LED Spectral Calculator

LED emission wavelength is set by the semiconductor band gap through λ ≈ 1240 / E_g (nm, eV), with the active material system determining which wavelengths are accessible — InGaN for 365–530 nm, AlGaInP for 530–650 nm, and InGaAs for the near-infrared. This calculator covers three spectral design problems. Wavelength from Band Gap converts an entered band gap energy to peak wavelength, photon energy, frequency, spectral region, and suggested material system. Spectral Width estimates the theoretical FWHM using the 1.8 k_BT thermal broadening approximation, reporting the result in THz, nm, and meV as a function of junction temperature. Pump Overlap computes the fraction of LED power falling within a narrowband absorption feature — useful for assessing LED pumping of rare-earth-doped fibers or laser gain media where spatial overlap with a narrow absorption line determines efficiency.