A Microring Modulator Integrated With An Optical Power Monitor

With the rapid development of information technology,electrical interconnection has encountered bottlenecks,optical interconnection came into being.Silicon photonics is a popular research direction in optical interconnection.Devices using microring resonator on silicon play an important role in optical interconnects because of their high Q,small size,and low power consumption.Due to the high thermal coefficient of silicon and the resonant characteristics of the microring,the working state of the microring is very susceptible to thermal interference,thus a feedback system needs to be established to lock the resonant wavelength.In the feedback system,the optical power monitor is an important part,as it can extract the working status of the microring,and monitor and control the microring resonant wavelength.This paper presents an optical power monitor that can be integrated in a microring modulator and performs experimental verification.The main work includes the following aspects:1.Based on the defect-mediated absorption mechanism,an optical power monitor integrated in a microring modulator is designed.A part of the microring is used for photoelectric detection,and residual defects which are produced in the process flow of a carrier-depletion-based microring modulator,are able to execute defect-mediated absorption and generate photocurrent.Furthermore,the doping compensation is performed by overlapping the ion implantation window so as to widen the depletion layer to enhance the device performance.The method of controlling variables is used to design microring-based devices and rib-waveguide-based devices on the above structure.2.Based on the previous work,a further experimental study has been conducted on the rib-waveguide-based optical power monitoring device using doping compensation,to determine the effect of doping compensation on the electrical characteristics and high speed performance of the device.The PN junction capacitance,dark current,eye diagram and bit error rate were tested.The test results of the PN junction capacitance and dark current are in line with the expectations;eye diagram and bit error rate measurement under high speed conditions show that the performance of 0.2μm is the best among devices with different overlapping widths of 0,0.2 and 0.4μm,which can perform an error-free transmission at 10Gbit/s,and conducted a theoretical analysis.3.The microring modulator devices integrated with an optical power monitor are studied experimentally,the power spectrum of the modulation area of microring is measured and fitted by the formula,the modulation characteristics of the microring devices are verified;dark current was measured to determine the location of the avalanche voltage;the responsivity of the detection area was measured,and the fact that the area can be used for photodetection is proved.Among devices of different overlap widths of 0,0.2,0.4,0.6p,m,the performance of 0.4μm is the best,and the responsivity above 1mA/W can be achieved without the carrier multiplication effect under a reverse bias voltage of-8V,and the theoretical analysis is carried out.The high speed link is set up to study the high speed characteristics of the microring devices.It is proved that the device can work under the speed of 10Gbit/s.The feedback locking scheme of the microring device is determined.The feedback signal is determined by Lab VIEW control program,and the microring resonant wavelength is changed by the variety of voltage of applied TEC.