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Laser physics simulation program

Laser physics simulation program. Lionel Canioni University Bordeaux I France. The Mode program. Goal: visualization of laser dynamics and operating types. Interacting program working on a tabletop computer Useful for Graduate and undergraduate student in lasers courses

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Laser physics simulation program

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  1. Laser physics simulation program Lionel Canioni University Bordeaux I France

  2. The Mode program • Goal: visualization of laser dynamics and operating types. • Interacting program working on a tabletop computer • Useful for Graduate and undergraduate student in lasers courses • Illustration of the different laser operations principle

  3. Principle of working • The program: • Solve the laser master equation in an infinite time loop • Display continuously the physical parameters of the laser • Calculation at each point of the cavity and for all time: number of photon by mode and the population difference versus frequency

  4. Physical model Population evolution: D=N2-N1 l2 E2 g Relaxation, pumping Interaction media EM wave Population equilibrium Deq=(l2-l1)/g Intensity evolution: J l1 E1 g Cavity loss, abs Laser Gain

  5. Simulations • Master equation are solve for each cavity mode with wave propagation equation • All the parameters let us study a large amount of laser type • Cw laser , threshold, pulsed laser, CW mode locked laser, QSwitch, mode beating etc…

  6. Laser Dialog Box • Cavity parameters • Length • Number of resonant optical frequency • Optical gain media • Frequency • Emission abs cross section • Spectral width • Spectroscopic model • Optical Pumping • CW or Pulsed pump • Loss • Pump Power • Display Control • Continuous or step by step display • Choose between several representation • Pulse propagation parameters • Non linear coefficient and dispersion

  7. Cavity parameters • Length in µm of the laser: • The cavity length match the gain media length • Small cavity for visual mode representation • Number of resonant optical frequency • One can choose between 1 (single mode laser) and 41 optical frequencies allowed in the cavity • FP filter equivalent

  8. Optical gain media • Frequency • Selection of the central frequency by the resonant frequency of the cavity. Change with cavity length change wavelength • Spectral width • Gain media width( arbitrary unit) • Emission abs cross section • Low gain or high gain laser • Spectroscopic model • Homogenous or Inhomogenous model example gas laser or Nd Yag laser

  9. Optical Pumping • Loss • Accumulated during laser propagation • CW or Pulsed pump • CW Pumping and flashed pump allowed Qswith simulation. Flash duration and repetition rate available • Pump Power • Control the efficiency between pump power and optical transfer

  10. Pulse propagation parameters • Effective parameters for fs propagation • Second order dispersion: useful for pulse stretched • Nonlinear coefficient: SPM mod locking : scattering of energy between modes

  11. Display Control Choose between several representation: • Frequency domain: mod representation, spectrum representation • Time domain: Difference population, output power, pulse inside the laser rod • Standard value: pulse width, power, intensity, wavelength Continuous or step by step display: • Multithread application allowed permanent tuning and adjustment while display

  12. Demonstration

  13. Threshold Threshold study: • Study of spontaneous emission Starting the laser with Ds=Deq Starting parameters: pump=0.5, Loss=0.2 Increase pump until threshold • Laser starting with Ds<Deq Starting parameters: pump=3, Loss=0.2 Observation of the oscillating behavior before steady state

  14. Power versus loss Threshold study: • Study of spontaneous emission Starting the laser with Ds=Deq Starting parameters: pump=0.5, Loss=0.2 Increase pump until threshold • Laser starting with Ds<Deq Starting parameters: pump=3, Loss=0.2 Observation of the oscillating behavior before steady state

  15. Homogenous Inhomogenous Laser Spectral study: • Study of inhomogenous laser Starting the laser with spectra and population window • Homogenous Laser Observation of the spectral narrowing

  16. Pump pulsed: relaxation Oscillating relaxation: • Study of laser relaxation Starting the laser with inhomogenous media Starting parameters: pump=10, Loss=0.5 Pump duration 300 fs

  17. Pump pulsed QSwitch • Study of Qswitch laser Starting the laser with homogenous media Starting parameters: pump=2.5, Loss=0.5 Pump duration 100 fs check uncheck Qswitch button

  18. CW Mode Locking Pulse duration study: • Long Pulse Starting parameters: pump=3.5, Loss=0.1 Increase N2 for shorter pulse, Dispersion =0 N2*10-10

  19. CW Mode Locking Dispersion effect: • Short Pulse Starting parameters: pump=3.5, Loss=0.1 N2 =0.6, Dispersion between 29 and 39

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