Stimulated Four-photon Mixing Research Articles

Influence of Temperature on Stimulated Raman Scattering in Single-Mode Silica Fibre

One piece of single-mode silica fibre is used to study of temperature characteristics of stimulated Raman scattering (SRS), additional peaks (double-humped) are observed at both sides of pump light and 1st-order Stokes light in the experiment. The frequency shift of the double-humped is calculated by stimulated Four–Photon mixing (SFPM) phase matching theory, the result is consistent with the frequency shift of this experiment. Simultaneously, the experimental conditions accord with the theoretical calculation of effective coherence length. We indicate that the double-humped phenomenon is caused by SFPM. The intensity of double-humped is first increased, then decreased and finally disappeared as the temperature increases. This phenomenon has been explained theoretically.

Mutual Interactions of Stimulated Raman Scattering and Stimulated Four-Photon Mixing in an Er3+-Doped Fiber

The mutual interactions of stimulated Raman scattering (SRS) and stimulated four-photon mixing (SFPM) in an Er3+-doped optical fiber have been studied with a tunable pulsed dye laser. Besides normal SRS and SFPM signals, we have observed some new spectral lines. Some of the new lines are attributed to three photon mixing (one from the pump, one from the first-order Stokes and one from SFPM) while the others are assigned to new SRS produced by one of the SFPM signals. The mechanisms of the generation of these new spectral lines are discussed.

Stimulated four-photon mixing and efficient polychromatic visible light generation in SiO2−based single-mode optical fibers pumped at 1.319 μm

Abstract The generation of near-infrared and intense visible light through stimulated multi-wave mixing processes in single-mode silica-based optical fibers pumped by a Q-switched and mode-locked Nd:YAG laser operated at 1.319 μm is described. The experimental results show that intense infrared light around 1.2 μm is produced via selp-hase-matched four-photon mixing at the minimum group velocity dispersion region of pure SiO2−core and P2O5−doped silica fibers. In the visible spectral region, from 580 nm to 600 nm, 20 W peak power 100-ps pulses were generated by pumping single spans of single-mode P2O5−doped and undoped SiO2−core fibers with 1.319-μm laser pulses. The signal light generated in such fibers propagated in the LP02 fiber mode and exhibited a threshold power that depended upon the fiber length and a critical length that was power dependent. Also, it exhibited an asymmetrical spectrum of a few nanometers bandwidth, with a long tail toward high frequencies. For GeO2−doped silica-based fibers, a m...

Enhancement of Anti-Stokes Line of Stimulated Four-Photon Mixing in an Er3+ Doped Silica Fiber

By using a pulsed dye Laser of nanosecond level as a pump source, we have investigated stimulated Raman scattering and stimulated four-photon mixing in Er3+ doped silica fibers. The experimental results show that all lines, including the pump radiation line, are obviously broadened and the anti-Stokes lines of stimulated four-photon mixing are greatly enhanced, and that the enhancement effect is in dependent of the wavelength.

Stimulated four-photon mixing in long birefringence single-mode fibers

Stimulated four-photon mixing in birefringent fibers with the pump wave propagating in two orthogonally polarized modes has been investigated. This process is interesting because of its long “coherence” length and low threshold power. The measured Stokes frequency shift was 60 cm -1.

Stimulated four-photon mixing with crossed pump dividing in an optical fiber

An experimental study of stimulated four-photon mixing with crossed pump dividing in a birefringent optical fiber is described. The interactive four photons are all in the same mode but with different polarizations. The pump wave is distributed in two orthogonal linear polarizations, and the polarizations of Stokes and anti-Stokes waves are also orthogonal. It is shown that the Stokes shift of this stimulated four-photon mixing process is related not only to the material dispersion but also to the waveguide dispersion and is directly proportional to the birefringence.

Stimulated four-photon mixing in bent few-mode optical fibres

A divided-pump four-photon mixing process is used to investigate the behaviour of modes on a bent few-mode optical fibre. The second-order mode set becomes non-degenerate, even for slight bending; the two modes propagate along the fibre with different group delays and preferred axes of symmetry. Our experimental results are compared with a theoretical analysis.

Intensity effects on the stimulated four photon spectra generated by picosecond pulses in optical fibers

The intensity dependence of stimulated four photon mixing (SFPM) spectra generated in 15 m of a 4-mode optical fiber by 25- ps pulses has been investigated. Despite the shortness of pulses, the SFPM conversion was highly efficient due to the intrinsic phase matching condition. In addition to usual features of SFPM spectra generated by nanosecond pump pulses, picosecond SFPM spectra were broadened by self phase modulation (SPM) and cross phase modulation (XPM). At the highest pump powers, intensity saturated frequency continua, arising from the combined effects of SFPM, stimulated Raman scattering (SRS), SPM, and XPM were generated all over the visible spectrum.

Continuously tunable multiple-order stimulated four-photon mixing in a multimode silica fiber

Stimulated four-photon mixing (SFPM) has been observed up to four orders in a 300-m-long, low-loss, large-core multimode silica fiber pumped by a dual-frequency dye laser. The phase-matching condition for SFPM was uncritically achieved in the multimode fiber, so that, by varying the frequency separation of the two laser lines, it was possible to tune continuously an intense line generated by SFPM under the Raman-gain curve in the range of 350 to 495 cm(-1).

Stimulated four-photon mixing in glass fiber waveguides in the spectral range 0.4–1.8 μ

The Stokes—anti-Stokes components were generated in few-mode fiber waveguides pumped by a neodymium garnet laser (λp = 0.532 and 1.064 μ). Such generation was attributed to stimulated four-photon processes. Phase matching in the waveguides was achieved by compensation of the material dispersion with the intermode dispersion. The emission frequency could be varied by varying the diameter of the waveguide core. When the pump wavelength was λp = 1.064 μ, the generation of light in the Stokes region was observed at wavelengths λ right up to 1.8 μ, whereas in the anti-Stokes region this occurred right up to 0.4 μ.

Phase-matched-stimulated four-photon mixing in silica-fiber waveguides

Stimulated four-photon mixing has been observed in silica-fiber waveguides. Phase matching is achieved by using the dispersion of the waveguide modes to compensate for bulk dispersion. The coherence lengths can be greater than 10 m and the gains more than double the usual Raman gain.