Tunable pulse width laser

Abstract

A method of tuning the time duration of laser output pulses, the method including spectrally dispersing optical pulses and further comprising providing an optical pulse having a time duration and a spectral bandwidth; spectrally dispersing ( 243, 245 ) the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse; outputting ( 226 ) an optical output pulse having a first time duration that is responsive to the selected change in time duration; providing another optical pulse; changing the amount of spectral bandwidth of the another optical pulse ( 272 ) to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change; and outputting ( 226 ) another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse.

The invention claimed is: 
     
       1. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse;   wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing the amount of spectral bandwidth;   wherein changing the amount of spectral bandwidth comprises changing optical power; and   wherein changing the optical power comprises amplifying.   
     
     
       2. The method of  claim 1  wherein the optical output pulse and the another optical output pulse have time durations that are longer, respectively, than the optical pulse and the another optical pulse. 
     
     
       3. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   
       outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse;
 wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing the amount of spectral bandwidth; 
 wherein changing the amount of spectral bandwidth comprises changing optical power; and 
 wherein changing the optical power comprises attenuating. 
 
     
     
       4. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   
       outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse;
 wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing the amount of spectral bandwidth; 
 wherein changing the amount of spectral bandwidth comprises changing optical power; 
 wherein the method further comprises providing a pulsed laser source; and 
 wherein changing the optical power comprises changing the output power of the pulsed laser source. 
 
     
     
       5. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   
       outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse;
 wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing the amount of spectral bandwidth; 
 wherein changing the amount of spectral bandwidth comprises changing an amount of self phase modulation; and 
 wherein changing an amount of self phase modulation comprises providing an amplifier and changing the gain of the amplifier. 
 
     
     
       6. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse; and   providing a laser source comprising a passively mode locked fiber laser comprising a laser cavity including a SESAM mode locking element and a length of rare earth doped optical fiber having normal dispersion at the output wavelength of the fiber laser cavity, the passively mode locked fiber laser providing pulses having a time duration of no less than 1 ps and no greater than 100 ps and a spectral bandwidth of no greater than 2 nm.   
     
     
       7. The method of  claim 5  comprising providing a laser source comprising a passively mode locked fiber laser comprising a laser cavity including a SESAM mode locking element and a length of rare earth doped optical fiber, and wherein providing an amplifier and changing the gain of the amplifier comprises providing a non linear fiber amplifier downstream of the laser source and changing the gain thereof to change an amount of self-phase modulation provided by the nonlinear amplifier. 
     
     
       8. The method of  claim 1  wherein changing the amount of spectral bandwidth comprises broadening the spectral bandwidth. 
     
     
       9. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse; and   wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing the amount of spectral dispersion.   
     
     
       10. The method of  claim 9  wherein changing the amount of spectral dispersion comprises:
 providing first and second spectrally dispersive optical elements that provide different amounts of spectral dispersion; and 
 changing from spectrally dispersing optical pulses with the first spectrally dispersive element to spectrally dispersing optical pulses with the second spectrally dispersive optical element. 
 
     
     
       11. The method of  claim 9  wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing both of the amount of spectral bandwidth and the amount of spectral dispersion. 
     
     
       12. The method of  claim 11  comprising providing at least one criteria related to a pulse characteristic and determining to change both the amount of spectral dispersion and the spectral bandwidth responsive to a determination regarding the at least one criteria. 
     
     
       13. The method of  claim 12  wherein the pulse characteristic comprises the desired temporal pulse width of the second pulse. 
     
     
       14. The method of  claim 12  wherein the pulse characteristic comprises pulse distortion. 
     
     
       15. The method of  claim 9  wherein changing the amount of spectral bandwidth or changing the amount of spectral dispersion comprises changing both the amount of spectral bandwidth and the amount of spectral dispersion so as to provide substantially continuous tuning of the temporal pulse width of optical output pulses of the laser system over a selected range of temporal pulse widths and so as to limit the amount of distortion of optical output pulses having temporal pulse widths within the selected range. 
     
     
       16. The method of  claim 1  wherein optical output pulses provided by the laser system have a temporal time duration of no less than 1 ps and no greater than 1 ns. 
     
     
       17. A method of tuning the time duration of output pulses output from a laser system, wherein the method comprises spectrally dispersing optical pulses and further comprises:
 providing an optical pulse having a time duration and a spectral bandwidth;   spectrally dispersing the optical pulse so as to provide a selected change in the time duration of the pulse responsive to the spectral bandwidth of the pulse;   outputting an optical output pulse from the laser system having a first time duration that is responsive to the selected change in time duration;   providing another optical pulse;   changing the amount of spectral bandwidth of the another optical pulse to be different than that of the optical pulse or changing the amount of spectral dispersion so that spectrally dispersing the another optical pulse provides a change in time duration that is different than the selected change;   
       outputting another optical output pulse having a second time duration that is responsive to the different change in time duration, the second time duration of the another optical output pulse being different than the first time duration of the optical output pulse; and
 refraining from outputting compressed optical output pulses wherein the time duration of the optical output pulses would be less than 50% of their time duration prior to compression. 
 
