OPTIMIZED PHYSICAL PARAMETER SET FOR A 1550-NM DFB LASER SOURCE WITH ENHANCED MODULATION CHARACTERISTICS, REDUCED SOURCE LINEWIDTH AND CHIRPING, AND SUPPRESSED HARMONIC AND INTER-MODULATION DISTORTION FOR CATV FREQUENCY BAND OF OPERATION

摘要

The laser parameter set extracted show that the Proposed DFB optimum laser rate equation parameter set (designated as Laser-4) exhibits favorably highest mode confinement factor and the least linewidth enhancement factor which facilitates in the narrowing of the linewidth , reduced chirping and reduced RIN. Table-2 indicates that Y and Z parameters are the highest and Avg RIN and fres values are the least in Proposed DFB optimum laser rate equation parameter set (Laser-4) even though its linewidth is larger than that of Laser-2 and Laser-3. The comparison of the respective L-I curves, RIN spectrum displays, small-signal and large-signal characterization of these lasers clearly shows that, out of all these lasers investigated in this work. Proposed DFB optimum laser rate equation parameter set (Laser-4) is characterized by the best values of the parameter set and with best possible results of RIN spectrum, small-signal and large-signal characterization. Next, the HD and IMD correcting ability of these lasers were investigated in CD-RD IM-DD SCM models at laser quantum efficiency equal to 0.4, laser active layer volume equal to 1.5 E-10 cm , carrier lifetime equal to 1 ns and photon lifetime equal to 3 ps. Least compensation is achieved by Laser-1 while Laser-2 and Laser-3 are mildly compensated. The compensated DFB optimum laser rate equation parameter set (Laser-4) exhibits the most favorable design and operational parameters out of the extracted samples with lowest threshold current, highest clipping tolerant current range, smallest carrier density at transparency, highest mode confinement factor, smallest linewidth enhancement factor, best IMD and HD suppression and lowest RIN peak power.