femtosecond pulses 1 Longitudinal modes: Recapitulation D las = - - PowerPoint PPT Presentation

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femtosecond pulses 1 Longitudinal modes: Recapitulation D las = - - PowerPoint PPT Presentation

Aug 03, 2023 315 likes •561 views

Kerr Lens Modelocking for femtosecond pulses 1 Longitudinal modes: Recapitulation D las = Spectral width of each mode Quality factor, Q T 0 = Time interval between two successive maxima = Time for decay of amplitude to A 0 / e T 0 <<

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SLIDE 1

1

Kerr Lens Modelocking for femtosecond pulses

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SLIDE 2

Longitudinal modes: Recapitulation

Dlas = Spectral width of each mode

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SLIDE 3

Quality factor, Q

T0 = Time interval between two successive maxima  = Time for decay of amplitude to A0/e T0 <<  Dlas = Spectral width of each mode

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SLIDE 4

Longitudinal modes in a bunch

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I = A*A

Ipeak = N2E0

2

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SLIDE 6

Intensity = Modulus squared electric field

Modelocking

Ipeak = N2E0

2

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SLIDE 7

Repetition rate

Intensity = Modulus squared electric field First maximum: Second maximum: Difference in time T = t2–t1:

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SLIDE 8

Pulse duration

Intensity = Modulus squared electric field

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SLIDE 9

Pulse duration and Intensity

  • M. Didomenico, J. App. Phys. Lett. 35, (1964) 2870; Hargrove et al. Appl. Phys. Lett. 5 (1964) 4
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SLIDE 10

Transform limited pulses

Time domain Frequency domain Gaussian Gaussian

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SLIDE 11

Transform limited pulses

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SLIDE 12

Transverse modes

  • E. W. Small, Chapter 2, Topics in Fluorescence Spectroscopy, J. R. Lakowicz
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SLIDE 13

Transverse modes

  • E. W. Small, Chapter 2, Topics in Fluorescence Spectroscopy, J. R. Lakowicz

Intensity

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SLIDE 14

Kerr Effect

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SLIDE 15

Kerr Effect

Intensity-dependent refractive index

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SLIDE 16

Kerr Effect

Intensity-dependent refractive index

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SLIDE 17

Kerr Effect

Intensity-dependent refractive index Kerr lensing

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Kerr Effect

Intensity-dependent refractive index Kerr lensing Intense beam: Focused Weak beam: Not focused

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Kerr Effect

Intensity-dependent refractive index Kerr lensing Intense beam: Focused Weak beam: Not focused Pulsed light

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SLIDE 20

Kerr Effect

Intensity-dependent refractive index Kerr lensing Intense beam: Focused Weak beam: Not focused Pulsed light CW light

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SLIDE 21

Kerr Effect

Intensity-dependent refractive index Kerr lensing Intense beam: Focused Weak beam: Not focused Pulsed light CW light

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SLIDE 22

Kerr Lens Modelocking

Intensity-dependent refractive index Kerr lensing Intense beam: Focused Weak beam: Not focused Pulsed light CW light

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SLIDE 23

Chirping

Kerr lensing Intense beam: Focused Weak beam: Not focused Pulsed light CW light Courtesy:

  • J. A. Mondal, BARC