Intracavity frequency-converted optically-pumped semiconductor laser with red-light output
View Patent ↗In a branched resonator OPS-laser arrangement, a combination of intra-cavity optical parametric generation and intra-cavity sum-frequency mixing provides output radiation in a range between about 550 nanometers about 700 nanometers from an OPS fundamental wavelength in a range between about 900 nm and about 1100 nm.
1. Optical apparatus comprising:
first and second resonators having first and second portions with the first resonator portions being coaxial and the second portions separate;
an OPS-structure located in the second portion of the first resonator;
an arrangement for delivering optical pump radiation to the OPS-structure such that laser radiation having a fundamental wavelength circulates in the first resonator;
a first optically nonlinear crystal located in the coaxial first portions of the first and second resonators and arranged for optical parametric division of a portion of the fundamental wavelength radiation into signal radiation and idler radiation portions, the signal radiation portion having a wavelength greater than the wavelength of the fundamental radiation and less than the wavelength of the idler radiation portion;
an optical arrangement for directing the signal radiation into the second portion of the second resonator such that signal radiation circulates in the second resonator;
a second optically nonlinear crystal located in the coaxial first portions of the first and second resonators and arranged for sum-frequency mixing circulating fundamental wavelength radiation and signal wavelength radiation to provide sum-frequency radiation; and
wherein the fundamental wavelength of the OPS-laser radiation is selected such that the sum-frequency radiation has a wavelength between about 550 nanometers and 700 nanometers.
2. The apparatus of claim 1 , wherein the fundamental wavelength radiation has a wavelength between about 900 nanometers and about 1100 nanometers.
3. The apparatus of claim 1 , wherein the second optically nonlinear crystal is a crystal of lithium triborate (LBO).
4. The apparatus of claim 1 , wherein the first optically nonlinear crystal is a crystal of potassium titanyl arsenate (KTA).
5. The apparatus of claim 4 , wherein the sum-frequency radiation has a wavelength of about 628 nanometers and the fundamental wavelength radiation has a wavelength of about 1064 nanometers.
6. The apparatus of claim 4 , wherein the sum-frequency radiation has a wavelength of about 575 nanometers and the fundamental wavelength radiation has a wavelength of about 980 nanometers.
7. The apparatus of claim 5 , wherein the first optically nonlinear crystal is a crystal of rubidium titanyl arsenate (RTA).
8. The apparatus of claim 1 , wherein the first optically nonlinear crystal has a first bandwidth for the parametric division and the second optically nonlinear crystal has a second bandwidth for the sum-frequency mixing and wherein the second bandwidth is greater than the first bandwidth.
9. The apparatus of claim 1 , wherein the optical arrangement for directing the signal radiation into the second portion of the second resonator is a pair of isoceles Brewster prisms.
10. The apparatus of claim 9 , wherein the prisms are LBO prisms having an apex angle of about 63.8 degrees.
11. Optical apparatus comprising:
first and second resonators having first and second portions with the first resonator portions being coaxial and the second portions separate;
an OPS-structure located in the second portion of the first resonator;
an arrangement for delivering optical pump radiation to the OPS-structure such that laser radiation having a fundamental wavelength circulates in the first resonator;
a first optically nonlinear crystal located in the coaxial first portions of the first and second resonators and arranged for optical parametric division of a portion of the fundamental wavelength radiation into signal radiation and idler radiation portions, the signal radiation portion having a wavelength greater than the wavelength of the fundamental radiation and less than the wavelength of the idler radiation portion, the first optically nonlinear crystal having a first bandwidth for the parametric division process;
an optical arrangement for directing the signal radiation into the second portion of the second resonator such that signal radiation circulates in the second resonator;
a second optically nonlinear crystal located in the coaxial first portions of the first and second resonators and arranged for sum-frequency mixing circulating fundamental wavelength radiation and signal wavelength radiation to provide sum-frequency radiation, the second optically nonlinear crystal having a second bandwidth for the sum-frequency mixing process the second bandwidth being greater than the first bandwidth; and
wherein the fundamental wavelength of the OPS-laser radiation is selected such that the sum-frequency radiation has a wavelength between about 550 nanometers and 700 nanometers.
12. The apparatus of claim 11 , wherein the fundamental wavelength radiation has a wavelength between about 900 nanometers and about 1100 nanometers.
13. The apparatus of claim 11 , wherein the second optically nonlinear crystal is a crystal of lithium triborate (LBO) and the first optically nonlinear crystal is a crystal of potassium titanyl arsenate (KTA).
14. The apparatus of claim 13 , wherein the sum-frequency radiation has a wavelength of about 628 nanometers and the fundamental wavelength radiation has a wavelength of about 1064 nanometers.
15. The apparatus of claim 13 , wherein the sum-frequency radiation has a wavelength of about 575 nanometers and the fundamental wavelength radiation has a wavelength of about 980 nanometers.
16. A method of generating optical radiation comprising the steps of:
generating laser radiation having a fundamental wavelength with a gain medium in the form of an optically pumped semiconductor (OPS);
circulating the fundamental wavelength radiation through a first optically nonlinear crystal arranged to divide a portion of the circulating fundamental wavelength radiation into signal wavelength and idler wavelength radiation portions in a parametric division process, the signal wavelength being longer than the fundamental wavelength and shorter than the idler wavelength, the first optically nonlinear crystal having a first bandwidth for the parametric division process; and
circulating the signal wavelength radiation and a remaining portion of the fundamental wavelength radiation through a second optically nonlinear crystal arranged to generate output radiation by sum-frequency mixing the fundamental wavelength and signal wavelength radiations, the second optically nonlinear crystal having a second bandwidth for the sum-frequency mixing process, the second bandwidth being greater than the first bandwidth.
17. The method of claim 16 , wherein the fundamental wavelength radiation has a wavelength between about 900 nanometers and about 1100 nanometers and the output radiation is between 550 nm and 700 nm.
18. The method of claim 16 , wherein the second optically nonlinear crystal is a crystal of lithium triborate (LBO) and the first optically nonlinear crystal is a crystal of potassium titanyl arsenate (KTA).
19. The method of claim 18 , wherein the sum-frequency radiation has a wavelength of about 628 nanometers and the fundamental wavelength radiation has a wavelength of about 1064 nanometers.
20. The method of claim 18 , wherein the sum-frequency radiation has a wavelength of about 575 nanometers and the fundamental wavelength radiation has a wavelength of about 980 nanometers.