Silicon-Rich Nitride Electro-Optical Modulators for CMOS Beam Steering

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Solution Overview

Problem

Current optical devices with nonlinear optical materials are not compatible with silicon processing for CMOS circuits, leading to limitations in fabricating compact, reliable, and cost-effective optical modulators and beam steering systems, particularly for applications like LIDAR, due to high RF permittivity and low refractive indices relative to silicon.

Innovation Solution

The development of optical devices using silicon-rich nitride (SRN) materials formed over a silicon-based semiconductor substrate, incorporating a nonlinear optical material structure with a semiconductor cylindrical core and an external metal layer for electrical control, enabling phase shifting via refractive index control and metal-dielectric surface plasmon effects, allowing for compact, high-performance beam steering without mechanical components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional nonlinear optical materials (lithium-niobate, barium titanate) are used, then optical modulation functionality is achieved, but compatibility with silicon processing for CMOS circuits is lost

Engineering Contradiction:

ImproveCMOS compatibilityVSAvoidmaterial property suitability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent modifies the refractive index and RF permittivity parameters of the nonlinear optical material by using silicon-rich nitride instead of conventional materials, enabling CMOS compatibility while maintaining optical modulation functionality. The material composition is adjusted to achieve the desired optical and electrical properties that bridge the gap between conventional nonlinear materials and silicon processing requirements.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure combining silicon-rich nitride nonlinear optical material with silicon-based substrates and metal electrodes. This composite approach integrates the nonlinear optical properties needed for modulation with the mechanical and electrical properties of silicon and metal, achieving both CMOS compatibility and functional performance.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If conventional nonlinear optical materials with low refractive indices are used, then optical modulation is enabled, but device compactness and integration density are reduced

Engineering Contradiction:

Improveintegration densityVSAvoidrefractive index

Core Design Contradiction:

Device complexityVSShape

Solution Approach 1:

The patent increases the refractive index parameter of the nonlinear optical material by using silicon-rich nitride, which has a higher refractive index than conventional materials like lithium-niobate. This parameter change enables smaller device dimensions and higher integration density while maintaining the optical modulation functionality.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If mechanical components are used for beam steering, then steering functionality is achieved, but device reliability is reduced and device cost increases

Engineering Contradiction:

Improvedevice reliabilityVSAvoidbeam steering functionality

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces mechanical beam steering components with an electro-optical modulation system using silicon-rich nitride nonlinear optical material. Electrical signals control the optical properties of the material to achieve beam steering functionality without moving parts, thereby improving reliability and reducing cost while maintaining the essential steering capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables the creation of compact, high-performance optical beam steering systems with reduced mechanical components and lower costs, achieving effective phase shifts and efficient light modulation suitable for LIDAR applications, while being compatible with CMOS circuit fabrication.

Implementation Method 1

utilizing a Kerr effect-based nonlinear optical material

Methodology Applied

Scientific EffectKerr effect: Kerr Effect

Implementation Method 2

metal-dielectric surface plasmon effects

Methodology Applied

Scientific EffectSurface plasmon:

Data Source

PatentUS20230168561A1Electro-optical modulators and applications based on silicon processing compatible nonlinear optical materials

Publication Date: 2023.06.01 RGT UNIV OF CALIFORNIA

AI summary

The technology disclosed in this patent document for optical devices for modulating light using nonlinear optical materials exhibiting electro-optical effects. Suitable nonlinear optical materials can be formed over a silicon-based semiconductor substrate via a silicon processing compatible process. In one application, such a device can be implemented for steering light based on a unique two-dimensional array of phased optical modulators using integrated photonic chip fabrication technologies to provide high performance and small footprint device packaging. The phased optical modulators can be phase shifting elements, each of which can be configured as a vertical-cavity surface-emitting phase shifter (VCSEP) to provide effective phase changes via both the control of the optical refractive index of the nonlinear optical material and the metal-dielectric surface plasmon effect.