Vertical Laser-Photodetector Stack for Low-Power FMCW Distance Sensing
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Solution Overview
Problem
Current LIDAR systems, particularly FMCW LIDAR systems, face challenges in reliably detecting objects at greater distances due to the need for high-power laser light sources, and there is a need for improved optoelectronic semiconductor devices and sensors for enhanced distance and object recognition capabilities.
Innovation Solution
An optoelectronic semiconductor device and apparatus featuring a semiconductor layer stack with a surface-emitting laser diode and photodetector arranged vertically, utilizing a waveguide for aligned electromagnetic radiation, and an evaluation device to determine distance changes based on frequency differences in emitted and reflected radiation, with a current source varying the emission wavelength and a method for operating these devices to determine positional relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-power laser light sources are used to detect objects at greater distances, then the detection range is improved, but the energy consumption and power requirements increase
Solution Approach 1:
The patent combines the laser diode and photodetector into a single vertical cavity structure where the photodetector is positioned directly below the laser diode. This integration allows the reflected light to be detected immediately within the same device structure, improving detection efficiency and enabling greater detection ranges while reducing the need for high-power sources.
Solution Approach 2:
The patent transitions from a lateral arrangement of laser and detector to a vertical arrangement with the photodetector positioned beneath the laser diode in the same semiconductor layer. This vertical configuration optimizes the optical path for detecting reflected light and enables more efficient use of the emitted radiation, improving detection capability without proportionally increasing power consumption.
2Measurement precision
If high-power laser light sources are used to detect objects at greater distances, then the detection range is improved, but the device complexity and power supply requirements increase
Solution Approach 1:
The patent merges the laser generation and light detection functions into a single integrated semiconductor device. The vertical cavity structure combines the laser diode, photodetector, and waveguide into one compact unit, simplifying the overall system architecture and reducing power supply complexity compared to separate high-power laser systems.
Solution Approach 2:
The semiconductor device performs multiple functions within a single structure: the laser diode emits coherent light, the waveguide directs the light toward the target, and the photodetector detects the reflected light. This multi-functionality eliminates the need for separate components and simplifies the power supply requirements.
3Measurement precision
If the laser diode and photodetector are arranged vertically in the same semiconductor layer, then the wavefront alignment and superposition are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent combines the laser diode and photodetector into a single vertical cavity structure grown in one semiconductor layer. This monolithic integration ensures that both components are automatically aligned during the semiconductor growth process, achieving precise wavefront alignment without requiring post-fabrication adjustment and reducing the impact of manufacturing tolerances.
Solution Approach 2:
The photodetector is positioned within the vertical cavity structure directly beneath the laser diode, creating a nested configuration where the detection element is embedded in the same semiconductor layer. This nesting ensures automatic alignment of the optical paths and wavefronts while simplifying the manufacturing process.
4Measurement precision
If a waveguide is used to supply reflected electromagnetic radiation to the photodetector, then the detection sensitivity is improved, but the device complexity increases
Solution Approach 1:
The waveguide is integrated directly into the vertical cavity structure, forming a unified optical path from the laser diode through the waveguide to the photodetector. This integration improves detection sensitivity by efficiently guiding the reflected light while avoiding the need for separate, complex external waveguide systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise detection of small changes in distance and relative speed with high sensitivity, achieving a resolution in the micrometer range and allowing for the use of lower power while maintaining effective object recognition and distance measurement.
Implementation Method 1
a surface-emitting laser diode (103) and a photodetector (105), which are arranged vertically one above the other
Implementation Method 2
information about a change in distance between the optoelectronic semiconductor device and an object which has reflected the electromagnetic radiation emitted by the laser diode
Implementation Method 3
The optoelectronic semiconductor device may further comprise a waveguide which is adapted to supply electromagnetic radiation reflected by an object to the photodetector
Implementation Method 4
In this manner, the wavefronts of the electromagnetic radiation emitted by the surface-emitting laser diode and of the radiation reflected by the object may be aligned particularly well. When the respective wavefronts are aligned, superimposition of the electromagnetic radiation and thereby mixing are promoted
Implementation Method 5
the photodetector is adapted to detect the reflected electromagnetic radiation
Implementation Method 6
LIDAR ('Light Detection and Ranging') systems, in particular FMCW LIDAR systems ('Frequency Modulated Continuous Wave' LIDAR systems) are increasingly being used in vehicles
Implementation Method 7
information about a change in distance between the optoelectronic semiconductor device and an object which has reflected the electromagnetic radiation emitted by the laser diode
Data Source
AI summary
An optoelectronic semiconductor component (10) includes a semiconductor stack (109) in which a surface-emitting laser diode (103) and a photodetector (105) are placed vertically on top of one another. The optoelectronic semiconductor component (10) additionally includes an electric power source (149) that is adapted to modify a current intensity applied to the surface-emitting laser diode (103), thus allowing an emission wavelength to be modified.