Fiber  Laser  for  ERL  

Zach  Ulibarri  Mentor:  Zhi  Zhao  

Introduc:on  •  Goal:  – Mode  locked  laser  oscillator  – 50  MHz  repe::on  rate  

– Designed  for  emiEance  measurement  

Laser  Basics  •  Popula:on  inversion  in  gain  medium  

Laser  Basics  •  S:mulated  photon  emission  

Laser  Basics  •  Light  emits  and  repeats  process  

Mode  Locked  Lasers  •  Saturable  absorber  

Intensity  

Transmission  

Mode  Locked  Lasers  

•  With  saturable  absorber  in  place,  random  noise  can  create  pulses  

Mode  Locked  Lasers  

•  How  do  we  add  sufficient  noise  to  the  cavity?  

Mode  Locked  Lasers  

•  How  do  we  add  sufficient  noise  to  the  cavity?  

Ar:ficial  Saturable  Absorber  •  Wave  plates  create  phase  shiS  induced  intensity  modula:on  

Experimental  Setup  

Top  View  

Mode  Locked  Lasers  

19.8ns    

Mode  Locked  Lasers  •  Detector  is  too  slow  

FWHM  suggests  Pulse  width  =  1.22  ns  

Autocorrelator  Measurement  •  Michelson  interferometer  creates  small  delay  •  Aligned  pulses  create  second  harmonic  genera:on  

Intensity  Autocorrela:on  

Intensity  Autocorrela:on  

FWHM  suggests  pulse  width  =  8ps.  Very  large!  

Chirp  •  Index  of  refrac:on  depends  on  wavelength  

•  Compensate  with  diffrac:on  gra:ng  

Chirp  

Intensity  Autocorrela:on  

Dechirped  Autocorrela:on  

Dechirped  Autocorrela:on  

FWHM  =  330  fs  =  1.5*220  

Interferometric  Autocorrela:on  

FWHM  suggests  pulse  width  =  220fs  

Spectrum  

Simulated  Results  

200fs  

Agrees  with  es:mates  

Pulse  Energy  •  Peak  power  es:mated  from  pulse  energy  and  characteris:cs        Chirped                            Dechirped  

    "↓$%&'( = *↓+,- //            "↓$%&'( = *↓+,- //       

   

   

= 20301/50.5∗ 10↑6     = 53.301/50.5∗ 10↑6    

=1.0634  =4.0234  

Peak  Power  

*↓$(+5 = "↓$%&'( /6↓$%&'(      

= 1.06 ∗10↑−9 /200∗10↑−15      

=5.2851  

*↓$(+5 = "↓$%&'( /6↓$%&'(    

= 4.02 ∗10↑−9 /200∗10↑−15    

=20.151    

Chirped   Dechirped  

Ques:ons?