Anomalous spectral behaviour of diffracted chirped Gaussian pulses in the near field
Pan Liu-Zhana, Lü Bai-Dab
a Department of Physics, Luoyang Normal College, Luoyang 471022, China; Institute of Laser Physics & Chemistry, Sichuan University, Chengdu 610064, China; b Institute of Laser Physics & Chemistry, Sichuan University, Chengdu 610064, China; State Key Laboratory of Laser Technology, Huazhong University of Science & Technology, Wuhan 430074, China
Abstract By using the Fourier transform method, analytical expressions for the axial power spectrum and near-field intensity in the spacetime domain of chirped Gaussian pulses diffracted at an aperture are derived, which permit us to study changes in spectral and temporal profiles of the chirped Gaussian pulses both analytically and numerically. Detailed numerical results and physical analysis show that spectral anomalies take place in the neighbourhood of certain critical distances, and the shifting of maximum and splitting of temporal intensity profiles appear. In particular, for ultrashort chirped pulses, there exists also spectral switch. Besides the truncation parameter, the chirp parameter and pulse duration affect the behaviour of spectral switches.
Received: 21 July 2003
Revised: 24 September 2003
Published: 06 July 2005