3/15/2023 0 Comments Silica zero dispersio wavelengthThe research was carried out by the Dantus Research Group, developer of MIIPS technology for automated pulse compression. Note: In all silica-based optical fibers, minimum Material Dispersion occurs naturally at a wavelength of approximately 1.3 m. This finding could have significant applications in design of ultrafast lasers such as titanium sapphire lasers, or ytterbium fiber lasers where fused silica is the main propagation medium. Zero dispersion wavelength for fused silica lies near 1300nm and for light with shorter wavelength the material dispersion naturally occurs to be normal (positive). In a single-mode optical fiber, the zero-dispersion wavelength is the wavelength or wavelengths at which material dispersion and waveguide dispersion cancel one another. Taking advantage of their ability to control the spectral phase of the input laser pulses, and measuring the nonlinear intensity-dependent changes in the index of refraction, the researchers found that intense negatively chirped pulses acquired additional negative chirp, which is considered as anomalous. Given that nonlinear refractive index changes are expected to depend on pulse intensity, the researchers were surprised to find that laser-induced group velocity dispersion depends on the sign of the input chirp. When an intense laser pulse enters a dielectric medium, it perturbs the medium causing nonlinear changes of the index of refraction. Researchers at Michigan State University discovered that fused silica can exhibit anomalous dispersion at 800nm under certain conditions. The silica-glass fibers used in such systems are doped and exhibit zero dispersion close to 1.312 um. These findings have significant implications regarding self-compression and the design of femtosecond lasers. The presence of a zero-dispersion wavelength offers significant advantages in the design of optical fiber communications systems in which optical pulses carry information, as will become evident in Secs. Normal induced dispersion can be explained by the Kerr effect, but anomalous LI-GVD, found when the input pulses have negative pre-chirp, cannot. For a 5.5 × 10(11) W/cm(2) peak intensity, LI-GVD values are found to vary from -3 to + 15 times the material GVD. This opens up the possibility of realizing visible frequency combs for a range of different applications. Using a small diameter and small wall thickness, dispersion equalization within the visible is predicted. We present 20fs(2) accuracy laser-induced group velocity dispersion (LI-GVD) measurements, resulting from propagation of a femtosecond laser pulse in 1mm of fused silica, as a function of peak intensity. In particular, the zero dispersion wavelength is shown to be highly tunable by changing the thickness of the shell. In modern telecommunication systems, both λ min and λ ZMD and the respective dispersion coefficients are very important in the design of both low-loss and low-dispersion systems.Rasskazov G, Ryabtsev A, Pestov D, Nie B, Lozovoy VV, Dantus M. The fabricated micro-ring resonator with the optimized dimensions exhibits near-zero dispersion of 0.04 to 0.1 ps/m/nm over a wavelength range of 130 nm. For silica the minimum in attenuation occurs at 1.55 μm, and for ZBLAN at 2.45 μm. The zero dispersion wavelengths are always less than λ min, where the attenuation is least. 2 The zero dispersion wavelengths occur at 1.724 μm and 1.312 μm for ZBLAN and silica, respectively. 2.12 data is shown for the dispersion coefficient D λ for a typical fluoride glass (ZBLAN) and, for comparison, silica. This is the very important zero material dispersion wavelength (ZMD). At the wavelength where dn/dλ is a minimum, d 2n/dλ 2 is zero and the group velocity is a maximum. (2.19) and (2.21) that material dispersion affects pulse propagation though both the first derivative (group velocity) and the second derivative (dispersion coefficient).Īs mentioned above, dn/dλ has a minimum value at the point of inflection in the dispersion curve. (b) The spectral absorption of silica, and (inset) water. The units for the dispersion coefficient are practical units more relevant to the long lengths of fibers used in telecommunication applications. (a) The zero dispersion wavelength as a function of diameter for silica microspheres in air and water.
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