     
     
       18. The method of  claim 5  wherein optical output pulses provided by the laser system have a temporal time duration of no less than 1 ps and no greater than 1 ns. 
     
     
       19. The method of  claim 9  wherein optical output pulses provided by the laser system have a temporal time duration of no less than 1 ps and no greater than 1 ns. 
     
     
       20. The method of  claim 17  wherein optical output pulses provided by the laser system have a temporal time duration of no less than 1 ps and no greater than 1 ns. 
     
     
       21. A laser system configured for providing output pulses, comprising:
 a pulsed laser source for providing seed pulses with a time duration;   a nonlinear optical waveguide downstream of the pulsed laser source for providing spectral bandwidth modification of pulses; and   a spectrally dispersive optical element downstream of the nonlinear optical waveguide, wherein the spectrally dispersive optical element comprises a grating and wherein the grating increases the time duration of received pulses responsive to both the amount of spectral bandwidth modification provided by the nonlinear optical waveguide and the amount of spectral dispersion provided by the grating so as to provide output pulses of the laser system which have a time duration that is responsive to said increase in time duration and that is longer than the time duration of the associated seed pulse.   
     
     
       22. The laser system of  claim 21 , wherein the nonlinear optical waveguide provides spectral bandwidth modification via self phase modulation. 
     
     
       23. The laser system of  claim 21 , wherein the system is configured such that one or both of the amount of spectral bandwidth modification or the spectral dispersion of the grating can be selectively changed so as to selectively change the time duration of the pulses downstream of the grating, thereby providing a tunable pulse width laser system, wherein the system is configured to selectively change a peak power of the pulses so as to selectively change the amount of spectral bandwidth modification. 
     
     
       24. The laser system of  claim 21 , wherein the non-linear optical waveguide comprises an optical amplifier comprising the non-linear optical waveguide, and wherein the laser system comprises a controller comprising a processing unit, an interface and a memory, said memory containing instructions executable by said processing unit whereby the controller is operative to vary the gain of the amplifier responsive to user instructions received via the interface, thereby controlling a peak power of the pulses thereby controlling an amount of self phase modulation and the amount of spectral bandwidth modification so as to allow the time duration of output pulses from the laser system to be varied. 
     
     
       25. The laser system of  claim 24 , wherein said optical amplifier comprises an optical fiber amplifier. 
     
     
       26. The laser system of  claim 21 , wherein the grating comprises a fiber Bragg grating. 
     
     
       27. The laser system of  claim 26 , wherein the fiber Bragg grating comprises a chirped fiber Bragg grating. 
     
     
       28. The laser system of  claim 21 , wherein the system is configured such that a peak power of the pulses can be selectively changed so as to selectively change the amount of spectral bandwidth modification so as to selectively change the time duration of the pulses downstream of the grating, thereby providing a tunable pulse width laser system. 
     
     
       29. The laser system of  claim 28 , wherein the amount of spectral bandwidth modification is selectively changed by selectively changing an amount of self-phase modulation provided by the nonlinear optical wavequide by selectively changing the peak power of the pulses. 
     
     
       30. The laser system of  claim 29 , wherein the non-linear optical waveguide comprises a length of passive optical waveguide. 
     
     
       31. The laser system of  claim 30 , comprising a variable optical attenuator for changing the peak power of the pulses so as to change the self phase modulation introduced by the passive optical waveguide and hence the amount of spectral bandwidth modification, thereby allowing the time duration of output pulses from the laser system to be varied. 
     
     
       32. The laser system of  claim 21 , wherein the grating comprises a tunable grating such that the amount of spectral dispersion can be selectively changed so as to selectively change the time duration of the pulses downstream of the tunable grating, thereby providing a tunable pulse width laser system. 
     
     
       33. The laser system of  claim 21 , wherein the system is configured such that both of the amount of spectral bandwidth modification and the spectral dispersion of the grating can be selectively changed so as to selectively change the time duration of the pulses downstream of the spectrally dispersive optical element, thereby providing a tunable pulse width laser system, wherein the system is configured to selectively change a peak power of the pulses so as to selectively change the amount of spectral bandwidth modification. 
     
     
       34. The laser system of  claim 21 , wherein optical output pulses provided by the laser system have a temporal time duration of no less than 1 ps and no greater than 1 ns.