Time-bandwidth Product | previous | next | feedback |
(Acronym: TBP)
Definition: product of temporal and spectral width of a pulse
The time-bandwidth product of a pulse is the product of its temporal duration and spectral width (in frequency space). In ultrafast laser physics, it is common to specify the full width at half maximum (FWHM) both in time and frequency domain. The minimum possible time-bandwidth product is obtained for bandwidth-limited pulses. For example, it is ∼0.315 for bandwidth-limited sech2-shaped pulses or ∼0.44 for Gaussian-shaped pulses. This means e.g. that for a given spectral width, there is a lower limit for the pulse duration. This limitation is essentially a property of the Fourier transform.
The time-bandwidth product is often used for indicating how close a pulse is to the transform limit, i.e., how close the pulse duration is to the limit which is set by its spectral width. This is an aspect of "pulse quality"; bandwidth-limited pulses have the minimum possible time-bandwidth product, whereas chirped pulses have larger values. Many mode-locked lasers can generate nearly bandwidth-limited pulses, particularly when they are based on soliton mode locking.
See also: bandwidth-limited pulses, transform limit, Spotlight article 2007-10-11
