4H Silicon Carbide Nonlinear Optical Device for High-Power Mid-Infrared Generation

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Solution Overview

Problem

Existing mid-infrared nonlinear optical crystals have low laser-induced damage thresholds, limiting their applications in generating high-power mid-infrared lasers, and there is a lack of accurate refractive index measurements in the infrared band for 6H silicon carbide crystals, leading to incorrect phase matching conditions for nonlinear optical frequency conversion.

Innovation Solution

A nonlinear optical device utilizing a 4H silicon carbide crystal with accurately measured refractive indices in both visible and infrared bands, achieving phase matching for nonlinear optical frequency conversion and enabling the production of high-power mid-infrared lasers through difference frequency generation, optical parametric amplification, and other processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If existing mid-infrared nonlinear optical crystals (LiNbO3, KTiOPO4, AgGaS2, ZnGeP2) are used, then relatively high nonlinear optical coefficients are achieved, but laser induced damage thresholds are very low

Engineering Contradiction:

Improvenonlinear optical coefficientVSAvoidlaser induced damage threshold

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent changes the material parameter from conventional nonlinear optical crystals to 4H silicon carbide crystal, which has fundamentally different physical properties. This material substitution maintains high nonlinear optical coefficients while providing extremely high laser induced damage thresholds, resolving the contradiction between power handling and reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs 4H silicon carbide as a composite crystal structure with specific polytype characteristics, combining the benefits of high nonlinear optical response with exceptional damage resistance. The unique crystal structure of 4H-SiC provides both the required nonlinear optical performance and superior mechanical strength

Inventive Principle:

Principle #40Composite materials

2Reliability

If 4H silicon carbide crystal is used for nonlinear optical frequency conversion, then high laser induced damage thresholds and broad transmissive bands are achieved, but accurate refractive index measurements in infrared band were previously unavailable leading to incorrect phase matching conditions

Engineering Contradiction:

Improvelaser induced damage thresholdVSAvoidrefractive index measurement precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary and accurate measurement of refractive indices of 4H silicon carbide crystal across the infrared spectrum before applying the material to nonlinear optical devices. This preliminary characterization work establishes correct phase matching conditions, preventing subsequent operational failures and ensuring optimal device performance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces conventional measurement methods with precision optical techniques to accurately determine refractive indices in the infrared band. This substitution of measurement methodology enables precise characterization of the 4H-SiC crystal properties, resolving the measurement precision issue

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

The 4H silicon carbide crystal device achieves efficient nonlinear optical frequency conversion in the mid-infrared band with high power and quality output, overcoming the limitations of existing crystals due to its high laser-induced damage threshold, broad transmissive band, and high thermal conductivity.

Implementation Method 1

nonlinear optical frequency conversion, such as optical parametric oscillation, optical parametric amplification, and difference frequency generation

Methodology Applied

Scientific EffectNonlinear optical frequency conversion: Second Harmonic Generation

Implementation Method 2

Relatively high transmittance in the visible and infrared spectra (specifically, 4H silicon carbide is transmissive in a range of 0.38-5.5 μm)

Methodology Applied

Scientific EffectLight transmission: Refraction

Implementation Method 3

High thermal conductivity (490 Wm−1K−1 for both 4H and 6H silicon carbide)

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9500931B2Nonlinear optical device manufactured with 4H silicon carbide crystal

Publication Date: 2016.11.22 BEIJING TIANKE HEDA SEMICON CO LTD

AI summary

Provided is a nonlinear optical device manufactured with 4H silicon carbide crystal. The nonlinear optical crystal may be configured to alter at least a light beam (12) at a frequency to generate at least a light beam (16) at a further frequency different from the frequency. The nonlinear optical crystal comprises a 4H silicon carbide crystal (13). The nonlinear optical device is more compatible with practical applications in terms of outputting mid-infrared laser at high power and high quality and thus are more applicable in practice, because the 4H silicon carbide crystal has a relatively high laser induced damage threshold, a relatively broad transmissive band (0.38-5.9 μm and 6.6-7.08 μm), a relatively great 2nd-order nonlinear optical coefficient (d15=6.7 pm/V), a relatively great birefringence, a high thermal conductivity (490 Wm−1K−1), and a high chemical stability.