Efficient anti-Stokes generation through phase-matched four-wave mixing in higher-order modes of a microstructure fiber

Abstract

Phase-matched four-wave mixing in higher-order modes of microstructure fibers allows unprecedentedly high efficiencies of anti-Stokes frequency conversion to be achieved for subnanojoule femtosecond laser pulses. 70-fs pulses of 790-nm radiation were used to generate an anti-Stokes component at 520-530 nm in a higher-order mode of a microstructure fiber with a 4.8-microm core. The maximum ratio of the anti-Stokes signal energy to the energy of the pump component in the output spectrum is estimated as 1.7.

Mode-controlled spectral transformation of femtosecond laser pulses in microstructure fibers

“…The wavelength λ 0 of zero group-velocity dispersion for these modes lies close to the radiation wavelength of a Ti: sapphire laser (Fig. 7), which permits dispersion pulse spreading to be reduced and phase matching to be achieved for parametric four-wave mixing [20,21,27]. The mismatch of propagation constants δβ for the studied wave-mixing process as a function of the wavelength is shown in Fig.…”

“…Supercontinuum generation in MS fibers [9][10][11] is now intensely used in optical frequency metrology [12,13], ultrafast photonics [14], spectroscopy [15], and biomedical optics [16]. MS fibers offer much flexibility in phase-matching third-harmonic generation [17] and fourwave mixing [18], permitting not only broadband emission, but also isolated spectral components [19][20][21] to be generated with a high efficiency. Microstructure-fiber frequency converters substantially enhance the capabilities of low-energy femtosecond lasers in photochemistry [22] and nonlinear spectroscopy [15].…”

“…7). This situation is optimal for phase-matched four-wave mixing [21,28]. Efficient generation of a spectrally isolated anti-Stokes fre- (online color at www.interscience.wiley.com) Propagation constant β normalized to the wave number k = ω/c (ω is the frequency and c is the speed of light) as a function of dimensionless frequency ka (a is the diameter of holes in the fiber cladding) for the fundamental (blue curve) and higher order (red, green, navy, yellow, and pink) guided modes of the microstructure fiber shown in Fig.…”

Anomalous bending effect in photonic crystal fibers

“…Since the corresponding Stokes shift (210 cm −1 ) is much smaller than the Raman shift (440 cm −1 ), the stimulated process can be attributed to a phase-matched four-wave mixing (FWM) process. Efficient FWM generated in guided higher-order modes have been demonstrated in multimode microstructured silica fibers [7][8][9]. However, in such FWM the anti-Stokes and the Stokes pulses are generated in the same mode as the pump pulses so that no intermode energy conversion is encountered.…”

Time-Spectral Visualization of Fundamental Ultrafast Nonlinear-Optical Interactions in Photonic Fibers

“…In addition, phasematched inter-bandgap FWM generation may play a role in the observed behavior (Rasmussen et al, 2008). Previously, intermodally phase-matched FWM (Stolen & Leibolt, 1976;Akimov et al, 2003) as well as third harmonic generation (Efimov & Taylor., 2005b) were observed in both regular fibers and PCFs. Inter-bandgap phase-matched FWM is a very similar process and thus appears likely to contribute to the generation mechanism.…”