Research On VCSEL Based Probing Method For Effects Diagnosis In System Level HPEM Susceptibility Test

In this dissertation,vertical cavity surface emitting laser(VCSEL)based probing methods for diagnosing electronical equipment’s HPEM effects are proposed and studied.The original intention of this work is to capture HPEM induced damage,disturbs and other effects,while meeting the stringent requirements of system-level HPEM stress tests,such as maintaining the EUT’s electromagnetic integrality and causing as slight as possible instrusion to the EUT’s normal operation.Based on careful analysis of system-level HPEM test’s technical requirement,this study’s only focus is set as designing voltage probes with compact size and optical fiber output to achieve remote monitoring of EUT’s running-signals and capture HPEM induced signal abnormity in electronic equipments for HPEM effects diagnosing.VCSEL is selected among common optical sensing approaches such as EO effect,EA effect and so on to design the probes,as it offers many advantages required for designing compact sensors with fiber output,such as low power consumption,optical output,and high bandwidth simultaneously.A circuit level model of vertical-cavity surface-emitting laser is implemented in the Advanced Design System(ADS)computer-aided design environment.New normalization method and thermal leakage current expression are proposed to rate equations to improve numerical convergence of the model’s output part,which is critical for pulsed working condition.A real device’s model parameters are extracted and its voltage-current-light(V-I-L)curves,small-signal transfer function and transient response under pulsed driving condition are calculated by the model.The proposed model is a well preparation for designing HPEM sensor including VCSEL and other high frequency devices.The method of using bias-free VCSELs for monitoring pin voltage signal of digital ICs is proposed.Simulations with the VCSEL model and standard IBIS model for I/O ports of digital ICs,as well as experiment taken on a mini sized drone validate that bias-free VCSELs can be lighted up and convey I/O ports’ states in real time,while its load effects to the I/O ports are light enough not todeteriorate its signal integrity or disturb the circuit’s normal operation.VCSEL based voltage probes for 5V / 3.3V logic family ICs are designed with properly selected devices and optimized driving current to achieve high input impedance and high applicable data bit rate(BR)simultaneously.Measurement results show that the VCSEL based voltage probe’s input impedance can maintains higher than 1 kΩ until 300 MHz,whose load effects to most digital ICs are accessible.The probe is applicable for monitoring digital signals with BR below280 Mbps,while the monitoring bit error ratio(BER)is better than 1E-6 for BR below 200 Mbps.The happening processes of disturbance and upset effects induced to a mini sized drone circuit are successfully captured by the voltage probe in a pulse injection test.The study proposed a practical route of designing probes with compact size and optical fiber output for diagnosing HPEM effects in system-level test.