Basic principles of ultrafast lasers

Components of the ultrafast laser system

 

Concepts of Mode Locking

in the Mode locking is a method to obtain in the ultrafast pulses from lasers, which are then
called mode-locked in the lasers mode
 in the  LOCKED phases for all the laser modes

  Basic principles of ultrafast lasers

Bandwidth vs Pulsewidth
see in diagram

 

Mode-locking Mechanisms

Active mode-locking

  •   Acousto-optic in the modulator
  •   synchronous in the pump mode-locking

Passive mode-locking

  •  in the saturable absorber in the (dye, solid-state)
  • optical Kerr in the effect

Types of Laser Output

 

Kerr-Lensing

  1.  in the Kerr medium (n = n0 + n2I)
  2. Low-intensity beam
  3. High-intensity in the ultrashort pulse
  4.  in the Focused pulse

 

Optical Kerr Effect

Intensity in the dependent refractive index: n = n0 + n2I(x,t).
 
Spatial (self-focusing)

  • provides in the loss modulation with suitable in the placement of gain in the medium (and a hard aperture).

Temporal (self-phase modulation)

  •  in the provides a pulse shortening mechanism with group in the velocity dispersion

Optical Kerr Effect

Refractive in the index in the depends on light intensity: n (I)= n + n2 I.
self-phase in the modulation due to temporal in the intensity in the variation
in the self-focusing due to transversal in the mode profile

Group Velocity Dispersion in the (GVD)

Optical in the pulse in a transparent medium in the stretches because of GVD

  • v = c / n – in the speed of light in
    a medium
  • n –depends on in the wavelength,
    dn/dl < 0 – normal dispersion.
  • High-intensity modes have smaller cross-sections and are less lossy. Thus, Kerr-lens is similar to saturating absorber!
  • Some in the lasing in the materials (e.g. Ti: in the Sapphire) can act as in the Kerr-media.
  • Kerr’s in the effect is much in the faster than saturating in the absorber in the allowing one to generate in the very short in the pulses (~5 fs).

GVD Compensation.

GVD can be in the compensated if optical in the pathlength is different for “blue” and “red”
components of the pulse.see in diagram
Components of the ultrafast laser system
 

Concepts of Mode Locking

in the Mode locking is a method to obtain in the ultrafast pulses from lasers, which are then
called mode-locked in the lasers modesee in diagram
 in the  LOCKED phases for all the laser modes

  Basic principles of ultrafast lasers

Bandwidth vs Pulsewidth
see in diagram

Mode-locking Mechanisms

Active mode-locking

  •   Acousto-optic in the modulator
  •   synchronous in the pump mode-locking

Passive mode-locking

  •  in the saturable absorber in the (dye, solid-state)
  • optical Kerr in the effect

Types of Laser Output


 

Kerr-Lensing

  1.  in the Kerr medium (n = n0 + n2I)
  2. Low-intensity beam
  3. High-intensity in the ultrashort pulse
  4.  in the Focused pulse

 

Optical Kerr Effect

Intensity in the dependent refractive index: n = n0 + n2I(x,t).
 
Spatial (self-focusing)

  • provides in the loss modulation with suitable in the placement of gain in the medium (and a hard aperture).

Temporal (self-phase modulation)

  •  in the provides a pulse shortening mechanism with group in the velocity dispersion

Optical Kerr Effect

Refractive in the index in the depends on light intensity: n (I)= n + n2 I.
self-phase in the modulation due to temporal in the intensity in the variation
in the self-focusing due to transversal in the mode profile

Group Velocity Dispersion in the (GVD)

Optical in the pulse in a transparent medium in the stretches because of GVD

  • v = c / n – in the speed of light in
    a medium
  • n –depends on in the wavelength,
    dn/dl < 0 – normal dispersion.
  • High-intensity modes have smaller cross-sections and are less lossy. Thus, Kerr-lens is similar to saturating absorber!
  • Some in the lasing in the materials (e.g. Ti: in the Sapphire) can act as in the Kerr-media.
  • Kerr’s in the effect is much in the faster than saturating in the absorber in the allowing one to generate in the very short in the pulses (~5 fs).

GVD Compensation.

GVD can be in the compensated if optical in the pathlength is different for “blue” and “red”
components of the pulse.

Red” in the component of the pulse in the propagates in the glass where group in the velocity is smaller than for the “blue” in the component

Components of an Ultrafast in the Laser

Pulse shortening in the mechanism.

  • Self-phase in the modulation and group velocity in the dispersion.
  •  in the Dispersion Compensation.
  •  in the Starting Mechanism.

Regenerative initiation

  • Cavity in the perturbation
  • Saturable Absorber (SESAM)

Cavity in the configuration of Ti:Sapphire laser

Tuning range 800-1200 nm
Pulse duration < 30 fs
Pulse energy < 20 nJ
Repetition rate 80 – 1400 MHz
Pump in the power: 4-15 W
Typical applications:

  • time-resolved in the emission

studies

  • multi-photon in the absorption

spectroscopy

  •  in the imaging

Amplification of fs Pulses

Concept:

  •  in the Stretch femtosecond in the oscillator in the pulse by 102 to 106 times
  •  in the Amplify
  •  in the Recompress amplified pulse

Chirped pulse amplification

  • Femtosecond in the pulses can be in the amplified to petawatt in the powers
  • Pulses so in the intense that in the electrons in the stripped in the rapidly from atoms

Red” in the component of a pulse is of the  propagates in the glass where is the group in the velocity is smaller  for the “blue” of a component.

Components of an Ultrafast in the Laser

Pulse shortening in the mechanism.

  • Self-phase in the modulation and group velocity in the dispersion see a diagram.
  •  in the Dispersion Compensation. see a diagram
  •  in the Starting Mechanism.

Regenerative initiation

  • Cavity in the perturbation
  • Saturable Absorber (SESAM)

Cavity in the configuration of Ti:Sapphire laser

Tuning range 800-1200 nm see a diagram.
Pulse duration < 30 fs
Pulse energy < 20 nJ

Repetition rate 80 – 1400 MHz
Pump in the power: 4-15 W
Typical applications:

  • time-resolved in the emission studies see a diagram
  • multi-photon in the absorption  spectroscopy see a diagram
  •  in the imaging

Amplification of fs Pulses


Concept:

  •  in the Stretch femtosecond in the oscillator see a diagram  in the pulse by 102 to 106 times
  •   Amplify see by a diagram.
  •  in the Recompress amplified pulse

Chirped pulse amplification

see a diagram

  • Femtosecond in the pulses can be in the amplified to petawatt in the powers see a diagram.
  • Pulses so in the intense that in the electrons in the stripped in the rapidly from a atoms.

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