SWIR Imaging with Plasmonic Silicon Photodetectors
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Solution Overview
Problem
Current imaging systems operating in the visible and near-infrared wavelength ranges face significant performance reductions in extreme weather conditions and high ambient light, and are expensive when operating in the SWIR regime due to the use of non-silicon materials like InGaAs.
Innovation Solution
The development of Si-based imaging systems utilizing plasmonic enhanced pyramidal silicon Schottky photodetectors with embedded spiral lenses and orbital angular momentum (OAM) beams for active illumination, which operate in the SWIR wavelength range, enhancing image quality and reducing noise in adverse weather conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If InGaAs-based imaging systems are used for SWIR detection, then detection capability in SWIR regime is achieved, but system cost becomes inherently expensive
Solution Approach 1:
The patent changes the material parameter from InGaAs to silicon, and operates at different wavelength parameters (1350-1400 nm and 1450-1600 nm ranges) where silicon exhibits appropriate photodetection properties. This parameter change enables cost-effective SWIR imaging while maintaining detection capability.
Solution Approach 2:
The patent employs composite material structures including silicon photodetectors combined with plasmonic nanostructures (gold or aluminum nanoparticles). This composite approach enhances silicon's intrinsic SWIR response through plasmonic field enhancement, achieving InGaAs-level performance with cheaper silicon-based materials.
2Ease of manufacture
If visible or NIR imaging systems are used, then system cost is lower, but performance significantly reduces in extreme weather conditions like fog and dust
Solution Approach 1:
The patent changes the operating wavelength parameter from visible/NIR to SWIR regime (1350-1600 nm), where atmospheric scattering by water vapor, fog, and dust is reduced. This wavelength parameter change provides penetration advantage through adverse weather while maintaining cost-effectiveness using silicon-based detectors.
3Device complexity
If conventional imaging systems are used under high ambient light intensity, then system simplicity is maintained, but image quality becomes saturated and degraded
Solution Approach 1:
The patent changes the detection wavelength parameter to SWIR regime where the solar blind region provides natural background rejection. Silicon photodetectors at SWIR wavelengths experience reduced saturation from ambient visible light, maintaining image quality without requiring complex saturation compensation mechanisms.
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
These systems provide improved signal-to-noise ratio and image clarity in extreme weather and high light conditions, enabling effective object recognition and identification, while being more cost-effective than traditional SWIR systems.
Implementation Method 1
each PD includes an embedded spiral plasmonic lens that can focus and detect a specific value of a total OAM
Implementation Method 2
active illumination source for illuminating a target in a SWIR wavelength range with radiation in the form of an orbital angular momentum (OAM) beam
Implementation Method 3
each PD is operative to detect SWIR radiation reflected from the target and to convert the detected SWIR radiation into an electrical signal
Implementation Method 4
FPA of plasmonic enhanced pyramidal silicon Schottky photodetectors (PDs)
Data Source
AI summary
Focal plane arrays (FPAs) of plasmonic enhanced pyramidal silicon Schottky photodetectors (PDs) operative in the short wave infrared (SWIR) regime, and imaging systems combining such FPAs with active illumination sources and readout integrated circuit (ROIC). Such imaging systems enable imaging in the SWIR regime using inexpensive silicon detector arrays, specifically in vehicular environments in which such an imaging system may be mounted on a vehicle and image various moving and stationary targets.