Light source unit and light irradiation unit
In nonlinear optical crystal 183 D, each step of wavelength conversion can be performed using another fundamental wave that is output from light output unit 161 2 , without using the fundamental wave whose output level has been attenuated after going through wavelength conversion for several steps (wavelength conversion in nonlinear optical crystals 183 A to 183 C). Therefore, the wavelength conversion efficiency improves and the peak power of optical amplifiers 161 1 and 161 2 can be suppressed, which allows the wavelength of lights that are output from optical amplifiers 161 1 and 161 2 to be further narrowed.
1. A light source unit that generates light having a predetermined wavelength, said unit comprising:
a plurality of light output units that output lights having wavelengths different from said predetermined wavelength; and
a wavelength converter that generates light having said predetermined wavelength by wavelength conversion in a plurality of steps which include wavelength conversion using two lights as incident lights whose fundamental waves are severally output from different light output units of said plurality of light output units, wherein
at least one unit of said plurality of light output units is a first unit that outputs light of a first wavelength, and at least one unit of said plurality of light output units is a second unit that outputs light of a second wavelength different from light of said first wavelength,
wavelength conversion of said wavelength converter includes wavelength conversion in which the m-fold wave (m: natural number) of said light having the first wavelength output from said first unit and the n-fold wave (n: natural number) of said light having the second wavelength output from said second unit enter said converter to generate a sum-frequency of said m-fold wave and said n-fold wave,
one unit of said first unit and said second unit is in plurals, and
said wavelength conversion of said wavelength converter further includes wavelength conversion that generates a sum-frequency of said generated sum-frequency and light output from the other said one unit, which is not used for generating said sum-frequency.
2. The light source unit according to claim 1 , wherein at least one unit of said plurality of light output units is an optical fiber amplifier.
3. The light source unit according to claim 1 , wherein at least one unit of said plurality of light output units is an erbium doped optical fiber amplifier.
4. The light source unit according to claim 1 , wherein at least one unit of said plurality of light output units is an ytterbium doped optical fiber amplifier.
5. The light source unit according to claim 1 , wherein the wavelength of light input to said ytterbium doped optical fiber amplifier is longer than 1060 nm.
6. The light source unit according to claim 1 , wherein said wavelength converter generates light having a wavelength near 248 nm, which is approximately the same wavelength as the oscillation wavelength of a KrF excimer laser.
7. The light source unit according to claim 1 , wherein said wavelength converter generates light having a wavelength near 193 nm, which is approximately the same wavelength as the oscillation wavelength of an ArF excimer laser.
8. The light source unit according to claim 1 , wherein said wavelength converter generates light having a wavelength near 157 nm, which is approximately the same wavelength as the oscillation wavelength of an F 2 laser.
9. The light source unit according to claim 1 , wherein said wavelength converter performs wavelength conversion by using a plurality of nonlinear optical elements.
10. The light source unit according to claim 9 , wherein at least one nonlinear optical element of said plurality of nonlinear optical elements is an NH 4 H 2 PO 4 crystal.
11. The light source unit according to claim 9 , wherein at least one nonlinear optical element of said plurality of nonlinear optical elements is a quasi-phase-matching crystal.
12. The light source unit according to claim 11 , wherein at least one of a KTiOPO 4 crystal and an LiNbO 3 crystal is used as said quasi-phase-matching crystal.
13. The light source unit according to claim 11 , wherein a BaMgF 4 crystal is used as said quasi-phase-matching crystal.
14. The light source unit according to claim 13 , wherein said BaMgF 4 crystal generates the sum-frequency of said fundamental wave and an m-fold wave (m: natural number) of said fundamental wave.
15. The light source unit according to claim 1 , wherein a delay unit delays light propagation input from said units to said wavelength converter by a predetermined period of time.
16. The light source unit according to claim 15 , wherein said delay unit is inserted in between at least some units of said each light output unit and said wavelength converter.
17. The light source unit according to claim 1 , wherein said predetermined wavelength is 90 nm and over, up until 800 nm.
18. A light irradiation unit that irradiates light on an irradiation object, said unit comprising:
the light source unit of claim 1 ; and
an irradiation optical system that emits light emitted from said light source unit toward said irradiation object.
19. The light irradiation unit according to claim 18 , wherein said irradiation object is a photosensitive object.
20. A light source unit that generates light having a predetermined wavelength, said unit comprising:
a plurality of light output units that output lights having wavelengths different from said predetermined wavelength; and
a wavelength converter that generates light having said predetermined wavelength by wavelength conversion in a plurality of steps which include wavelength conversion using two lights as incident lights whose fundamental waves are severally output from different light output units of said plurality of light output units, wherein
at least one unit of said plurality of light output units is a first unit that outputs light of a first wavelength, and at least one unit of said plurality of light output units is a second unit that outputs light of a second wavelength different from light of said first wavelength, and
said first unit is an ytterbium doped optical fiber amplifier, and said second unit is at least one of an erbium doped optical fiber amplifier, a thulium doped optical fiber amplifier and a holmium doped optical fiber amplifier.