Optical Antenna Reflective Sidewall Grating Coupler
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Solution Overview
Problem
Conventional vertically oriented optical grating couplers in photonic integrated circuits (PICs) have a limited range of emission angles, resulting in a restricted field of view and insufficient signal fidelity, particularly in applications like LiDAR.
Innovation Solution
An optical antenna design featuring a vertically oriented semiconductor waveguide with a reflective material along one sidewall and a plurality of grating protrusions on the opposite sidewall, along with a dielectric layer interdigitating with the grating protrusions, enhances coupling efficiency by expanding the field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional vertically oriented optical grating couplers are used, then the structure is simple and easy to manufacture, but the field of view is restricted and signal fidelity is insufficient
Solution Approach 1:
The optical antenna is segmented into distinct functional components: a vertically oriented semiconductor waveguide, reflective material applied to sidewalls, and grating protrusions formed on the waveguide surface. This segmentation allows each component to be optimized independently while working together to expand the field of view beyond conventional limitations.
Solution Approach 2:
Different regions of the optical antenna are given different properties: the reflective material is applied selectively to specific sidewalls to control light reflection, while grating protrusions are formed on opposite sidewalls to enable diffraction. This local differentiation of properties allows the structure to achieve both broad field of view and controlled beam steering.
2Reliability
If conventional grating couplers are used, then manufacturing is straightforward, but optical leakage occurs and coupling efficiency is limited
Solution Approach 1:
Reflective material is introduced as an intermediary element between the waveguide core and the external environment. This reflective material confines optical modes within the waveguide by reflecting light that would otherwise leak, thereby improving signal fidelity while maintaining compatibility with standard fabrication processes.
Solution Approach 2:
The optical antenna employs composite material structures combining semiconductor waveguide material with deposited reflective materials (such as metal layers or dielectric mirrors). This composite approach enhances optical confinement and coupling efficiency while utilizing materials and processes compatible with existing semiconductor manufacturing techniques.
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 optical antenna design improves signal transmission by reducing optical leakage and increasing coupling efficiency, making it suitable for applications requiring a broader field of view, such as LiDAR and photonic phased arrays.
Implementation Method 1
a reflective material along the second sidewall of the vertically oriented semiconductor waveguide
Implementation Method 2
a first plurality of grating protrusions extending from the first sidewall of the vertically oriented semiconductor waveguide
Data Source
AI summary
Embodiments of the disclosure provide an optical antenna for a photonic integrated circuit (PIC). The optical antenna includes a vertically oriented semiconductor waveguide with a first end on a semiconductor layer. The vertically oriented semiconductor waveguide includes a first sidewall and a second sidewall opposite the first sidewall. A reflective material is along the second sidewall of the vertically oriented semiconductor waveguide. A first plurality of grating protrusions extends from the first sidewall of the vertically oriented semiconductor waveguide.