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npe
- 1. Fiber laser mode-lockedby nonlinear polarization rotation
- 2. Work purpose • Discoverbasic properties of fiber laser mode- locke based on NPE; • Find necessary conditions to mode-lock laser by NPE.
- 3. NPE based onphenomena of: 𝑛 𝑧 = 𝑛2 𝑃𝑥 𝑧 + 𝑃𝑦 𝑧 nonlinear refractive index 𝑃𝑥,𝑦 - power of x,y polarization. In due of this some cross effects arise between polarizations and lead to its dynamics Cross effect absent for linear or circular polarization
- 4. Polarization state oflight can be shown like a poit in this plane
- 5. Laser scheme normal dispersion HWPQWPQWP 1 2 34 coupler output 5 pump Y - polarization
- 6. The pulse polarizationdynamics in the points of cavity. Marker on a curve shows point in a pulse with highest power.
- 7. How the schemeworks ? • QWP 1 makes from X polarised pulse a some polarization state shown as a point 1 in the previous slide; • Its state developes as pulse goes in the cavity 1-2- 3; • The duty of plates pair 3-4 is to move a polarization state from case of 3 to 4 with pulse highest part in the X polarization. So trougth the cavity pass only part of pulse with highest power. • That’s how that leads the laser to pulsing.
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- 10. Autocorrelation and compressedpulse at point (5)
- 11. Laser scheme normal+anomal dispertion HWPQWPQWP 1 2 34 coupler output 5 pump Y - поляризация
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- 15. Autocorrelation and compressedpulse at point (5)
- 16. Conclusions • The NPEmode-locked laser exploite a phenomena of pulse polarization dynamics in a cavity; • The use of waveplates allowed us to choose a right pulse treatment to enchance pulsing.