DFB laser driving power using hybrid digita-analog closed loop

As the driving current fluctuation can affect distributed feedback (DFB) laser's emitting wavelength and optical power, a high stable DFB lasers driver was designed and developed by using hybrid digita-analog closed loop method, which was based on TMS320LF28335 core controller. In terms of hardware design, the proposed laser driver utilized operational amplifier deep feedback theory to increase the stability of the whole system (better than 410-5). In software design, Ziegle-Nichols PID algorithm was introduced to eliminate the micro deviation between the real driving current and the theory current value (less than 0.5%). Meanwhile, the driver possessed surge protection circuit when power was on/off, time delay soft start circuit and over current protection circuit, et al. Using the aforementioned driver, a driving test was performed on a DFB laser with a center wavelength of 1 742 nm. Experiments show that the stability of driving current is better than 410-5 (RMS) during long term (220 h) stability performance test, which meets the requirement of DFB laser and has good practical significance.