How to Improve VCSEL Pulsed Measurement Accuracy

+ Modular PXIe Precision SMU

Reduce Narrow-Pulse Measurement Errors

Narrow-pulse Vertical Cavity Surface Emitting Laser (VCSEL) characterization requires controlling measurement errors introduced between the Source/Measure Unit (SMU) and device under test. Cable impedance can produce voltage drops, while cable inductance can affect the transient response and introduce overshoot. These effects become more significant during pulsed measurements and can cause the measured voltage or current waveform to differ from the response at the device.

The measurement setup requires voltage sensing closer to the device and a connection path suited for fast transient pulses. Comparing the measured transient response helps identify differences caused by the sensing configuration and cable characteristics. For short pulses, reducing cable inductance also produces a cleaner current pulse with less overshoot, improving the electrical conditions used for Light-Current-Voltage (LIV) characterization.

Accurate VCSEL Pulsed Measurement Solution

Accurate narrow-pulse VCSEL measurement requires reducing errors introduced by the connection between the measurement instrument and device under test. The Keysight Precision PXIe Source/Measure Unit (SMU) supports Remote Transient Voltage Measurement for fast transient pulsed voltage measurements with smaller measurement error. A dedicated measurement terminal reduces the influence of the SMU's internal circuit impedance and extends the voltage sensing point closer to the device. For pulses below 50 µs, the solution brief also recommends a specially designed low-inductance cable to reduce cable-related error and mitigate narrow-pulse overshoot, enabling a cleaner sourced current pulse.

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