Measurement of transient wavelength and line-width of DFB diode laser by delayed self-heterodyne interferometer

We measured the transient wavelength and line width of distributed feedback (DFB) diode laser by the short fiber delayed self-heterodyne (FDSH) interferometer. Experimental results have shown that the beat frequency signal and power spectrum were consistent with the theory. The beat frequency was measured from 20mA to 120mA injection current. The emission wavelength and linewidth dependence on injection current where the laser heat sink temperature, T, was held constant at temperature T=-5 degress Celsius, namely, tuning characteristics of transient were obtained. We compared the transient characteristics with the static one of the DFB diode laser. The results showed that the deviation was about 0.4nm. This meant that, in most cases the transient wavelength and line width of diode laser could not be substituted by the static one of the diode laser. This innovative feature was helpful to improve the accuracy of laser systems based on multi-gas sensing.