal direction of the belt.

Abstract: A laser light source is disclosed consisting of first and second lasers that respectively generate laser beams of wavelengths ?1 and ?2. Wavelength ?1 is in the range of 0.9-1.0 ?m. A nonlinear optical crystal uses the laser beams of wavelengths ?1 and ?2 as inputs, and outputs a coherent beam having a wavelength ?3 of a difference frequency that satisfies a relationship of 1/?1?1/?2=1/?3. The nonlinear optical crystal has a periodically poled structure of a single period. The wavelength ?3 of the difference frequency varies between 3.1 ?m and 2.0 ?m when the wavelength ?2 varies between 1.3 ?m and 1.8 ?m.

Abstract: Disclosed is a belt conveyor capable of greatly reducing friction resistance between side portions of a belt and troughs, comprising troughs (5), a belt moving above the troughs (5) along a longitudinal direction thereof, belt bending members (12) provided outside on both sides of the belt in the width direction so as to be located upstream of an entrance (5a) of the troughs, for abutting with both side portions of the belt to be bent upwardly, load cells (14) for detecting a reactive force exerted by the belt with which the belt bending members (12) make contact, guide rails (16) engaged to cause the belt bending members (12) to be displaced to be fixed at a desired position so as to bend the side portions of the belt or restore the bent belt, and rails (20) for moving the guide rails (16) along the longitudinal direction of the belt.

Abstract: Disclosed is a belt conveyor capable of greatly reducing friction resistance between side portions of a belt and troughs, comprising troughs (5), a belt moving above the troughs (5) along a longitudinal direction thereof, belt bending members (12) provided outside on both sides of the belt in the width direction so as to be located upstream of an entrance (5a) of the troughs, for abutting with both side portions of the belt to be bent upwardly, load cells (14) for detecting a reactive force exerted by the belt with which the belt bending members (12) make contact, guide rails (16) engaged to cause the belt bending members (12) to be displaced to be fixed at a desired position so as to bend the side portions of the belt or restore the bent belt, and rails (20) for moving the guide rails (16) along the longitudinal direction of the belt.

Abstract: Disclosed is a belt conveyor capable of greatly reducing friction resistance between side portions of a belt and troughs, comprising troughs (5), a belt moving above the troughs (5) along a longitudinal direction thereof, belt bending members (12) provided outside on both sides of the belt in the width direction so as to be located upstream of an entrance (5a) of the troughs, for abutting with both side portions of the belt to be bent upwardly, load cells (14) for detecting a reactive force exerted by the belt with which the belt bending members (12) make contact, guide rails (16) engaged to cause the belt bending members (12) to be displaced to be fixed at a desired position so as to bend the side portions of the belt or restore the bent belt, and rails (20) for moving the guide rails (16) along the longitudinal direction of the belt.

Abstract: The invention provides a compact laser light source whose wavelength can be designed freely in a wavelength band in which the semiconductor laser has not been put to practical use by combining an efficient nonlinear optical crystal and high-power semiconductor lasers for optical communication. In one embodiment, the laser light source includes: a first laser for generating a laser beam of a wavelength ?1; a second laser for generating a laser beam of a wavelength ?2; and a nonlinear optical crystal that allows the laser beam of wavelength ?1 and the laser beam of wavelength ?2 as inputs and outputs a coherent beam having a wavelength ?3 of a sum frequency that satisfies a relationship of 1/?1+1/?2=1/?3. The wavelength ?3 of the sum frequency is 589.3±2 nm that is equivalent to the sodium D line.

Abstract: Disclosed is a belt conveyor capable of greatly reducing friction resistance between side portions of a belt and troughs, comprising troughs (5), a belt moving above the troughs (5) along a longitudinal direction thereof, belt bending members (12) provided outside on both sides of the belt in the width direction so as to be located upstream of an entrance (5a) of the troughs, for abutting with both side portions of the belt to be bent upwardly, load cells (14) for detecting a reactive force exerted by the belt with which the belt bending members (12) make contact, guide rails (16) engaged to cause the belt bending members (12) to be displaced to be fixed at a desired position so as to bend the side portions of the belt or restore the bent belt, and rails (20) for moving the guide rails (16) along the longitudinal direction of the belt.

Abstract: A wavelength converter has a phase modulated periodically modulated structure, where a nonlinear optical coefficient is periodically modulated at a fundamental period &Lgr;0 and the phase of the modulation varies nearly continuously, and the phase variation of the modulation unit structure is repeated at a period &Lgr;ph (>&Lgr;0). A conversion efficiency is made maximum when a phase mismatch amount &Dgr;&bgr; equals 2&pgr;/&Lgr;0±2&pgr;i/&Lgr;ph (i=0, 1, . . . , n, where n is a positive integer), 2&pgr;/&Lgr;0±2&pgr;(2i+1)/&Lgr;ph (i=0, 1, . . . , n), or 2&pgr;/&Lgr;0+2&pgr;i/&Lgr;f (i=m, m+1, . . . .

Abstract: An optical fiber amplifier with a high conversion efficiency, which is capable of using the pump light in the wavelength band that can be emitted by the laser diode, is formed by an amplification optical fiber containing thulium at least in a core, to which a signal light is to be entered, and a pump light input unit configured to enter at least one pump light with a wavelength in a range of 1320-1520 nm, or more preferably 1320-1480 nm, into the amplification optical amplifier.

Abstract: Disclosed is a belt conveyor capable of greatly reducing friction resistance between side portions of a belt and troughs, comprising troughs (5), a belt moving above the troughs (5) along a longitudinal direction thereof, belt bending members (12) provided outside on both sides of the belt in the width direction so as to be located upstream of an entrance (5a) of the troughs, for abutting with both side portions of the belt to be bent upwardly, load cells (14) for detecting a reactive force exerted by the belt with which the belt bending members (12) make contact, guide rails (16) engaged to cause the belt bending members (12) to be displaced to be fixed at a desired position so as to bend the side portions of the belt or restore the bent belt, and rails (20) for moving the guide rails (16) along the longitudinal direction of the belt.

Abstract: A wavelength converter has a phase modulated periodically modulated structure, where a nonlinear optical coefficient is periodically modulated at a fundamental period &Lgr;0 and the phase of the modulation varies nearly continuously, and the phase variation of the modulation unit structure is repeated at a period &Lgr;ph (>&Lgr;0). A conversion efficiency is made maximum when a phase mismatch amount &Dgr;&bgr; equals 2&pgr;/&Lgr;0±2&pgr;i/&Lgr;ph (i=0, 1, . . . , n, where n is a positive integer), 2&pgr;/&Lgr;0±2&pgr;(2i+1)/&Lgr;ph (i=0, 1, . . . , n), or 2&pgr;/&Lgr;0+2&pgr;i/&Lgr;f (i=m, m+1, . . . .

Abstract: An optical fiber amplifier with a high conversion efficiency, which is capable of using the pump light in the wavelength band that can be emitted by the laser diode, is formed by an amplification optical fiber containing thulium at least in a core, to which a signal light is to be entered, and a pump light input unit configured to enter at least one pump light with a wavelength in a range of 1320-1520 nm, or more preferably 1320-1480 nm, into the amplification optical amplifier.

Abstract: This invention relates to fluoride glass with a specific composition having wide infrared transmission. A fluoride optical fiber using this fluoride glass can give high efficiency with a low loss. The fluoride optical fiber having a second cladding on the outer periphery of a first cladding can adjust the refractive index of the first cladding suitably.