Supercontinua for high-resolution absorption multiplex infrared spectroscopy

Abstract

Supercontinua generated in highly nonlinear fibers by ultrashort-pulse lasers can be used for high-resolution Fourier transform absorption spectroscopy. The practical advantages of these bright ultrabroadband light sources for spectroscopy in the near-infrared region are reported. A Cr(4+):YAG femtosecond laser broadened by an extruded soft-glass photonic crystal fiber, emitting from 1200 to 2200 nm and from 675 to 950 nm, provides a spectral radiance 1 x 10(5) times higher than that of a 3000 K blackbody and 10(2) times higher than that of synchrotron radiation. The C(2)H(2) and NH(3) overtone spectra are recorded by using this source within a few seconds.

Generation of infrared supercontinuum radiation: spatial mode dispersion and higher-order mode propagation in ZBLAN step-index fibers

“…Numerous applications have emerged since the first supercontinuum in bulk glass was reported by Alfano et al [2], in such diverse fields as spectroscopy [3,4] and optical metrology [5,6]. Recently, supercontinua have been pushed into the mid-infrared, making room for new applications in spectroscopy and microspectroscopy [7][8][9][10], as the molecular fingerprint region can be reached.…”

Computationally-efficient FDTD modeling of supercontinuum generation in photonic crystal fibers

“…Supercontinuum (SC) generation in photonic crystal fibers (PCFs) has become one of promising ways to produce cost-effective broadband infrared radiation sources applicable in broadly-understood spectroscopy (Hult et al 2007;Mandon et al 2008). The process of SC generation relies on appropriate balance between dispersion and various third-order nonlinear effects, such as self-phase modulation, soliton generation/fission, and four-wave mixing (Agrawal 2007).…”

IR microscopy utilizing intense supercontinuum light source

“…Recently, the supercontinuum technique was extended to the infrared spectral range beyond 2.6 μm by applying soft glass fibers such af ZBLAN [10,11]. This provides many possibilities for applications in molecular spectroscopy [12]. SC generation is based upon nonlinear interaction between a short laser pulse and the fiber material in a process where the spectral width of the laser pulse widens from a few nanometers to several optical octaves [13][14][15].…”

“…SC generation is based upon nonlinear interaction between a short laser pulse and the fiber material in a process where the spectral width of the laser pulse widens from a few nanometers to several optical octaves [13][14][15]. The spectral brightness of the infrared SC is several orders of magnitude higher than that from a thermal infrared source and comparable to the brightness of synchrotron sources [2,12,16]. Since the SC is generated in a single spatial mode in the fiber, the light has a high degree of spatial coherence and is able to be focused to a diffraction limited spot size in principle.…”