Laser physics simulation program

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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

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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

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Physical model
Population evolution DN2-N1
l2
E2
g
Interaction media EM wave
Relaxation, pumping
Population equilibrium
Deq(l2-l1)/g
Intensity evolution J
l1
E1
g
Cavity loss, abs
Laser Gain
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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

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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

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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

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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

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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

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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

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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

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Demonstration
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Threshold

• Threshold study
• Study of spontaneous emission
• Starting the laser with DsDeq
• Starting parameters pump0.5, Loss0.2
• Increase pump until threshold
• Laser starting with DsltDeq
• Starting parameters pump3, Loss0.2
• Observation of the oscillating behavior before
  steady state

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Power versus loss

• Threshold study
• Study of spontaneous emission
• Starting the laser with DsDeq
• Starting parameters pump0.5, Loss0.2
• Increase pump until threshold
• Laser starting with DsltDeq
• Starting parameters pump3, Loss0.2
• Observation of the oscillating behavior before
  steady state

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Homogenous Inhomogenous Laser

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

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Pump pulsed relaxation

• Oscillating relaxation
• Study of laser relaxation
• Starting the laser with inhomogenous media
• Starting parameters pump10, Loss0.5
• Pump duration 300 fs

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Pump pulsed QSwitch

• Study of Qswitch laser
• Starting the laser with homogenous media
• Starting parameters pump2.5, Loss0.5
• Pump duration 100 fs check uncheck Qswitch button

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CW Mode Locking

• Pulse duration study
• Long Pulse
• Starting parameters pump3.5, Loss0.1
• Increase N2 for shorter pulse, Dispersion 0

N210-10
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CW Mode Locking

• Dispersion effect
• Short Pulse
• Starting parameters pump3.5, Loss0.1
• N2 0.6, Dispersion between 29 and 39