VCSEL Laser Radar Substrate Segmentation for Signal Transmission
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Solution Overview
Problem
Current laser radar systems face challenges in efficiently transmitting and detecting laser beams emitted by vertical-cavity surface-emitting lasers (VCSELs) and backscattered by objects, particularly due to substrate opacity and electrical connectivity limitations.
Innovation Solution
The integration of an array of VCSELs on a first substrate with an array of detectors on a second substrate, where the substrates are bonded to allow laser beams to transmit through windows and vias provide electrical connections, enabling efficient detection using single photon avalanche diodes or photomultipliers, with circuitry for driving the VCSELs and detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first substrate is made opaque to block stray light, then the signal-to-noise ratio improves, but the laser beams cannot transmit through the substrate to reach the detectors
Solution Approach 1:
The first substrate is segmented into transparent regions (windows) and opaque regions. The transparent regions allow laser beams to pass through to the detectors while the opaque regions block stray light, thus simultaneously achieving signal transmission and noise reduction
Solution Approach 2:
Different regions of the first substrate have different optical properties: some regions are made transparent for laser beam transmission while other regions are made opaque for stray light blocking. This local differentiation of material properties resolves the contradiction between transmission and noise reduction
2Volume of moving object
If the substrates are bonded closely to reduce size, then the device compactness improves, but electrical connectivity between VCSELs and circuitry becomes difficult to establish
Solution Approach 1:
Electrical connections are established through the thickness dimension of the first substrate using conductive vias that extend from one surface to the other. This vertical connection approach allows compact bonding while maintaining electrical connectivity between VCSELs and circuitry on opposite sides of the substrate
3Ease of manufacture
If conventional edge-emitting semiconductor lasers are used, then the manufacturing process is simpler, but the laser beam emission direction is not perpendicular to the substrate surface
Solution Approach 1:
The laser emission geometry is changed from edge-emitting to surface-emitting by using VCSEL structure. This parameter change in emission direction enables perpendicular beam output from the substrate surface, which is essential for proper optical alignment in the laser radar system
4Productivity
If the first substrate is made entirely transparent to allow laser transmission, then the detection efficiency improves, but stray light enters the detector causing noise
Solution Approach 1:
The first substrate is divided into transparent windows for laser transmission and opaque regions for stray light blocking. This segmentation allows the system to achieve both high detection efficiency through the windows and noise reduction through the opaque barriers
Solution Approach 2:
The first substrate acts as an intermediary element that selectively transmits desired laser beams through its transparent windows while blocking harmful stray light through its opaque regions, thus mediating between the VCSELs and detectors
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
This configuration enhances the detection capability of laser radar systems by ensuring clear transmission of laser beams and reliable electrical connectivity, improving the accuracy and efficiency of distance measurement and imaging processes.
Implementation Method 1
A VCSEL may have an active region sandwiched between upper and lower Bragg reflectors (e.g., formed by epitaxial growth on a substrate). A VCSEL may be formed from materials such as GaAs, InGaAs, or AlGaAs.
Implementation Method 2
an array of detectors on a second substrate, the detectors configured to detect laser beams emitted by the VCSELs and backscattered by an object; wherein the first substrate is mounted to the second substrate and is configured to allow the laser beams emitted by the VCSELs and backscattered by the object to transmit through the first substrate and reach the detectors.
Data Source
AI summary
An apparatus comprises an array of vertical-cavity surface-emitting lasers (VCSELs) on a first substrate and an array of detectors on a second substrate, the detectors being configured to detect laser beams emitted by the VCSELs and backscattered by an object, wherein the first substrate is mounted to the second substrate and is configured to allow the laser beams emitted by the VCSELs and backscattered by the object to transmit through the first substrate and reach the detectors.