Research On Mid-infared Transistor-injected Quantum Cascade Laser And Its Characteristics

The mid-infrared waveband possesses important research and application values.It not only covers two commonly used atmospheric windows of 3 ~ 5?m and 8 ~ 14?m,but also contains a large number of molecular absorption peaks.It is the working waveband of trace gas detection,medium and long-range atmospheric communication,environmental monitoring,military information countermeasures and many other applications.Due to the lack of materials with lasing wavelengths in MIR in nature,the research of MIR lasers poses great challenges.Quantum cascade laser(QCL)can work directly in MIR,having the advantages of small size,simple structure,long life,integration with integrated circuits,etc.,and has important research and application value.Tunable QCL can reduce system complexity and application cost,achieve a wider detection range and improve detection system performances.Researchers have achieved the tunability of QCL in a variety of methods,but often have the characteristics of high manufacturing difficulty,high use cost,and low reliability,which is difficult to apply on a large scale.Based on the traditional QCL,the transistor-injected quantum cascade laser(TI-QCL)studied in this thesis combines the structural characteristics of a bipolar junction transistor to improve it from a traditional double-contact QCL to a three-contact device.With two independent regulating voltages,the output power and lasing wavelength can be adjusted independently,which contribute to a better tunability.This thesis focuses on the device characteristics of TI-QCL,and studies a large number of algorithms for modeling and simulation of the device,including self-consistent Schrodinger-Poisson equation algorithm,numerov Schrodinger Equation solver with complex potential boundaries(NEGF),etc.,provides a lot of theoretical supports and research tools for device research.Based on the simulation algorithm,this thesis makes a thorough research on the tunability of TI-QCL,including the theoretical model of the device and the actual simulation results.By studying the distributions of energy levels and electrons,and the optical gain of the device as well,detailed analysis and discussion of the characteristics of TI-QCL have been proceeded,including the center wavelength,tuning range,sensitivity,etc.,achieved a center wavelength of 36.6% near 9.8 ?m.The tuning sensitility is about 5?m / V,and the temperature characteristics of the device are studied as well.Based on tunability,this thesis also studies the TI-QCL-based supercontinuum,including spectral broadening by changing the structural parameters of the superlattice period,which is common to the ordinary QCL,and modification of doping parameters in different periods to obtain periodic electric field strength to achieve spectral broadening,which is unique for TI-QCL.Under the combined effects of these two methods,this device achieves a spectral broadending range in MIR,and it has a relatively good flatness as well.Through the research in this thesis,it is confirmed that TI-QCL has better tunability and wide spectral characteristics than traditional QCL,and it also has good research values and development prospects.