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 light source is provided that realizes a single spectral linewidth having a half value width of 1 MHz or less and that is not influenced by the ambient temperature. A light source includes first laser (71) generating first laser light, second laser (12) generating second laser light, and nonlinear optical crystal (13) wherein the first laser light and the second laser light are injected into the nonlinear optical crystal to generate coherent light by the generation of a difference frequency or a sum frequency. The second laser (12) is a wavelength-tunable light source that includes therein a diffraction grating and that can sweep the wavelength of the second laser light. The first laser (71) is composed of semiconductor laser and a fiber grating that has a reflection bandwidth narrower than a resonance wavelength spacing determined by the laser chip length of the semiconductor laser.

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: 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 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: A water-repellent coating has tetrafluoroethylene resin powder, silicone resin binder, and organic solvent. The tetrafluoroethylene resin powder has a ratio of the peak absorbance at 1,800 cm−1 to the peak absorbance at 500 cm−1 of 0.0001 to 0.05 exclusive. A coating film is formed by applying such a coating on a substrate. The coating has the properties of high water repellency, excellent anti-ice-coating, excellent anti-snow-coating, and so on, in spite of not having a large amount of fluororesin powder. In addition, the coating of film keeps the water repellency regardless of whether the coating film is immersed into water for a long time.

Abstract: A water-repellent coating has tetrafluoroethylene resin powder, silicone resin binder, and organic solvent. The tetrafluoroethylene resin powder has a ratio of the peak absorbance at 1,800 cm−1 to the peak absorbance at 500 cm −1 of 0.0001 to 0.05 exclusive. A coating film is formed by applying such a coating on a substrate. The coating has the properties of high water repellency, excellent anti-ice-coating, excellent anti-snow-coating, and so on, in spite of not having a large amount of fluororesin powder. In addition, the coating of film keeps the water repellency regardless of whether the coating film is immersed into water for a long time.