Method and device for generating pulsed laser radiation
A method for generating stabilized, pulsed laser radiation is disclosed, the method including at least the steps of generating pulsed laser radiation at a repetition frequency, wherein the spectrum of the pulsed laser radiation is a frequency comb having a number of equidistant spectral lines; deriving a first controlled variable from the pulsed laser radiation by means of phase comparison with a high-frequency reference signal; generating narrow-band continuous-wave laser radiation at a reference wavelength; setting the reference wavelength in accordance with a first manipulated variable derived from the first controlled variable; deriving a second controlled variable by means of superposition of the pulsed laser radiation and the continuous-wave laser radiation; and setting the repetition frequency in accordance with a second manipulated variable derived from the second controlled variable. A device for generating stabilized, pulsed laser radiation compatible with the method is also disclosed.
1. A method for generating stabilized, pulsed laser radiation, comprising the following method steps:
generating pulsed laser radiation at a repetition frequency, wherein the spectrum of the pulsed laser radiation is a frequency comb having a number of equidistant spectral lines,
deriving a first controlled variable from the pulsed laser radiation by means of phase comparison with a high-frequency reference signal,
generating narrow-band continuous-wave laser radiation at a reference wavelength,
setting the reference wavelength in accordance with a first manipulated variable derived from the first controlled variable,
deriving a second controlled variable by means of superposition of the pulsed laser radiation and the continuous-wave laser radiation, and
setting the repetition frequency in accordance with a second manipulated variable derived from the second controlled variable.
2. The method according to claim 1 , wherein the high-frequency reference signal is stabilized by means of locking to a frequency standard.
3. The method according to claim 1 , wherein a line width of the continuous-wave laser radiation is less than 10 kHz.
4. The method according to claim 1 , wherein a carrier-envelope offset frequency of the pulsed laser radiation is zero.
5. The method according to claim 1 , further comprising the following further method steps:
deriving a third controlled variable from the pulsed laser radiation by means of f-2f interferometry, and
setting a carrier-envelope offset frequency of the pulsed laser radiation in accordance with a third manipulated variable derived from the third controlled variable.
6. A device for generating stabilized, pulsed laser radiation, comprising:
a mode-locked laser that generates pulsed laser radiation at a repetition frequency, wherein the spectrum of the pulsed laser radiation is a frequency comb having a number of equidistant spectral lines,
a first high-frequency oscillator that generates a high-frequency reference signal,
a first phase or phase frequency detector that derives a first controlled variable from the pulsed laser radiation and the reference signal by means of phase comparison,
a continuous-wave laser that generates narrow-band continuous-wave laser radiation at a reference wavelength,
a first control element that derives a first manipulated variable from the first controlled variable and controls the continuous-wave laser for setting the reference wavelength in accordance with the first manipulated variable,
a superposition element that superposes the continuous-wave laser radiation and the pulsed laser radiation and derives a second controlled variable from the superposition signal, and
a second control element that derives a second manipulated variable from the second controlled variable and controls the mode-locked laser for setting the repetition frequency in accordance with the second manipulated variable.
7. The device according to claim 6 , wherein the continuous-wave laser comprises a frequency shifter that is controlled by the first control element for setting the reference wavelength.
8. The device according to claim 6 , wherein the first high-frequency oscillator is an oven-controlled crystal oscillator.
9. The device according to claim 6 , wherein the first high-frequency oscillator is GPS disciplined or is stabilized in another manner by means of locking to a frequency standard.
10. The device according to claim 6 , further comprising: an f-2f interferometer that derives a third controlled variable from the pulsed laser radiation, wherein a third control element is provided, which derives a third manipulated variable from the third controlled variable and controls the mode-locked laser for setting a carrier-envelope offset frequency.
11. The device according to claim 6 , further comprising: a second high-frequency-oscillator, the frequency of which can be adjusted, wherein the superposition element comprises a second phase or phase frequency detector which derives the second controlled variable from the signal of the second high-frequency-oscillator and the superposition signal by means of phase comparison.
12. The device according to claim 11 , wherein the second high-frequency oscillator is also GPS disciplined or stabilized in another manner by means of locking to a frequency standard.
13. The device according to claim 6 , wherein a regulating bandwidth of the first control element is in a frequency range below a cut-off frequency, and a regulating bandwidth of the second control element is in a frequency range above the cut-off frequency, wherein a phase noise of the first high-frequency oscillator below the cut-off frequency is less than a phase noise of the continuous-wave laser, and the phase noise of the continuous-wave laser above the cut-off frequency is less than the phase noise of the first high-frequency oscillator.
14. The method according to claim 1 , wherein a line width of the continuous-wave laser radiation is less than 1 kHz.
15. The method according to claim 1 , wherein a line width of the continuous-wave laser radiation is less than 100 Hz.