Drive laser for EUV light source
View Patent ↗A device is described herein which may comprise an oscillator having an oscillator cavity length, L o , and defining an oscillator path; and a multi-pass optical amplifier coupled with the oscillator to establish a combined optical cavity including the oscillator path, the combined cavity having a length, L combined , where L combined =(N+x)*L o , where “N” is an integer and “x” is a number between 0.4 and 0.6.
1. A device comprising:
a first laser source producing a first output beam having a wavelength, λ l ,
a second laser source producing a second output beam having a wavelength, λ 2 , with, λ 1 ≠λ 2 ,
an amplifier having a gain band including λ 1 and λ 2 , wherein said amplifier comprises a plurality of amplifier chambers positioned along a common beam path
an optical isolator having a polarization discriminating optic substantially transmitting light having a first linear polarization and substantially blocking transmission of light having a linear polarization orthogonal to said first polarization;
a coupling optic having a transmission-reflection ratio, TRR 1 , for light having a wavelength, λ 1 , and a transmission-reflection ratio, TRR 2 , for light having a wavelength, λ 2 , with TRR 1 ≠TRR 2 , the optic coupling the first output beam and second output beam onto a common beam path through the amplifier, and wherein said coupling optic is positioned between two amplifier chambers on the common beam path.
2. A device as recited in claim 1 wherein said first laser source has a gain medium comprising CO 2 producing a first output beam having a wavelength, λ 1 of 9.3 μm and the second laser source has a gain medium comprising CO 2 producing a second output beam having a wavelength, λ 2 , of 10.6 μm.
3. A device as recited in claim 1 wherein said optical isolator comprises a forty-five degree phase retarding optic and a linear polarization filter.
4. A device as recited in claim 1 wherein said device is a drive laser for a laser-produced-plasma (LPP) extreme-ultraviolet (EUV) light source.
5. A device as recited in claim 4 wherein said first laser source produces a train of pre-pulses and said second laser source produces a train of main pulses.
6. A device as recited in claim 1 wherein at least one of said first and second laser sources comprises a Q-switched, pulsed, oscillator.
7. A device as recited in claim 1 wherein said amplifier has a gain, G, greater than 1000.
8. A device as recited in claim 1 wherein said coupling optic comprises a thin film polarizer element having a first side optimized for reflection of λ 2 , and a second side coated with an anti-reflective coating for reducing reflections of λ 1 .
9. A device comprising:
a first means producing a first output beam having a wavelength, λ l ,
a second means producing a second output beam having a wavelength, λ 2 , with, λ 1 ≠λ 2 ,
an amplifying means having a gain band including λ 1 and λ 2 , wherein said amplifying means comprises a plurality of amplifier chambers positioned along a common beam path;
an isolator means having a polarization discriminating optic substantially transmitting light having a first linear polarization and substantially blocking transmission of light having a linear polarization orthogonal to said first polarization;
a coupling means having a transmission-reflection ratio, TRR 1 , for light having a wavelength, λ 1 , and a transmission-reflection ratio, TRR 2 , for light having a wavelength, λ 2 , with TRR 1 ≠TRR 2 , and coupling the first output beam and second output beam onto a common beam path through the amplifying means, and wherein said coupling means is positioned between two amplifier chambers on the common beam path.
10. A device as recited in claim 9 wherein said first means has a gain medium comprising CO 2 producing a first output beam having a wavelength, λ 1 of 9.3 μm and the second means has a gain medium comprising CO 2 producing a second output beam having a wavelength, λ 2 , of 10.6 μm.
11. A device as recited in claim 9 wherein said isolator means comprises a forty-five degree phase retarding optic and a linear polarization filter.
12. A device as recited in claim 9 wherein said device is a drive laser for a laser-produced-plasma (LPP) extreme-ultraviolet (EUV) light source.
13. A device as recited in claim 12 wherein said first means produces a train of pre-pulses and said second means produces a train of main pulses.
14. A device as recited in claim 9 wherein at least one of said first and second means comprises a Q-switched, pulsed, oscillator.
15. A device as recited in claim 9 wherein said amplifying means has a gain, G, greater than 1000.
16. A device as recited in claim 9 wherein said coupling means comprises a thin film polarizer element having a first side optimized for reflection of λ 1 and a second side coated with an anti-reflective coating for reducing reflections of λ 2 .
17. A method comprising the steps of:
producing a first output beam having a wavelength, λ 1 ,
producing a second output beam having a wavelength, λ 2 , with, λ 1 ≠λ 2 ,
providing an amplifier having a gain band including λ 1 and λ 2 , wherein said amplifier comprises a plurality of amplifier chambers positioned along a common beam path;
providing an isolator having a polarization discriminating optic substantially transmitting light having a first linear polarization and substantially blocking transmission of light having a linear polarization orthogonal to said first polarization;
coupling the first output beam and second output beam onto a common beam path through the amplifier using a coupling optic having a transmission-reflection ratio, TRR 1 , for light having a wavelength, λ 1 , and a transmission-reflection ratio, TRR 2 , for light having a wavelength, λ 2 , with TRR 1 ≠TRR 2 , and wherein said coupling optic is positioned between two amplifier chambers on the common beam path.
18. A method as recited in claim 17 wherein said first output beam has a wavelength, λ 1 of 9.3 μm and the second output beam has a wavelength, λ 2 , of 10.6 μm.
19. A method as recited in claim 17 wherein said amplifier has a gain, G, greater than 1000.
20. A method as recited in claim 17 wherein said coupling optic comprises a thin film polarizer element having a first side optimized for reflection of λ 2 , and a second side coated with an anti-reflective coating for reducing reflections of λ 1 .