Research On The Typical Fractional-Dimensionality Superluminescent Diode And Relevant Fundamental Theoretical Problems

The essential ideas of the theory of fractional dimensionality electron-states architectures were proposed in 2012.As the new concept of energy level dispersion(or divergence)was introduced in it,the theory has changed the understanding of the electron-states architectures.The theory of fractional dimensionality electron-states architectures declares that any electronic energy level is not an ideal line with zero-linewidth in non-extreme case,but slightly and unexceptionally dispersive.This allows different energy levels to merge together and truly(not approximately)become a continuous band in semiconductor materials.Because of the fractional dimensionality theory of heterostructures,we can describe the electron-states architectures and its evolution in semiconductor heterostructures more accurately,especially more realistically,and it is possible to conceive and develop higher performance electronic and optoelectronic devices.The semiconductor superluminescent diode is a light source that has both the laser-like high power and the LED-like broad optical power spectrum to a certain extent.At present,it is widely used in the fields of fiber optic gyroscope,optical time domain reflectometer and optical coherence tomography.Among the various performance specifications of superluminescent diodes,the power-bandwidth product is the most basic and the most important one.The significance of the power bandwidth product improvement not only lies in the index itself,but also leaves room for the improvement of other related indicators.Replacing typical bulk material heterostructure with quantum well heterostructure has a advantage in improving the power and power efficiency of superluminescent diodes,but it does not perform well in the spectral bandwidth of superluminescent diodes.This is because the electron density-of-state(DOS)function of a typical quantum well heterostructure is stepped,and accordingly its carrier spectral density(including electron spectral densityin the conduction band and hole spectral density in the valence band)curve is zigzag,rather than a single peak structure in the typical bulk material heterostructure.If a typical fractional dimension heterostructure between "well" and "bulk" is adopted,it is possible to overcome thedeficiencies of the conventional quantum well superluminescent diodes mentioned above.This paper takes the fractional dimension theory as the starting point,and relies on the National Natural Science Foundation project "Theoretical and Experimental Research on Energy-Level Dispersion in the Electronic State of Crystals and Fractional Dimensional Effects"(Project Number:61674020)and related international cooperation projects of the Ministry of Science and Technology The combination of fractional dimension theory and superluminescent diodes and related basic theoretical issues,the main research results and innovations are as follows:1.A detailed study of the superluminescent diode gain-bandwidth comprehensive analysis model based on the fractional dimension electronic state system theory,focusing on the optimization of the thickness of the quantum well superluminescent diodes active region,designed for the comparison of device performance experiments The quantum well epitaxial wafer structure and related multiple waveguide structures have formulated the later process flow of device preparation and carried out device preparation experiments.2.Based on the above superluminescent diode analysis model,formulate the comparison rules of the performance of superluminescent diode devices under different conditions,test and analyze the rules of the power and spectral width of the device with the thickness and temperature of the active area of the quantum well.The validity of the theory of fractional dimension electronic state system and the feasibility of optimizing the performance of superluminescent diode based on this theory are verified.3.Through a series of numerical calculations,the basic theoretical issues related to the electronic system of fractional dimensions are further studied.The dispersion integer 2D and dispersion integer 3D electronic state density function curves based on the asymmetric linear dispersion function are given and established.The final form of the definition of the similarity function between the dispersive integer 2D and the integer 2D and the dispersive integer 3D object to be compared,the more accurate energy level dispersion width value for the specific situation of the GaAs material system is obtained and the changes of the intersection point of dimensional similarity function with Fermi level.