CMOS Plenoptic Sensor with Grating Couplers for Spectral Angular Resolution
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Solution Overview
Problem
Current smart lighting technologies face challenges in achieving high spectral and angular sensitivity with color pixels integrated onto silicon surfaces, requiring sophisticated control systems and manufacturing processes that are not scalable or cost-effective, especially due to silicon's varying absorption across the visible spectrum.
Innovation Solution
The development of a CMOS-compatible plenoptic sensor using grating coupling to bound modes propagating on a metal surface, which can be coated with silica, allowing photons to tunnel through to an underlying silicon p-n junction, and a 2-D sensor array with a slab waveguide structure and grating couplers for spectral and angular filtering, enabling both spectral and angular sensitivity with reduced form factors and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface plasma wave enhancement is used in the visible spectrum, then spectral resolution can be improved, but metal optical losses restrict bandwidth and transmission is low
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the metal surface and the incident light. This dielectric layer modifies the plasmonic resonance conditions, allowing for enhanced spectral resolution while reducing the direct interaction between light and lossy metal, thereby mitigating optical losses and bandwidth restrictions
Solution Approach 2:
The patent modifies the plasmonic structure parameters by introducing dielectric materials with specific refractive indices and adjusting the geometric parameters of the metal-dielectric system. This changes the resonance conditions to achieve narrow bandwidths (order of 10 nm) while maintaining high transmission and reducing optical losses
2Ease of manufacture
If traditional color camera filters are used, then manufacturing is simple, but angular insensitivity and broad spectral bandwidth prevent high spectral and angular resolution
Solution Approach 1:
The sensor is divided into multiple pixels, with each pixel equipped with a specific plasmonic filter structure tuned to detect particular wavelengths and angles. This segmentation allows each pixel to have narrow spectral bandwidth (order of 10 nm) and specific angular sensitivity, achieving high resolution while maintaining CMOS compatibility for manufacturability
Solution Approach 2:
The plasmonic filter structure serves multiple functions simultaneously: it provides spectral filtering, angular sensitivity, and enhanced light-matter interaction. This multi-functionality is achieved within a single integrated pixel structure that remains compatible with standard CMOS manufacturing processes
3Adaptability or versatility
If silicon absorption is utilized across the visible spectrum, then detection coverage is comprehensive, but varying absorption creates non-uniform sensitivity
Solution Approach 1:
The plasmonic filter structures are designed with locally optimized parameters for different spectral regions. By adjusting the geometric parameters and material composition of the metal-dielectric structures at different locations, the patent achieves enhanced and more uniform sensitivity across the entire visible spectrum, compensating for silicon's varying absorption characteristics
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 solution provides a CMOS-compatible photodetector with spectral resolution of approximately 30 nm and angular resolution of 100 mrad, suitable for LED lighting applications, achieving efficient spectral and angular separation and enabling scalable, cost-effective mass production while maintaining high sensitivity and resolution.
Implementation Method 1
grating coupling to bound modes propagating on a metal surface, which can be coated with silica, allowing photons to tunnel through to an underlying silicon p-n junction
Implementation Method 2
allowing photons to tunnel through to an underlying silicon p-n junction
Implementation Method 3
a 2-D sensor array with a slab waveguide structure and grating couplers for spectral and angular filtering
Implementation Method 4
a 2-D sensor array with a slab waveguide structure and grating couplers for spectral and angular filtering
Implementation Method 5
underlying silicon p-n junction
Data Source
AI summary
A 2-D sensor array includes a semiconductor substrate and a plurality of pixels disposed on the semiconductor substrate. Each pixel includes a coupling region and a junction region, and a slab waveguide structure disposed on the semiconductor substrate and extending from the coupling region to the region. The slab waveguide includes a confinement layer disposed between a first cladding layer and a second cladding layer. The first cladding and the second cladding each have a refractive index that is lower than a refractive index of the confinement layer. Each pixel also includes a coupling structure disposed in the coupling region and within the slab waveguide. The coupling structure includes two materials having different indices of refraction arranged as a grating defined by a grating period. The junction region comprises a p-n junction in communication with electrical contacts for biasing and collection of carriers resulting from absorption of incident radiation.