Spectral Shift
Dynamic wavelength shift in semiconductor lasers occurs as a result of the change in refractive index in the active region during intensity modulation. It is possible to evaluate the shift in wavelength by determining the refractive index change of the active region as a result of carrier injection. A complete analysis of spectral shift during direct modulation found that the refractive index of the active region varies proportionally to carrier density and hence the wavelength varies proportionally to injected current.
Experimentally, a good fit for the shift in wavelength is given by:
where I0 is the injected current and Ith is the lasing threshold current.
Read more about this topic: Laser Diode Rate Equations
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