Radiation Sensor Photonic Crystal Nanostructure Impedance Matching

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Solution Overview

Problem

Current radiation sensors face challenges in achieving high transmission and resolution due to total internal reflections and refractive index mismatches at the scintillator-photodetector interface, leading to signal loss and degraded energy and timing resolution.

Innovation Solution

The implementation of adiabatic gradient-index photonic crystal nanostructures, such as nanocones, which provide impedance matching and efficient light transfer by varying the refractive index gradually, reducing reflections and enhancing transmission across a broad range of wavelengths and angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If multi-layer coatings are used to improve transmission at the scintillator-photodetector interface, then transmission is improved, but manufacturing complexity and cost increase significantly for high-end applications

Engineering Contradiction:

Improvelight transmission lossVSAvoidmanufacturing complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The interface is segmented into multiple thin layers with progressively changing refractive indices, transitioning from the high-index scintillator material through intermediate layers to the low-index photodetector window. This segmentation allows gradual impedance matching without requiring complex multi-layer coatings, reducing manufacturing complexity while maintaining high transmission efficiency across broad bandwidths and angles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The refractive index parameter is changed gradually across the interface by using materials with intermediate indices or by structuring the interface to create an effective gradient. This parameter change approach eliminates the need for precise multi-layer coating thickness control, simplifying manufacturing while achieving superior transmission compared to conventional MLCs.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional flat interface is used between scintillator and photodetector, then manufacturing is simple, but total internal reflections cause signal loss and degraded resolution

Engineering Contradiction:

Improveinterface fabrication simplicityVSAvoidenergy and timing resolution

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The interface structure is modified locally at the scintillator-photodetector boundary to create a gradient-index region. This local modification improves light transmission and resolution without affecting the bulk properties of the scintillator or photodetector, maintaining manufacturing simplicity while enhancing performance through targeted structural optimization at the critical interface region.

Inventive Principle:

Principle #3Local quality

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 approach results in significant gains in light collection efficiency, energy resolution, and timing resolution, making the radiation sensor performance comparable to or exceeding that of cooled semiconductor sensors, with improvements in spatial and temporal resolution.

Implementation Method 1

adiabatic gradient index lens structure... which provide impedance matching and efficient light transfer by varying the refractive index gradually, reducing reflections and enhancing transmission

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

the light generated by the interaction of a γ-ray in the scintillator undergoes multiple total internal reflections and losses before exiting to the photodetector

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

the use of a single layer whose effective index of refraction is specified by periodic 'drilling' of subwavelength holes in a high-index medium substrate. Because the holes are smaller than the wavelength, they do not diffract or otherwise affect light transmission

Methodology Applied

Scientific EffectPhotonic crystal: Photonic Crystal

Implementation Method 4

the light generated by the interaction of a γ-ray in the scintillator

Methodology Applied

Scientific EffectScintillation: Scintillation

Data Source

PatentUS9377542B1Radiation sensor having photonic crystal structure and fabrication method thereof

Publication Date: 2016.06.28 RADIATION MONITORING DEVICES INC

AI summary

A radiation sensor and a fabrication method thereof are described. In one aspect, the radiation sensor comprises a photo detector, a scintillator on the photo detector, and an adiabatic gradient-index photonic crystal nanostructure between the scintillator and the photo detector. In one instance, the adiabatic gradient-index photonic crystal nanostructure comprises an impedance matching nanostructure. In another instance, the adiabatic gradient-index photonic crystal nanostructure comprises a plurality of nanocones.