Frequency Selective IR Sensors with Plasmonic Angular Independence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current infrared (IR) sensors lack effective frequency selectivity and angular independence, limiting their ability to detect and convert IR radiation efficiently across various angles and frequencies, particularly in the mid-wave and long-wave IR spectral windows, which are crucial for defense and molecular vibration detection.
Innovation Solution
The development of frequency selective infrared (IR) sensors and focal plane arrays incorporating a frequency selective surface plasmonic (FSSP) structure, which includes a dielectric IR absorber, an electrode, and a patterned conductive layer to selectively transmit and convert IR radiation into surface plasmon waves (SPWs) independent of the angle of incidence, utilizing materials like gold, aluminum, and copper to support SPWs without excessive dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional IR sensors are used, then they can detect IR radiation, but they lack frequency selectivity and angular independence
Solution Approach 1:
The sensor is divided into distinct functional layers: a frequency selective surface (FSS) layer for frequency filtering, a plasmonic layer for angular-independent resonance, and a detector layer for signal conversion. This segmentation allows each layer to specialize in one function, achieving both frequency selectivity and angular independence simultaneously
Solution Approach 2:
The invention combines multiple materials with complementary properties: conductive materials (gold, aluminum, copper) for the FSS and plasmonic layers to support surface plasmon waves, dielectric materials for the substrate, and detector materials for IR signal conversion. This composite structure enables both frequency selectivity and angular independence
2Measurement precision
If frequency selective surfaces are added to improve frequency selectivity, then frequency discrimination improves, but device complexity increases
Solution Approach 1:
The frequency selective surface and plasmonic resonance structure are merged into a single integrated layer rather than separate components. This combination achieves frequency selectivity through the FSS pattern while simultaneously providing angular independence through plasmonic resonance, reducing overall device complexity compared to stacked filters
Solution Approach 2:
The plasmonic layer serves multiple functions simultaneously: it acts as a frequency filter, provides angular-independent resonance enhancement, and couples incident IR radiation to the detector. This multi-functionality reduces the need for additional separate components
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 FSSP structure enables efficient detection and conversion of IR radiation across specific frequency bands with improved angular independence, allowing for precise imaging and energy harvesting, while maintaining low reflection and transmission of the desired frequency band, even at near-grazing incidence angles.
Implementation Method 1
a frequency selective surface plasmonic (FSSP) structure... The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band... The FSSP structure is designed to selectively convert radiation in the predetermined frequency band that is incident on the FSSP structure into surface plasmon waves (SPWs)
Implementation Method 2
a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface
Data Source
AI summary
A frequency selective infrared (IR) photodetector having a predetermined frequency band. The exemplary frequency selective photodetector includes: a dielectric IR absorber having a first surface and a second surface substantially parallel to the first surface; an electrode electrically coupled to the first surface of the dielectric IR absorber; and a frequency selective surface plasmonic (FSSP) structure formed on the second surface of the dielectric IR absorber. The FSSP structure is designed to selectively transmit radiation in the predetermined frequency band that is incident on the FSSP structure substantially independent of the angle of incidence of the incident radiation on the FSSP structure.