Hetero-integration enables fast switching time-of-flight sensors for light detection and ranging

Abstract

The time-of-flight (ToF) principle is a method used to measure distance and construct three-dimensional (3D) images by detecting the time or the phase difference between emitted and back-reflected optical flux. The ToF principle has been employed for various applications including light ranging and detection (LiDAR), machine vision and biomedical engineering; however, bulky system size and slow switching speed have hindered the widespread application of ToF technology. To alleviate these issues, a demonstration of hetero-integration of GaN-based high electron mobility transistors (HEMTs) and GaAs-based vertical cavity surface emitting lasers (VCSELs) on a single platform via a cold-welding method was performed. The hetero-integrated ToF sensors show superior switching performance when compared to silicon-transistor-based systems, miniaturizing size and exhibiting stable ranging and high-resolution depth-imaging. This hetero-integrated system of dissimilar material-based highperformance devices suggests a new pathway towards enabling high-resolution 3D imaging and inspires broader range application of heterogeneously integrated electronics and optoelectronics.

Top-Emitting 940-nm Thin-film VCSELs Transferred Onto Aluminum Heatsinks

“…onto the aluminum heatsink using a probe station. The invisible laser emission of the 940-nm thin-lm VCSELs at injection current of 8 mA was observed to be a purple beam using a conventional microscope 5 . As can be seen from Fig.…”

“…Figure4(c) shows an optical microscopy image of the fabricated 940-nm top-emitting thin-lm VCSELs onto the aluminum heatsink using a probe station. The invisible laser emission of the 940-nm thin-lm VCSELs at injection current of 8 mA was observed to be a purple beam using a conventional microscope5 . As can be seen from Fig.4(d), the peak wavelength of the emitting light from the thin-lm VCSELs was 941 nm which corresponded to the sharp re ectance dip near 940 nm shown in Supplementary FigureS1.…”

High-Speed and High-Power 940 nm Flip-Chip VCSEL Array for LiDAR Application

“…The resolution of LiDAR imaging depends on the light modulation speed and contrast of the device [25]. The excellent thermal dissipation of the flip-chip VCSEL makes it more competitive in high-power applications because it reduces unnecessary losses caused by heat, and even enhances the modulation response speed.…”

Virtual laser scanning with HELIOS++: A novel take on ray tracing-based simulation of topographic 3D laser scanning

“…The fourth category summarises publications concerned with the development of novel sensors and methods, such as Park et al (2020), who present a new Time-of-Flight sensor and compare its results to a HELIOS simulation. In general, the parameters of the virtual sensors can be tuned to resemble a non-existent sensor, the performance of which can then be simulated without the need of actually building a prototype.…”