Spectral coherence properties of temporally modulated stationary light sources

Abstract

It is shown that partially spectrally coherent pulses of light with controlled spectral coherence properties can be generated by temporal modulation of beams emitted by stationary light sources. A method for generation of spectrally Gaussian Schell-model-type pulses is presented.

Temporal self-splitting of optical pulses

“…One could start with a stationary, spatially coherent light source (a superluminescent diode, for instance), and use electro-optic modulation to produce a train of Gaussian Schell-model pulses with a low degree of spectral and temporal coherence [33]. Then the spectral modulation technique proposed in Ref.…”

“…In addition to spatial domain effects, optical pulses with partial spectral or temporal coherence have recently attracted researchers' widespread attention, for their possible applications in optical telecommunication, imaging, and fiber optics [29][30][31][32][33][34][35][36][37][38][39][40][41]. Temporally partially coherent pulse trains are generated by many real sources, such as free-electron and excimer lasers, supercontinuum in microstructured fibers, or random lasers [42], although practical schemes for controlling or modulating the temporal (or spectral) coherence are scarce [43].…”

Propagation of spatial coherence in fast pulses

“…In works on nonstationary fields [6,7,20], the emphasis has been on sources that are spatially fully coherent and of infinite extent. Such sources produce polychromatic plane waves.…”

“…When the assumption of stationarity does not hold, the correlation functions that describe the field become two-time or two-frequency correlation functions, and the Wiener-Khintchine-Einstein theorem no longer holds. For these reasons and others, the timeaveraged measurements made with an interferometer or a spectrometer have a more complicated relationship with the nonstationary sources that generated them [6][7][8] than in the stationary case. Some sort of prior knowledge is necessary to make unambiguous estimates of the statistical properties of the sources based on the measured data.…”

“…Generalized spectra and cross-spectral densities for a number of classes of nonstationary fields have been defined and investigated [6,20,21]. In many of the experiments described above, the field is made up of a large number of stochastic pulses with a periodic probability density function exhibiting a fixed temporal period.…”