Pspice Model And Simulation Analysis Of Quantum Cascade Laser

Quantum cascade laser is a unipolar optical device based on intersubbandelectronic transitions in quantum well to emit light. Its wavelength is no more restrictedby semiconductor’s band gap width for the energy band engineering to cut quantumwell, which greatly expands the range of light wave. That makes quantum cascade laserbecome one of the main light source in the far infrared optical communication field. Themultistage cascade structure of quantum cascade laser makes its lasing efficiencygreatly improved. Compared to traditional subband compound semiconductor laser,quantum cascade laser has incomparable superiority! The far infrared spectralcharacteristics can be used for toxic gas and chemical detection, narrow linewidthmakes them very attractive in the field of coherent optical communication, considerabledirect intensity modulation bandwidth makes them very attractive on intensitymodulation optical communication system. Many applications reflect an extremelyimportant scientific value and commercial value to research and design quantumcascade laser.In this paper, based on the basic structure and the energy level model of thequantum cascade laser, rate equations are derived and pspice equivalent circuit model ofquantum cascade laser is established through equivalently and intuitively transforming.A quantum cascade laser net list generator is developed to encapsulate the model toimprove applicability and reliability of the quantum cascade laser. The basic features ofquantum cascade laser subcircuit model are simulated, including DC analysis, transientanalysis and frequency analysis. From the point of the software simulation, quantumcascade laser theory and characteristics are analyzed as follows to verify the correctnessand reliability of the model:The DC P-I characteristics of quantum cascade lasers is simulated and analyzed.The difference of the external differential quantum efficiency between quantum cascadelaser and conventional semiconductor laser is compared. The impact of photon lifetime,cascading number, resonant cavity length and spontaneous emission coefficient on theDC P-I characteristic features of quantum cascade laser is discussed. The transient characteristics of quantum cascade laser is simulated and analyzed.The damping shock was not seen in the transient response, but there is turned-on delaytime and rise time in the transient response. The causes of the delay time of the quantumcascade laser are analyzed and discussed. Also the impact of pulse peak current andspontaneous emission coefficient on the quantum cascade laser delay time is analyzedand discussed.The frequency characteristics of the quantum cascade laser is simulated anddiscussed. The influence of the bias current on the frequency characteristics and themodel constants on the direct modulation response3dB bandwidth of the quantumcascade laser are analyzed and discussed.