Modal analysis of photon-number statics in a supercontinuum laser pulse

A supercontinuum (SC) laser pulse, which is generated through third-order nonlinear process, is valuable light for various applications such as optical coherence tomography (OCT), and spectral measurement. Coherence of a SC pulse is one of the most important properties because the accuracy and sensitivity of these measurements are determined by its noise property. Recently, the second-order coherence property has been revealed by some numerical simulations and experiments [1, 2]. According to these previous reports, the coherence of the SC pulse has been almost lost through the spectral broadening process. However, the depletion of the coherence has been studied only in two bases: time and frequency. Thus, we experimentally study the coherent basis from noisy modes of the SC pulse by utilizing multimode quantum theory [3, 4].