Design And Research On Electrode Transmission Lines Of High-speed Photodetectors In Optical Communication

As a core device in optical receivers,photodetector(PD),bears the important task of photoelectric conversion.As with the spread of information technology,high-speed and ultra-high-speed is a demanding target for fiber optic communication systems.Hence,PDs with High-speed response and high-power photoelectric conversion are requisite.There are numerous limits for high-power optical signals reception of single PD.A better solution is receiving optical signals by an array architecture consisting of several discrete PDs.The preponderance of photodetector array(PDA)structure mentioned above is not only defusing the exact demands of performance of single PD,but also overcoming the trade-off between high-speed and high power of the overall structure.Moreover,signal processing by allocating to each cell can release the heating effects and improve service lives of devices.The mission of electrode transmission lines of PD is transmitting the electrical signals generated by PDs to the output end.Note that the performance of overall structure will be severely affected by parasitic parameter and impedance discontinuity caused by undesirable design of electrode transmission lines.More importantly,the layout of electrode transmission lines determines the placement and integrated manners of PDs.In these circumstances,the design,optimization,fabrication and test of the structure of electrode transmission lines of PD and PDA are studied in this dissertation.The main achievements are summarized as follows:1.The basic theory of PD,PDA and electrode transmission lines of those two is studied.The present research on design for PDA at home and abroad is compared.Further,the defects of tradition structure,Traveling-Wave Photodiode Array(TW-PDA),are analyzed.2.The electrode transmission line of single PD is designed according to the microwave theories and methods.Further,its model is simulated and optimized by computer software.The result shows that final structure can hold the characteristic impedance on 50? among 1 GHz?100GHz,and has a forward transmission coefficient with-1.3dB at 100GHz.3.A Fork Photodiode Array(F-PDA)electrode transmission lines are presented to address the issues brought by transmission delay of TW-PDA,which cause phase-mismatches of electrical signals and affect the overall frequency response.The result shows that the structure of two-element and three-element has a forward transmission coefficient with-1.37dB and-1.76 dB at 100GHz respectively.4.A series of electrode transmission lines of PD and PDA which have been designed and optimized previously are fabricated.Moreover,measurement system is established successfully.The experimental result shows that the electrode transmission line of single PD has a forward transmission coefficient with-1.37dB at 40GHz,and the forked structure has a better performance compared with the traditional structure.Two-element structure has an improvement in 0.95dB,correspondingly,three-element one improves 0.84dB.Vertical comparison shows that there is a slight decline in performance when adding the branches of novel structure.