Laser light source
View Patent ↗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 λ 1 ; a second laser for generating a laser beam of a wavelength λ 2 ; and a nonlinear optical crystal that allows the laser beam of wavelength λ 1 and the laser beam of wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 . The wavelength λ 3 of the sum frequency is 589.3±2 nm that is equivalent to the sodium D line.
1. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the second laser is a semiconductor laser and the first laser oscillates in a multimode,
wherein the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm,
wherein the polarization maintaining fiber coupled to the output of the first laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the first laser and the fiber Bragg grating are configured as a resonator structure, and
wherein the wavelength λ 3 of a sum frequency is a wavelength of 589.3±2 nm that is equivalent to the sodium D line.
2. The laser light source according to claim 1 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
3. The laser light source according to claim 2 , wherein, the nonlinear optical crystal has a waveguide structure.
4. The laser light source according to claim 1 , wherein, the wavelength λ 1 is 976±10 nm and the wavelength λ 2 is 1485±20 nm.
5. The laser light source according to claim 1 , wherein, the wavelength λ 1 is 1064±10 nm and the wavelength λ 2 is 1320±20 nm.
6. The laser light source according to claim 1 , wherein, the wavelength λ 1 is 940±10 nm and the wavelength λ 2 is 1565±35 nm.
7. The laser light source according to claim 4 , wherein the second laser for outputting a wavelength λ 2 =1485±20 nm is a DFB laser.
8. The laser light source according to claim 5 , wherein the second laser for outputting a wavelength λ 3 =1320±20 nm is a DFB laser.
9. The laser light source according to claim 6 , wherein the second laser for outputting a wavelength λ 2 =1565±35 nm is a DFB laser.
10. The laser light source according to claim 1 , wherein at least one of the first and second lasers has a first facet that is coupled to the polarization maintaining fiber and a second facet opposite to the first facet, the first facet being specified to have a reflectance of 2% or less and the second facet being specified to have a reflectance of 90% or more.
11. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the second laser is a semiconductor laser and the first laser oscillates in a multimode,
wherein the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm,
wherein the polarization maintaining fiber coupled to the output of the first laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the first laser and the fiber Bragg grating are configured as a resonator structure, and
wherein the wavelength λ 1 is 940±10 nm, the wavelength λ 2 is 1320±20 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 546.1±5.0 nm corresponding to a yellow range.
12. The laser light source according to claim 11 , wherein, representing refractive indices at the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
13. The laser light source according to claim 12 , wherein the nonlinear optical crystal has a waveguide structure.
14. The laser light source according to claim 11 , wherein the second laser is a DFB laser.
15. The laser light source according to claim 11 , wherein at least one of the first and second lasers has a first facet that is coupled to the polarization maintaining fiber and a second facet opposite to the first facet, the first facet being specified to have a reflectance of 2% or less and the second facet being specified to have a reflectance of 90% or more.
16. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the second laser is a semiconductor laser and the first laser oscillates in a multimode,
wherein the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm,
wherein the polarization maintaining fiber coupled to the output of the first laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the first laser and the fiber Bragg grating are configured as a resonator structure, and
wherein the wavelength λ 1 is 980±10 nm, the wavelength λ 2 is 1320±20 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 560.0±5.0 nm corresponding to a yellow range.
17. The laser light source according to claim 16 , wherein, representing refractive indices at the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
18. The laser light source according to claim 17 , wherein the nonlinear optical crystal has a waveguide structure.
19. The laser light source according to claim 16 , wherein the second laser is a DFB laser.
20. The laser light source according to claim 16 , wherein at least one of the first and second lasers has a first facet that is coupled to the polarization maintaining fiber and a second facet opposite to the first facet, the first facet being specified to have a reflectance of 2% or less and the second facet being specified to have a reflectance of 90% or more.
21. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of a wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the second laser is a semiconductor laser and the first laser oscillates in a multimode,
wherein the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm,
wherein the polarization maintaining fiber coupled to the output of the first laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the first laser and the fiber Bragg grating are configured as a resonator structure, and
wherein the wavelength λ 1 is 1064±10 nm, the wavelength λ 2 is 1320±20 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 585.0±5.0 nm corresponding to a yellow range.
22. The laser light source according to claims 21 , wherein, representing refractive indices at the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
23. The laser light source according to claim 22 , wherein the nonlinear optical crystal has a waveguide structure.
24. The laser light source according to claim 21 , wherein the second laser is a DFB laser.
25. The laser light source according to claim 21 , wherein at least one of the first and second lasers has a first facet that is coupled to the polarization maintaining fiber and a second facet opposite to the first facet, the first facet being specified to have a reflectance of 2% or less and the second facet being specified to have a reflectance of 90% or more.
26. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the second laser is a semiconductor laser and the first laser oscillates in a multimode,
wherein the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm,
wherein the polarization maintaining fiber coupled to the output of the first laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the first laser and the fiber Bragg grating are configured as a resonator structure, and
wherein the wavelength λ 1 is 940±10 nm, the wavelength λ 2 is 1550±30 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 585.0±5.0 nm corresponding to a yellow range.
27. The laser light source according to claim 26 , wherein, representing refractive indices at the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
28. The laser light source according to claim 27 , wherein the nonlinear optical crystal has a waveguide structure.
29. The laser light source according to claim 26 , wherein the second laser is a DFB laser.
30. The laser light source according to claim 26 , wherein at least one of the first and second lasers has a first facet that is coupled to the polarization maintaining fiber and a second facet opposite to the first facet, the first facet being specified to have a reflectance of 2% or less and the second facet being specified to have a reflectance of 90% or more.
31. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation,
the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 976±10 nm, the wavelength λ 2 is 1485±20 nm, the wavelength λ 3 of a sum frequency is a wavelength of 589.3±2 nm that is equivalent to the sodium D line.
32. The laser light source according to claim 31 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
33. The laser light source according to claim 32 , wherein, the nonlinear optical crystal has a waveguide structure.
34. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation,
the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 1064±10 nm, the wavelength λ 2 is 1320±20 nm, the wavelength λ 3 of a sum frequency is a wavelength of 589.3±2 nm that is equivalent to the sodium D line.
35. The laser light source according to claim 34 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
36. The laser light source according to claim 35 , wherein, the nonlinear optical crystal has a waveguide structure.
37. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation, the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 940±10 nm, the wavelength λ 2 is 1565±35 nm, the wavelength λ 3 of a sum frequency is a wavelength of 589.3±2 nm that is equivalent to the sodium D line.
38. The laser light source according to claim 37 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
39. The laser light source according to claim 38 , wherein, the nonlinear optical crystal has a waveguide structure.
40. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation,
the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 940±10 nm, the wavelength λ 2 is 1320±20 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 546.1±5.0 nm corresponding to a yellow range.
41. The laser light source according to claim 40 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
42. The laser light source according to claim 41 , wherein, the nonlinear optical crystal has a waveguide structure.
43. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation,
the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 980±10 nm, the wavelength λ 2 is 1320±20 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 560.0±5.0 nm corresponding to a yellow range.
44. The laser light source according to claim 43 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
45. The laser light source according to claim 44 , wherein, the nonlinear optical crystal has a waveguide structure.
46. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation,
the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 1064±10 nm, the wavelength λ 2 is 1320±20 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 585.0±5.0 nm corresponding to a yellow range.
47. The laser light source according to claim 46 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
48. The laser light source according to claim 47 , wherein, the nonlinear optical crystal has a waveguide structure.
49. A laser light source comprising a first laser for generating a laser beam of a wavelength λ 1 , a second laser for generating a laser beam of a wavelength λ 2 , and a nonlinear optical crystal that uses the laser beam of the wavelength λ 1 and the laser beam of the wavelength λ 2 as inputs and outputs a coherent beam having a wavelength λ 3 of a sum frequency that satisfies a relationship of 1/λ 1 +1/λ 2 =1/λ 3 , comprising:
two polarization maintaining fibers coupled to outputs of the first and second lasers, respectively; and
a multiplexer for multiplexing outputs of the two polarization maintaining fibers and coupling a multiplexed output to the nonlinear optical crystal,
wherein the first laser is a semiconductor laser in a single mode oscillation,
the second laser is a DFB laser,
the polarization maintaining fiber coupled to the second laser has a fiber Bragg grating with a full width of half maximum of 0.5 or less and the second laser and the fiber Bragg grating are configured as a resonator structure,
the nonlinear optical crystal has a periodically poled structure and a length of the nonlinear optical crystal is 10-60 mm, and
the wavelength λ 1 is 940±10 nm, the wavelength λ 2 is 1550±30 nm, and the wavelength λ 3 of the sum frequency is a wavelength of 585.0±5.0 nm corresponding to a yellow range.
50. The laser light source according to claim 49 , wherein, representing refractive indices of the wavelengths λ 1 , λ 2 , and λ 3 by n 1 , n 2 , and n 3 , respectively, the nonlinear optical crystal has a periodically poled structure of a period Λ that satisfies
2πn 3 /λ 3 =2πn 1 /λ 1 +2πn 2 /λ 2 +2πn 2 /Λ.
51. The laser light source according to claim 50 , wherein, the nonlinear optical crystal has a waveguide structure.