Pulsed laser source with adjustable grating compressor

Abstract

Various embodiments described herein relate to a laser source for producing a pulsed laser beam comprising a plurality of ultrashort optical pulses having a variable repetition rate. In one embodiment, the laser source comprises a fiber oscillator, which outputs optical pulses and a pulse stretcher disposed to receive the optical pulses. The optical pulses have an optical pulse width. The pulse stretcher has dispersion that increases the optical pulse width yielding stretched optical pulses. The laser source further comprises a fiber amplifier disposed to receive the stretched optical pulses. The fiber optical amplifier has gain so as to amplify the stretched optical pulses. The laser source includes an automatically adjustable grating compressor having dispersion that reduces the optical pulse width. The grating compressor automatically adjusts this dispersion for different repetition rates.

1 . A method of fabricating a waveguide in a medium, said method comprising: 
 producing an ultrafast pulsed laser beam comprising optical pulses having a pulse width between about 300 and 700 femtoseconds in duration and a wavelength in the range between about 490 and 550 nanometers;    directing at least a portion of said ultrafast pulsed laser beam into a region of said medium; and    removing said ultrafast pulsed laser beam from said region of said medium;    wherein said ultrafast pulsed laser beam directed into said region has sufficient intensity to alter the index of refraction of said medium in said region after said ultrafast pulsed laser beam is removed to form said waveguide in said medium.    
   
   
       2 . The method of  claim 1 , wherein said ultrafast pulsed laser beam has a laser fluence on said region of said medium of between about 5 J/cm 2  and 50 J/cm 2 .  
   
   
       3 . The method of  claim 1 , wherein said optical pulses have a repetition rate between about 100 kHz to 5 MHz.  
   
   
       4 . The method of  claim 1 , further comprising producing infrared light and frequency doubling said infrared light to produce said visible light beam.  
   
   
       5 . The method of  claim 1 , wherein said medium is selected from the group of materials consisting of substantially transparent crystal, glass, and polymer.  
   
   
       6 . The method of  claim 5 , wherein said medium comprises fused silica.  
   
   
       7 . The method of  claim 1 , wherein said medium comprises a material having a material ionization bandgap kg and said wavelength is between 3.0λ g  and 5λ g .  
   
   
       8 . The method of  claim 1 , further comprising translating said medium to form elongated waveguides.  
   
   
       9 . The method of  claim 1 , further comprising moving said ultrafast pulsed laser beam to form elongated waveguides.  
   
   
       10 . A system for fabricating a waveguide in a medium, said system comprising: 
 an infrared fiber laser outputting an ultrafast pulsed infrared laser beam;    a frequency doubler that receives said ultrafast pulsed infrared laser beam and outputs an ultrafast pulsed visible laser beam having a wavelength in a range between about 490 and 550 nanometers, said ultrafast pulsed visible laser beam comprising optical pulses having a pulse width of between about pulse width between about 300 and 700 femtoseconds in duration, said ultrafast pulsed visible laser beam illuminating a spatial region of said medium; and    a translation system for altering said spatial region to form said waveguide in said medium.    
   
   
       11 . The system of  claim 10 , wherein said infrared fiber laser comprises a Yb-doped fiber laser.  
   
   
       12 . The system of  claim 10 , wherein said infrared fiber laser outputs a wavelength between 1030 and 1050 nanometers, and said frequency doubler comprises a nonlinear optical element that produces light with a wavelength between 515 and 525 nanometers through second harmonic generation.  
   
   
       13 . The system of  claim 10 , wherein said ultrafast pulsed visible laser beam has a laser fluence on the spatial region of between about 5 J/cm 2  and 50 J/cm 2 .  
   
   
       14 . The system of  claim 10 , wherein said optical pulses have a variable repetition rate from about 100 kHz to 5 MHz.  
   
   
       15 . The system of  claim 10 , further comprising optics disposed to receive said ultrafast visible pulsed laser beam and illuminate said spatial region therewith.  
   
   
       16 . The system of  claim 15 , wherein said optics comprises a microscope objective.  
   
   
       17 . The system of  claim 15 , wherein said optics has a numerical aperture of less than about  1 . 0 .  
   
   
       18 . The system of  claim 10 , wherein said translation system comprises a translation stage on which said medium is disposed.  
   
   
       19 . The system of  claim 10 , wherein said translation system comprises a movable mirror.  
   
   
       20 . A system for fabricating a waveguide, said system comprising: 
 an ultrafast pulsed laser light source producing an ultrafast pulsed visible laser beam comprising optical pulses having a pulse duration between about 300 to about 800 femtoseconds and a wavelength between about 490 and 550 nanometers; and    a medium positioned in said beam, said medium having a physical structure and an index of refraction that depends on said structure, said structure being altered by said beam of visible light to thereby alter said index of refraction.    
   
   
       21 . The system of  claim 20 , wherein said medium has a material ionization bandgap λ g , and said wavelength is between 3.0λ g  and 5λ g .  
   
   
       22 . The system of  claim 20 , wherein said medium is selected from the group of materials consisting of substantially transparent crystal, glass, and polymer.  
   
   
       23 . The system of  claim 22 , wherein said medium comprises fused silica.