Coherent anti-Stokes Raman scattering in a hollow dielectric waveguide

Abstract

Hollow waveguides are shown to enhance coherent anti-Stokes Raman scattering by two to three orders of magnitude for low-pressure gases. Theoretical and experimental comparisons of signals generated by tight focusing in a cell with those generated in a hollow waveguide are preented. These arguments show that maximum conversion in the hollow waveguide occurs at pressures on the order of several atmospheres compared to greater than 50 atm for tight focusing, and for low pressures enhancements are on the order of the square ofthe waveguide length to confocal beam parameter ratio.

Enhanced spontaneous Raman scattering and gas composition analysis using a photonic crystal fiber

“…High-order, nongrazing modes have high loss and thus are of limited use for enhancement of nonlinear interactions. Most classic hollow-capillary, nonlinear optics enhancement experiments that have been reported describe output signals that required phase matching and consequently did not benefit from the collection of a large number of waveguide modes or the collection of a large solid-angular output [5][6][7][8][9]11,12]. Thus these experiments are not strongly affected by the requirement of grazing incidence.…”

“…It is noted that classical hollow capillary tubes have also been used for the enhancement of nonlinear optical interactions [5][6][7][8][9][10][11][12][13]. These capillaries work best with rays that propagate at grazing incidence, i.e., when only the fundamental EH 11 or low-order waveguide mode propagates [14][15][16][17][18].…”

Nonlinear Optics and Solitons in Photonic Crystal Fibres

“…The fibre also can be bent so that the entire device can be made compact. Using an enhancement factor λl/a 2 [92], where l is the constant intensity interaction length and a is the beam radius, it has been demonstrated that the low loss HC-PCFs can beat capillary guides by the factor ∼ 10 6 [13]. This remarkable efficiency boost is due to the fact that in hollow capillary waveguides l is limited by loss and scales as l ∼ a 3 /λ 2 [93], while in high quality PCFs l practically equals the fibre length.…”

Bragg resonance‐enhanced coherent anti‐Stokes Raman scattering in a planar photonic band‐gap waveguide

“…25,26 Similarly to gas-filled hollow fibers, the waveguide regime of non-linear optical interactions in our structure improves the efficiency of wave-mixing and harmonic-generation processes relative to the regime of tightly focused pump beams owing to a radical increase in the interaction length. On the other hand, a periodic perturbation of the refractive index introduced by the diffraction grating (see the inset in Fig.…”