Ultrabroadband Optical Pulses with Quadratic Spectral Phase Part I: Temporal Form
A time-domain representation for ultrabroadband optical pulses that includes chirp, stretching, and absolute phase is presented. This is accomplished by holomorphic Fourier transform of a class of spectra that include spectral phase up to second order, resulting in derivatives of the Faddeeva function $w(ζ)$. Relating the real part of this pulse to physical quantities, its shape is investigated. The derivative order $η$ is shown to dictate relative spectral bandwidth. The absolute phase determines the mixing of more localized (Gaussian decay) and less localized (algebraic decay) components of $w(ζ)$. Second order spectral phase accounts for linear dispersion and is shown to cause a sheering of the Wigner-Ville distribution of the pulse, akin to the linear chirp that would be seen in the quasi-monochromatic case. Along with $η$ it determines the pulse length and number of oscillations. A correspondence with the slowly varying envelope approximation is derived for large order $η$, although the algebraic decay persists.