Laser Device for Generating an Optical Frequency Comb

Abstract

The invention relates to a laser device comprising a laser source (1), which is configured to emit pulsed laser radiation (2) with a spectrum in the form of a frequency comb having a plurality of equidistant spectral lines, an optical modulator (3), which is configured to shift the frequency of the laser radiation (2), and a control unit (10), which is configured to control the modulator (3) by means of a control signal (6). It is the object of the present invention to demonstrate an improved way, compared to the prior art, of generating an optical frequency comb that is stabilized in terms of the CEO frequency, in which the CE phase is also adjustable. To this end, the invention proposes that the laser radiation (2) emitted by the laser source (1) is stabilized in terms of the carrier-envelope frequency. Furthermore, the invention relates to a method of generating an optical frequency comb.

1 . A laser device comprising:
 a laser source, which is configured to emit pulsed laser radiation with a spectrum in the form of a frequency comb having a plurality of equidistant spectral lines,   an optical modulator, which is configured to shift at least one of the phase of the laser radiation and the frequency of the laser radiation, and   a control unit, which is configured to control the optical modulator by means of a control signal,   
       wherein the laser radiation emitted by the laser source is stabilized in terms of the carrier-envelope frequency. 
     
     
         2 . The laser device according to  claim 1 , wherein the laser radiation emitted by the laser source is also stabilized in terms of the pulse repetition frequency. 
     
     
         3 . The device according to  claim 1 , wherein the optical modulator is an acousto-optic modulator, wherein the control signal excites an acoustic wave in the medium of the acousto-optic modulator. 
     
     
         4 . The device according to  claim 3 , wherein the control unit is configured to generate the control signal as a radio-frequency signal at the pulse repetition frequency of the laser radiation or an integer multiple thereof. 
     
     
         5 . The device according to  claim 3 , wherein the control unit is configured to generate the control signal as a radio-frequency signal at a frequency shifted by a predefinable frequency offset relative to the pulse repetition frequency of the laser radiation or an integer multiple thereof. 
     
     
         6 . The device according to  claim 4 , wherein the control unit is further configured to set the phase of the control signal. 
     
     
         7 . The device according to  claim 6 , wherein the control unit is further configured to vary the phase setting of the control signal from laser pulse to laser pulse. 
     
     
         8 . The device according to  claim 1 , wherein the carrier-envelope frequency of the laser radiation emitted by the laser source equals zero. 
     
     
         9 . The device according to  claim 1 , wherein the laser source comprises:
 a mode-locked oscillator,   two separate radiation paths for the laser radiation emitted by the mode-locked oscillator, wherein the optical modulator is located in one of the two radiation paths, and   a difference-frequency generator, in which the laser radiation supplied via the two radiation paths is superposed.   
     
     
         10 . A method of generating an optical frequency comb, comprising the steps of:
 generating pulsed laser radiation with a spectrum in the form of a frequency comb having a plurality of equidistant spectral lines, and   shifting the phase and/or frequency of the laser radiation according to a control signal,   wherein the generated laser radiation is stabilized in terms of the carrier-envelope frequency.   
     
     
         11 . The method according to  claim 10 , wherein the frequency of the laser radiation is shifted by means of an optical modulator, in particular an acousto-optic modulator. 
     
     
         12 . The method according to  claim 10 , wherein the frequency of the laser radiation is shifted by the pulse repetition frequency or an integer multiple thereof. 
     
     
         13 . The method according to  claim 10 , wherein the frequency of the laser radiation is shifted by a frequency that differs from the pulse repetition frequency or an integer multiple thereof by a frequency offset. 
     
     
         14 . The method according to  claim 10 , wherein the carrier-envelope phase of the laser radiation is adjusted by phase setting of the control signal. 
     
     
         15 . The method according to  claim 14 , wherein the phase setting of the control signal is varied from laser pulse to laser pulse.