Analysis of chirp characteristics of DFB lasers and integrated laser-modulators

Abstract

A new method of analyzing the chirp characteristics of directly modulated lasers and integrated laser-modulators is presented in this paper. Phase-circuit has been introduced into the circuit model of distributed feedback (DFB) lasers in the analysis. Therefore, the chirp characteristics of the device can be obtained by simulating the modified circuit model. The simulation results agree well with the published data. Furthermore, this modified model is combined with the circuit model of electroabsorption (EA) modulators to simulate the chirp characteristics of the monolithic integration of a DFB laser and an EA modulator. The simulation is focused on the dependence of the frequency chirp of the integrated device on the isolation resistance between laser and modulator. Much lower chirp can be seen in the integrated lightwave source compared to the directly modulated laser.

Optimizing Equivalent Circuit Model Parameters of DFB Lasers With RSM Model and NSGA-II Algorithm

“…Sample points are important initial parameters in the RSM calculation, and the reasonable selection of sample points can effectively improve the accuracy of the RSM model. In order to solve the multi-parameter co-optimization of the laser, the constraint bounds of the optimized parameters are determined according to the existing literature as follows: Г [0.10, 0.70], g0 [1.0×10 -12 m 3 /s, 8.0×10 -12 m 3 /s], ε [1.0×10 -24 m 3 , 30×10 -24 m 3 ], Rl [0.10, 0.70] and Rr [0.10, 0.70], which are extracted from actual DFB lasers [40][41][42][43]. Response value is another important initial parameter in the construction of the response surface model, where the reliability of the model is determined by the accuracy of the response value.…”