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Complex representation of the electric field Pulse description --- a propagating pulse A Bandwidth limited pulseNo Fourier Transform involved Actually,

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Presentation on theme: "Complex representation of the electric field Pulse description --- a propagating pulse A Bandwidth limited pulseNo Fourier Transform involved Actually,"— Presentation transcript:

1 Complex representation of the electric field Pulse description --- a propagating pulse A Bandwidth limited pulseNo 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

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4 Chirped pulse

5 z t z = ct z = v g t A propagating pulse

6 t A Bandwidth limited pulse

7 Actually, we may need the Fourier transforms (review) 0

8 Properties of Fourier transforms Shift Derivative Linear superposition Specific functions: Square pulse Gaussian Single sided exponential Real E(  E*(-  Linear phase Product Convolution Derivative

9 Construct the Fourier transform of Pulse Energy, Parceval theorem Poynting theorem Pulse energy Parceval theorem Intensity ? Spectral intensity

10 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

11 Frequency and phase - CEP Instantaneous frequency In general one chooses: And we are left with 02 -2 4 4 Time (in optical periods) 1 0 Field (Field) 7 02 -2 4 4 Time (in optical periods) 1 0 Field (Field) 7

12 Slowly Varying Envelope Approximation Meaning in Fourier space??????

13 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)

14 Pulse duration, Spectral width Two-D representation of the field: Wigner function

15 Gaussian Chirped Gaussian Wigner Distribution

16 Wigner function: What is the point? Uncertainty relation: Equality only holds for a Gaussian pulse (beam) shape free of any phase modulation, which implies that the Wigner distribution for a Gaussian shape occupies the smallest area in the time/frequency plane. Only holds for the pulse widths defined as the mean square deviation


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