Study On Silicon Based Nitride Homologous Optoelectronic Integrated Chip For Visible Light Communication

With the rapid development of lighting technology and wireless communication technology,visible light communication will be the mainstream of next generation optical communication.However,the limitation of optical communication devices is an important problem that restricts its development.At present,the commonly used optical communication devices in the market are LED and visible light detectors,which are incapable of commendably apply to high speed visible light communication systems.The design of white LED on the market is intended to be illuminated rather than communication,and its very limited modulation bandwidth seriously affects the capacity improvement of the visible light communication system.The widely used visible light detector is Si-based detector,which is sensitive to the infrared band,and can not match perfectly with the luminescent band of the carrying signal,which is seriously affected by the background noise.In addition,the integration level of the visible light communication system is low due to the mutual independence of driving circuit,light source and detector.Optical integration technology has gained more and more attention in the fields of optical interconnection and optical communication with its advantages of small size,low energy consumption and large bandwidth.The new micro devices and integrated systems will lead the diversification of the information industry,which is an inevitable choice to cope with the post Moore era.The research of high speed optoelectronic devices should focus on the key science and technology,such as the compatibility of manufacturing process,the match of the mode field,the cross coupling of light mode.In this paper,the high response,low power,and high performance InGaN/GaN MQW LED will be studied as well as the optical detection function of InGaN/GaN MQW.Based on the optical properties of GaN materials,the photonic integration of silicon based GaN film is explored.Firstly,the multifunctional InGaN/GaN MQW diode is explored.Through the double processing technology,film thickness controllable suspended diode with a bottom silver reflector was successfully obtained on GaN-on-silicon wafer.Compared with common LED on silicon,the current density increases from 383.08 mA/mm² to 641.03 mA/mm² under same voltage bias;and the electroluminescence intensity is increased by 330%under equivalent current injection conditions.The real-time data transmission experiments demonstrate a practical use for the suspended device as both transmitter and receiver in a visible light communication system.Secondly,based on the dual functions of InGaN/GaN MQW diode device in LED and detector,a monolithic InGaN photonic circuit of a transmitter,waveguide,and receiver on a GaN-on-silicon platform is fabricated and characterized.Both the transmitter and the receiver,sharing identical InGaN/GaN multiple-quantum-well structures and fabrication procedures,work to emit light and detect light independently.Two kinds of waveguide structures are proposed.One is a directional coupler.The difference in etch rate caused by different exposure windows leads to an etching depth discrepancy using the one-step etching technique,which forms the InGaN directional coupler with the overlapped underlying slab.The dominant high-order mode coupling mechanism of the waveguide is verified via the beam propagation mothed,and the on-chip InGaN photonic integration experimentally demonstrates an in-plane light communication with a data transmission of 50 Mbps.The original model for realizing the 1×2N communication channel and the 2N x 1road photon calculation is provided.Another is the straight waveguide,of which fundamental mode is completely confined in active layer,can realize high quality and low loss optical transmission.By adopting SiO₂ isolation technology,the size of the active region was effectively reduced.Multi-dimensional light transmissions are experimentally demonstrated at 200 Mb/s.Finally,the detecting performance of InGaN/GaN MQW diode under turn-on state is explored;and achieves an in-plane full duplex VLC system based on monolithic GaN photonic integrated circuit.Two indentical suspended InGaN/GaN MQW diodes are connected via waveguide and a ring resonator.The ring resonator can be used as a light modulator to control the coupling and transmission of light which is an ideal optical device for a complex GaN based photonic circuit.Based on the finite difference time domain algorithm,the optical transmission characteristics of the ring resonator are analyzed,and the suspended photonic integration of LED,waveguide,ring resonator and photodiode on a single chip is fabricated and characterized,in which the photonic circuit is suspended by support beams.When the two InGaN/GaN MQW diodes are used as transmitter and receiver respectively,the in-plane 30 Mbps visible unidirectional transmission system is realized,and the ability of receiver to receive signals under different bias voltage is verified.The data indicate that the detection ability of the diode acting as a receiver is enhanced under turn on state.When the two suspended InGaN/GaN MQW-diodes simultaneously serve as the transmitter and the receiver,an in-plane full-duplex light communication is experimentally demonstrated with a transmission rate of 30 Mbps.