Two-photon absorption effects on Raman gain in single mode As_2Se_3 chalcogenide glass fiber

Abstract

We report approximately 22 dB of Raman gain in single mode As(2)Se(3) chalcogenide glass fiber using 15 ps optical pump pulses from 1470 nm to 1560 nm. We employ a novel technique of cross-phase modulation induced sideband amplification to map out the Raman gain spectrum of this glass, and investigate the role of both degenerate and non-degenerate (ND) two-photon absorption (TPA). We find that for materials such as As(2)Se(3) where the Raman gain coefficient (gR) and TPA are comparable, it is critical to know and account for the role of both of these in order to achieve appreciable Raman gain. This is highlighted by our results, where we achieve significantly higher Raman gain at the longest pump wavelength (1560 nm), despite the fact that the Raman gain coefficient itself (gR) is smallest at this wavelength. This occurs because the TPA is significantly larger for shorter wavelengths in As(2)Se(3). We conclude, therefore, that for Raman gain applications in As(2)Se(3), L-band operation is strongly favored over C-band operation.

Stimulated Raman scattering in soft glass fluoride fibers

“…A variety of techniques has been used to study the Raman gain. This includes pump-probe techniques [12][13][14][15], studying the buildup of the Stokes beam for varying pump pulse length [16], and utilizing the amplification of sidebands through cross-phase modulation (XPM) [17]. Most of these techniques have been used to study either the gain in long fibers or in soft glass fibers with a high value of the Raman gain.…”

Zero-velocity solitons in high-index photonic crystal fibers

“…Transformations between the z and β representations are done by fast Fourier transforms. The nonlinear refractive index of As 2 Se 3 was recently measured to vary between 0:75 × 10 −5 μm 2 =W and 1:1 × 10 −5 μm 2 =W at wavelengths from 1470 to 1560 nm [21]. Here, an estimate of 6 × 10 −6 μm 2 =W is assumed for the longer wavelength of 2 μm.…”

“…For the Raman response function, Eq. (31), the peak Raman gain has been estimated to lie around a frequency shift of 7 THz with a spectral width of ∼1:4 THz [21]. To match these values, time constants of τ 1 ¼ 23 fs, τ 2 ¼ 230 fs were chosen, while f R was set to 0.2, similar to what one has for silica.…”

Bend loss in multimode chalcogenide fiber at infrared wavelengths

“…6 Chalcogenide fibers can withstand high-peak mid-infared laser power [7][8][9] with over 1 GW∕cm 2 (for nanosecond pulses) incident on the front face. 10 To date, significant efforts have been dedicated to this fiber system with research spanning methods to improve coupling through reduction in reflection loss 11 and modal matching, 12 impact of nonlinear absorption and optical scattering, 13 as well as design of complex singlecomponent microstructured fibers.…”