Dual-Polarization LiDAR Waveguide Splitter for Polarization Mismatch
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Solution Overview
Problem
Monostatic LiDAR systems face inefficiencies in receiving backscattered light due to polarization mismatch and varying reflectivity of objects, leading to incomplete detection of polarized light, especially when backscattered light returns with a different polarization or has unequal reflectivity for TE and TM polarizations.
Innovation Solution
The LiDAR system employs polarization-based waveguide splitters, optical emitters, and a controller to route light through dual-polarization waveguides, optionally with a polarization rotator and birefringent materials, to ensure efficient detection of both TE and TM polarized light by optimizing grating couplers and using birefringent elements for spatial mode alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If monostatic LiDAR systems use single-polarization optics to send excitation pulses and collect return signals, then the system structure is simplified, but the detection efficiency of backscattered light with different polarizations is reduced
Solution Approach 1:
The LiDAR system is segmented into separate transmit and receive optical paths with independent polarization handling. The transmit path uses a first polarization state while the receive path is configured to detect both polarization states, allowing efficient detection without requiring the entire system to handle complex polarization states simultaneously.
Solution Approach 2:
The receive optics are designed with multi-functionality to detect both TE and TM polarized light, while the transmit optics maintain single-polarization simplicity. This universal detection capability ensures that regardless of the polarization state of backscattered light, the system can efficiently receive and process the signals.
2Measurement precision
If LiDAR optics are optimized for a specific polarization state, then the performance for that polarization is improved, but the ability to receive other polarization states is compromised
Solution Approach 1:
Different parts of the optical system have different polarization handling characteristics. The transmit optics are optimized for a specific polarization state (local optimization), while the receive optics are designed to accept both polarization states (universal acceptance). This local quality differentiation allows each component to excel at its specific function while the system as a whole achieves versatile polarization detection.
Solution Approach 2:
The system transitions from a single-polarization detection approach to a dual-polarization detection approach by adding an additional polarization dimension to the receive path. This is achieved through specific optical component arrangements that enable independent detection of TE and TM polarized light, effectively adding a dimension to the detection capability.
3Reliability
If the LiDAR system uses separate optics for transmitting and receiving light, then the detection of different polarizations is improved, but the system complexity and size increase
Solution Approach 1:
The system merges the transmit and receive optics into a shared optical path where possible, using the same physical optics for both functions but configuring them to handle different polarization states. This merging reduces the overall number of components and simplifies the system architecture while maintaining the ability to detect different polarizations through careful optical design.
Solution Approach 2:
Polarization-selective components act as intermediaries that direct different polarization states to appropriate detection paths. These intermediary elements enable the system to handle multiple polarization states without requiring completely separate optical paths for each polarization, thus reducing overall system complexity.
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 efficiency of LiDAR systems by ensuring that both polarizations of backscattered light are effectively received, improving the system's ability to detect objects with varying polarization reflectivity, such as transparent objects at grazing angles.
Implementation Method 1
Each polarization-based waveguide splitter has a first splitter port, a second splitter port and a common splitter port... optically coupled to the first splitter port via a single-polarization waveguide... optically coupled to the second splitter port via a dual-polarization waveguide
Implementation Method 2
optimizing grating couplers and using birefringent elements for spatial mode alignment
Implementation Method 3
optionally with a polarization rotator and birefringent materials, to ensure efficient detection of both TE and TM polarized light
Data Source
AI summary
A LiDAR system has a field of view and includes a polarization-based waveguide splitter. The splitter includes a first splitter port, a second splitter port and a common splitter port. A laser is optically coupled to the first splitter port via a single-polarization waveguide. An objective lens optically couples each optical emitter of an array of optical emitters to a respective unique portion of the field of view. An optical switching network is coupled via respective dual-polarization waveguides between the common splitter port and the array of optical emitters. An optical receiver is optically coupled to the second splitter port via a dual-polarization waveguide and is configured to receive light reflected from the field of view. A controller, coupled to the optical switching network, is configured to cause the optical switching network to route light from the laser to a sequence of the optical emitters according to a temporal pattern.