Why is Group Index used?
The Group Index is used, e.g., to calculate time delays for ultrashort pulses propagating in a medium, or the free spectral range of a resonator containing a dispersive medium. For crystals or glasses, the group index in the visible or near-infrared spectral range is typically larger than the ordinary refractive index, which determines the phase velocity. This implies that the group velocity is often (but not always) lower than the phase velocity.
How to Calculate Group Refractive Index at Standard Conditions?
Group Refractive Index at Standard Conditions calculator uses Group Refractive Index for Standard Condition = 1+(287.604+(4.8864/Wavelength^2)+(0.068/Wavelength^4))*10^-6 to calculate the Group Refractive Index for Standard Condition, The Group Refractive Index at Standard Conditions formula is defined as the ratio of the vacuum velocity of light to the group velocity in a medium. For calculating this, one obviously needs to know the refractive index at the wavelength of interest and its frequency dependence. Group Refractive Index for Standard Condition is denoted by n0 symbol.
How to calculate Group Refractive Index at Standard Conditions using this online calculator? To use this online calculator for Group Refractive Index at Standard Conditions, enter Wavelength (λ) and hit the calculate button. Here is how the Group Refractive Index at Standard Conditions calculation can be explained with given input values -> 1.000288 = 1+(287.604+(4.8864/20^2)+(0.068/20^4))*10^-6.