Intracavity frequency-converted optically-pumped semiconductor optical parametric oscillator
View Patent ↗In a branched resonator OPS-laser arrangement, a combination of intra-cavity optical parametric generation and intra-cavity frequency conversion provides output radiation in a range between about 550 nanometers about 800 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;
a light source 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-wavelength 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; and
a second optically nonlinear crystal located in the second resonator, the second optically nonlinear crystal being arranged for frequency-converting circulating signal radiation to a wavelength shorter than the wavelength of the circulating fundamental wavelength radiation.
2. The apparatus of claim 1 , wherein the second optically nonlinear crystal is located in the first portion of the second resonator and the frequency-conversion of the circulating signal radiation is effected by sum-frequency mixing of the circulating signal radiation with the circulating fundamental-wavelength radiation.
3. The apparatus of claim 1 , wherein the second optically nonlinear crystal is located in the first portion of the second resonator and the frequency-conversion of the circulating signal radiation is effected by frequency-doubling the circulating signal radiation.
4. The apparatus of claim 1 , wherein the second optically nonlinear crystal is located in the second portion of the second resonator and the frequency-conversion of the circulating signal radiation is effected by frequency-doubling the circulating signal radiation.
5. The apparatus of claim 1 , wherein the fundamental wavelength radiation has a wavelength between about 900 nanometers and about 1100 nanometers.
6. The apparatus of claim 1 , wherein the second optically nonlinear crystal is a crystal of lithium triborate (LBO).
7. The apparatus of claim 1 , wherein the first optically nonlinear crystal is a crystal of potassium titanyl arsenate (KTA).
8. The apparatus of claim 7 , wherein the fundamental wavelength radiation has a wavelength of about 1064 nanometers and the frequency-doubled.
9. 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 frequency-conversion and wherein the second bandwidth is greater than the first bandwidth.
10. 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 isosceles Brewster prisms.
11. The apparatus of claim 10 , wherein the prisms are LBO prisms having an apex angle of about 63.8 degrees.
12. 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;
a light source 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-wavelength 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 second resonator, the second optically nonlinear crystal being arranged for frequency-doubling circulating signal radiation to a wavelength shorter than the wavelength of the circulating fundamental wavelength radiation.
13. The apparatus of claim 12 , wherein the second optically nonlinear crystal is located in the first portion of the second resonator.
14. The apparatus of claim 12 , wherein the second optically nonlinear crystal is located in the second portion of the second resonator.
15. The apparatus of claim 11 , wherein the fundamental-wavelength radiation has a wavelength between about 900 nanometers and about 1100 nanometers.
16. The apparatus of claim 15 , wherein the fundamental-wavelength radiation has a wavelength of about 1064 nm and the frequency-doubled signal radiation has a wavelength of about 766 nm.
17. The apparatus of claim 12 , wherein the second optically nonlinear crystal is a crystal of lithium triborate (LBO).
18. The apparatus of claim 12 , wherein the first optically nonlinear crystal is a crystal of potassium titanyl arsenate (KTA).
19. 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, the signal wavelength being longer than the fundamental wavelength and shorter than the idler wavelength; and
circulating the signal-wavelength radiation through a second optically nonlinear crystal arranged to generate output-radiation by frequency-converting the signal radiation.
20. The method of claim 19 , wherein the signal radiation is frequency-converted by frequency doubling.
21. The method of claim 20 , wherein the fundamental wavelength is 1064 nm and the output radiation has a wavelength of 766 nm.