Electroabsorption Modulator Cavity-Free Design for TOF Depth Imaging
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Solution Overview
Problem
Conventional TOF depth imaging systems employing electro-optic shutters have limitations such as small numerical aperture, high power consumption, and limited depth and lateral resolution, which restrict their commercial use and applications.
Innovation Solution
The use of electroabsorption modulators with delocalized electron-hole behavior and a thick active layer, eliminating the need for optical cavities, allows for higher numerical aperture, reduced power consumption, and improved depth and lateral resolution, enabling wider field of view and higher modulation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If electro-optic shutters are used in TOF depth imaging systems, then the system can achieve depth imaging functionality, but the numerical aperture is small and the field of view is limited
Solution Approach 1:
The patent removes the optical cavity structure from the modulator design, extracting only the essential active layer with delocalized electron-hole behavior. This elimination of the optical cavity enables larger numerical aperture and wider field of view while maintaining modulation functionality.
Solution Approach 2:
The patent changes the fundamental operating parameters by utilizing delocalized electron-hole behavior in the active layer, which allows the modulator to function without an optical cavity. This parameter change enables both larger numerical aperture and simplified structure simultaneously.
2Power
If electro-optic shutters with optical cavities are used, then modulation can be achieved, but power consumption is high
Solution Approach 1:
The patent extracts and removes the optical cavity component, eliminating the primary source of high power consumption associated with cavity-based electro-optic shutters. The remaining active layer with delocalized electron-hole behavior maintains reliable modulation performance at lower power levels.
Solution Approach 2:
By changing the modulation mechanism to rely on delocalized electron-hole behavior rather than cavity resonance, the patent achieves both reduced power consumption and maintained modulation reliability through a fundamentally different operating regime.
3Measurement precision
If conventional electro-optic shutters are used, then depth imaging is possible, but depth resolution and lateral resolution are limited
Solution Approach 1:
The patent removes the optical cavity structure that limits resolution performance, allowing the active layer with delocalized electron-hole behavior to directly provide both simplified structure and improved depth resolution and lateral resolution.
Solution Approach 2:
The patent changes the fundamental behavior parameter to delocalized electron-hole behavior, which simultaneously improves measurement precision (depth and lateral resolution) while eliminating the need for complex optical cavity structures.
4Area of moving object
If optical cavities are used in modulators, then modulation can be achieved, but the field of view is restricted and telecentric lenses are required
Solution Approach 1:
The patent extracts and eliminates the optical cavity, which is the component that necessitates telecentric lenses and restricts field of view. The resulting cavity-less design with delocalized electron-hole behavior naturally supports wider fields of view without requiring specialized lens configurations.
Solution Approach 2:
By changing the modulation mechanism to delocalized electron-hole behavior, the patent removes the constraint that required telecentric lenses, thereby enabling both larger numerical aperture and wider field of view with standard optical 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 electroabsorption modulators provide enhanced depth and lateral resolution, lower power consumption, and a wider field of view, making them suitable for applications in consumer electronics, robotics, and machine vision without the need for telecentric lenses.
Implementation Method 1
The quantum wells are configured to exhibit delocalized electron-hole behavior and are surrounded by an optical cavity to enhance the quantum confined stark effect.
Data Source
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AI summary
A TOF depth imaging system for providing a depth image of an object is provided comprising a light source configured to illuminate an object with amplitude modulated light characterized by a wavelength λ and a modulation frequency f; a surface-normal electroabsorption modulator configured to receive and to modulate reflected light from the object with the modulation frequency f, and an image sensor configured to receive and to detect modulated reflected light from the electroabsorption modulator. The electroabsorption modulator comprises a top doped layer of semiconductor, a bottom doped layer of semiconductor having opposite polarity to the top doped layer, and an active layer between the top and bottom doped layers, the active layer configured as a superlattice structure comprising multiple sublayers of semiconductor configured to provide alternating quantum wells and barriers, the active layer comprising quantum wells configured to exhibit delocalized electron-hole behavior.