IEVref: 731-03-76 ID: Language: en Status: Standard Term: material dispersion parameter Synonym1: Synonym2: Synonym3: Symbol: М Definition: the quantity which characterizes the material dispersion defined as: $M\left(\lambda \right)=-\frac{1}{{c}_{0}}\frac{\text{d}N}{\text{d}\lambda }=\frac{\lambda {\text{d}}^{2}n}{{c}_{0}\text{d}{\lambda }^{2}}$ where n is the refractive index, N is the group index, λ is the wavelength in vacuum, and c0 is the speed of light in vacuum NOTE 1 – For many optical fibre materials, M is zero at a specific wavelength λ0, usually around 1300 nm. The sign convention is such that M is positive for wavelengths shorter than λ0 and negative for wavelengths longer than λ0. NOTE 2 – Pulse broadening caused by material dispersion in a unit length of optical fibre is give by M times spectral linewidth (Δλ), except at or near λ = λ0, where terms proportional to (Δλ)2 are important. Publication date: 1991-10 Source: Replaces: Internal notes: 2016-02-08: Editorial correction: c corrected to c0 in accordance with correspondence with VT 60050 convenor 2016-12-06. JGO 2016-03-07: Editorial changes: "velocity of light in vacuum" replaced by "speed of light in vacuum". See correspondence "Questions re part 731" 2015-02 and 2015-03. JGO 2017-06-02: Cleanup - Remove Attached Image 731-03-76.gif CO remarks: TC/SC remarks: VT remarks: Domain1: Domain2: Domain3: Domain4: Domain5: