ViP stands for a VCSEL with integrated photodiode. It features a photodiode embedded in the VCSEL resonator. A single intra-cavity contact serves as VCSEL cathode as well as photodiode anode. The VCSEL is single-mode and a sub wavelength grating on the output facet is used to stabilize the polarization of the emitted light. The ultra-compact chip has two separately addressable mesas. In addition, good production capability and reliability make the device ideal for mass products. Exploiting the principle of self-mixing interference (SMI), the ViP can be used in systems precisely measuring e.g., velocity, distance, quantitative particle concentration as a measure for air quality or fast eye-movements. The interferometric precision of velocity measurements enables demanding industrial applications like a new contactless encoder with high accuracy. ViP and the SMI principle make the detection almost insensitive for environmental background light. The functionality of the sensor has been demonstrated in bright sunlight and measuring speed over ground up to 250km/h in automotive applications. Low latency is ideal for the detection of fast eye movements. The miniature sensor fits into the frame of an AR/VR goggle and can detect eye-gestures. An ultra-compact air quality detector measuring PM2.5 as well as ultra-fine particles is described as well. The system does not require any enforced air flow nor openings in the body thus could be embedded in wearable consumer devices. With a size of a match head, it enables a precise, real-time, and personalized measurement.
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