The Study Of High Speed And High Power Light-emitting Diode For Optical Communication

The arrival of the information era promotes the rapid development of local area network technology.The demand for a short distance,high-speed,large-capacity information transmission becomes more and more obvious.As the core components of the optical fiber communication system,light source devices must face some new challenges.We demand it can meet the needs of optical communications for high optical power and high modulation speed,but also has low cost and high reliability.The light source of LED has the advantages of low cost of devices and applications,and is particularly suitable for plastic optical fiber systems.Therefore,in the short distance optical fiber communication system,the LED has broad application prospects.However,the modulation speed of traditional LED is restrict to its recombination lifetime,which results in the modulation speed is only about 25MHz.it is difficult to meet the needs of light in optical communication.By combining the light-emitting diodes and transistors,a new type of heterojunction light emitting transistor(HBLET)was reported by M.Feng,which from University of Illinois at Urbana-Champaign.This structure will increase the modulation speed to GHz level.However,the optical power of the reported LET is very low,only microwatt level,it is also difficult to meet the requirements of light in optical communication.This article is based on the LED transient response of optical power,by analyzing the factors that influence the rising and falling edges of the optical power,discussed methods of improving LED modulation speed and studied by simulation.The work is based on Crosslight company's advanced semiconductor simulation software APSYS.The thesis includes the following four parts:(1)Combined with LED simulation,I studied that the modulation speed of LED is limited by radiative recombination lifetime.Simulate LED with a heterostructure and quantum well structure,study the impact of the quantum well and heterostructure to the modulation speed and optical power.(2)Plus a drain on the basis of the pn junction of LEDs to form a transistor-type LED,verify HBT structure can increase the modulation speed.Then I analyzed the relationship between amplification coefficient and optical power and modulation speed,and by changing the active region thickness,doping concentration and the interface barrier height of HBT structure,studied how the modulation speed and the optical power is affected by these parameters.(3)Combined with the above simulation results,simulate the LET structure,select material system of algainp to achieve emission wavelength in the plastic optical fiber communication window.Optimize the parameters to make the output light meet the requirements of modulation speed,optical power and contrast for short distance optical communication.(4)Propose a novel high-speed modulation LED structure,analyze of the principles of the new structure to achieve high-speed modulation theoretically.Study the structure by simulating using the software of APSYS.The results showed that the modulation speed and contrast have been improved significantly.