16
Complex representation of the electric field ulse description --- a propagating pulse A Bandwidth limited pulse No Fourier Transform involved tually, we may need the Fourier transforms (review) Construct the Fourier transform of Pulse Energy, Parceval theorem Frequency and phase - CEP Slowly Varying Envelope Approximation Pulse duration, Spectral width

Complex representation of the electric field

  • Upload
    devin

  • View
    26

  • Download
    3

Embed Size (px)

DESCRIPTION

Complex representation of the electric field. Pulse description --- a propagating pulse. A Bandwidth limited pulse. No Fourier Transform involved. Actually, we may need the Fourier transforms (review). Construct the Fourier transform of. Pulse Energy, Parceval theorem. - PowerPoint PPT Presentation

Citation preview

Page 1: Complex representation of the electric field

Complex representation of the electric field

Pulse description --- a propagating pulse

A Bandwidth limited pulse No Fourier Transform involved

Actually, we may need the Fourier transforms (review)

Construct the Fourier transform of

Pulse Energy, Parceval theorem

Frequency and phase - CEP

Slowly Varying Envelope Approximation

Pulse duration, Spectral width

Page 2: Complex representation of the electric field
Page 3: Complex representation of the electric field

-6 -4 -2 0 2 4 6

-1

0

1

-20 -10 0 10 20

Delay (fs)

Page 4: Complex representation of the electric field

Chirped pulse

Page 5: Complex representation of the electric field

z

t

z = ctz = vgt

A propagating pulse

Page 6: Complex representation of the electric field

t

A Bandwidth limited pulse

Page 7: Complex representation of the electric field

Actually, we may need the Fourier transforms (review)

0

Page 8: Complex representation of the electric field

Properties of Fourier transforms

Shift

Derivative

Linear superposition

Specific functions: Square pulse Gaussian Single sided exponential

Real E(E*(-

Linear phase

Product Convolution

Derivative

Page 9: Complex representation of the electric field

Construct the Fourier transform of

Pulse Energy, Parceval theorem

Poynting theorem

Pulse energy

Parceval theorem

Intensity?

Spectral intensity

Page 10: Complex representation of the electric field

Description of an optical pulse

Real electric field:

Fourier transform:

Positive and negative frequencies: redundant information Eliminate

Relation with the real physical measurable field:

Instantaneous frequency

Page 11: Complex representation of the electric field

Frequency and phase - CEP

Instantaneous frequency

In general one chooses:

And we are left with

0 2-2 44

Time (in optical periods)

-1

1

0

-1

Field (Field)7

0 2-2 44

Time (in optical periods)

1

0

-1

Field(Field)7

Page 12: Complex representation of the electric field

Slowly Varying Envelope Approximation

Meaning in Fourier space??????

Page 13: Complex representation of the electric field

Robin K Bullough Mathematical Physicist

Robin K. Bullough (21 November 1929-30 August 2008) was a British Mathematical Physicist famous for his role in the development of the theory of the optical soliton.

J.C.Eilbeck J.D.Gibbon, P.J.Caudrey and R.~K.~Bullough, « Solitons in nonlinear optics I: A more accurate description of the 2 pi pulse in self-induced transparency »,Journal of Physics A: Mathematical, Nuclear and General,6: 1337--1345, (1973)

Page 14: Complex representation of the electric field

Pulse duration, Spectral width

Two-D representation of the field: Wigner function

Page 15: Complex representation of the electric field

-2 -1 0 1 2

-2

-1

0

1

2

-2 -1 0 1 2

-2

-1

0

1

2

Time TimeF

requ

ency

Fre

quen

cy

-2 -1 0 1 2

-2

-1

0

1

2

-2 -1 0 1 2

-2

-1

0

1

2

Time TimeF

requ

ency

Fre

quen

cyGaussian Chirped Gaussian

Wigner Distribution

Page 16: Complex representation of the electric field

Wigner function: What is the point?

Uncertainty relation:

Equality only holds for a Gaussian pulse (beam) shape free of anyphase modulation, which implies that the Wigner distribution for aGaussian shape occupies the smallest area in the time/frequencyplane.

Only holds for the pulse widths defined as the mean square deviation