Optical Antenna With Periodic Dielectric Structures for High Radiation Efficiency
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Solution Overview
Problem
Existing optical phased arrays face limitations in detection distance due to on-chip loss, antenna radiation efficiency, and effective radiation aperture, particularly with commercial SOI wafer structures that suffer from energy leakage to the substrate and limited radiation length.
Innovation Solution
The optical antenna design features a waveguide with periodically arranged first and second dielectric structures on both sides and above the waveguide, respectively, with a displacement offset. These structures disturb the evanescent field, generating interfering radiation light fields that cancel under the waveguide, radiating energy efficiently into free space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a grating antenna is designed based on a commercial SOI wafer structure without a bottom plate, then the structure is simple and compatible with CMOS process, but nearly half energy leaks to the substrate side resulting in low radiation efficiency
Solution Approach 1:
The patent converts the harmful energy leakage to the substrate into a beneficial effect by using the substrate as a reflective surface. The periodic dielectric structures are designed to create constructive interference for upward radiation while the substrate reflection provides additional constructive interference, effectively turning the energy loss pathway into an enhancement mechanism for radiation efficiency
Solution Approach 2:
The patent introduces periodic dielectric structures as intermediary elements between the waveguide and the substrate. These structures mediate the electromagnetic field distribution to achieve constructive interference in the upward direction while maintaining CMOS process compatibility, thus improving radiation efficiency without requiring a complex bottom plate structure
2Ease of manufacture
If direct etch is performed on the upper surface or side wall of a waveguide, then the manufacturing process is simple, but strong radiation occurs resulting in limited effective radiation length and large 3 dB beam width
Solution Approach 1:
The patent applies local quality by positioning periodic dielectric structures only at specific locations (outside and above the waveguide) rather than etching the entire waveguide surface. This localized approach creates the necessary radiation conditions while preserving the waveguide's overall integrity and achieving narrow beam width through controlled interference patterns
3Loss of energy
If a DBR bottom plate is used to achieve high-efficiency radiation, then radiation efficiency improves, but the structure becomes complicated and incompatible with CMOS process
Solution Approach 1:
The patent extracts the essential function of the DBR bottom plate (providing reflective enhancement for radiation efficiency) and implements it through a simplified periodic dielectric structure that is compatible with CMOS process. This extraction removes the complex multi-layer DBR structure while retaining the key benefit of enhanced radiation efficiency through interference control
4Shape
If dielectric blocks are arranged to disturb evanescent field for radiation, then directional beam is achieved, but radiation intensity is reduced greatly and bandwidth is narrow
Solution Approach 1:
The patent merges two periodic dielectric structure arrangements (one outside the waveguide and one above the waveguide) to simultaneously achieve directional beam formation and maintain high radiation intensity. The combined structures create constructive interference patterns that enhance both directionality and radiation intensity, overcoming the limitation of reduced intensity in single-arrangement designs
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 design achieves high radiation efficiency and directivity, allowing for a longer detection range and a narrow 3 dB beam width, while being compatible with the CMOS process and simplifying manufacturing.
Implementation Method 1
the plurality of first dielectric structures and the plurality of second dielectric structures disturb an evanescent field around the waveguide
Implementation Method 2
the two radiation light fields interfere with each other before being cancelled under the waveguide
Implementation Method 3
a waveguide; a plurality of first dielectric structures, arranged outside both sides of the waveguide respectively
Data Source
AI summary
Optical antenna includes waveguide; first dielectric structures are arranged outside two sides of waveguide respectively and are symmetrically and periodically arranged in light propagation direction; second dielectric structures are arranged on two sides of upper portion of waveguide respectively and are symmetrically and periodically arranged in light propagation direction; waveguide, first dielectric structures and second dielectric structures are isolated by third dielectric, periodic size of first dielectric structures is consistent with periodic size of second dielectric structures, and first dielectric structures and second dielectric structures have certain relative displacement deviation in light propagation direction; evanescent field around waveguide is disturbed through first dielectric structure and second dielectric structure, so that two correspondingly generated radiation light fields cancel interference below waveguide, and radiation energy is radiated to upper free space side. According to invention, free space side high radiation efficiency and far field high directivity wave beams can be realized.