Coupled Microresonator Frequency Comb Tuning in Normal GVD

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Solution Overview

Problem

Existing frequency combs suffer from low power efficiency and limited tunability, particularly in the normal group velocity dispersion (GVD) regime.

Innovation Solution

The generation of an optical frequency comb is achieved through parametric four-wave mixing in a high-finesse microcavity, utilizing mode interactions between different spatial or polarization modes of coupled micro-resonators, allowing for control over the coupling strength and GVD to tune the comb bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If soliton-modelocked comb generation is used in anomalous GVD regime, then low-noise frequency comb can be generated, but the bandwidth is determined by material dispersion and is not readily tunable after fabrication

Engineering Contradiction:

Improvecomb stabilityVSAvoidcomb bandwidth tunability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent makes the comb bandwidth tunable by dynamically adjusting the coupling strength between resonators after fabrication. The coupling strength can be controlled by adjusting the distance between resonators or using Mach-Zehnder interferometers, enabling dynamic tuning of the number of comb lines from tens to hundreds without requiring device fabrication changes.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating regime from anomalous GVD to normal GVD and uses mode interactions between different spatial or polarization modes to generate combs. By controlling the coupling strength parameter, the bandwidth can be tuned while maintaining comb generation through parametric four-wave mixing processes.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If traditional frequency comb generation methods are used, then comb lines can be generated, but power conversion efficiency is low

Engineering Contradiction:

Improvecomb line generationVSAvoidpower conversion efficiency

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent combines multiple resonators with different modes (spatial or polarization modes) to enhance the nonlinear optical process of parametric four-wave mixing. This merging of modes enables high power conversion efficiency (>40%) by utilizing mode interactions that strengthen the comb generation process.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If mode interactions between spatial or polarization modes are used for comb generation, then comb formation can occur, but the interactions depend on intrinsic resonator properties and are typically not tunable

Engineering Contradiction:

Improvecomb formation capabilityVSAvoidcomb bandwidth control

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic control of the coupling strength between resonators, which directly controls the comb bandwidth. By adjusting the distance between resonators or using Mach-Zehnder interferometers, the system can be tuned to generate different numbers of comb lines (tens to hundreds) while maintaining mode interaction-based comb formation.

Inventive Principle:

Principle #15Dynamics

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 high power conversion efficiency (>40%) and flexible tuning of the comb bandwidth, allowing for the generation of tens to hundreds of comb lines, addressing the limitations of traditional soliton-modelocked combs.

Implementation Method 1

Comb generation can occur via parametic oscillation through a nonlinear optical process of parametric four-wave mixing (FWM) in a high-finesse microcavity

Methodology Applied

Scientific EffectParametric four-wave mixing:

Implementation Method 2

comb formation can be enabled through the use of a mode interaction between two different modes of the resonator

Methodology Applied

Scientific EffectMode interaction:

Implementation Method 3

The coupling strength between the two different cavities, along with the GVD of the micro-resonator can determine the bandwidth of the generated comb

Methodology Applied

Scientific EffectOptical coupling:

Implementation Method 4

This spectral tuning can be performed through thermal tuning of one or both of the micro-resonators. Thermal tuning may be performed using integrated heaters

Methodology Applied

Scientific EffectThermal tuning:

Implementation Method 5

Electrical tuning may be performed (e.g., by free-carriers) using a PIN junction in indirect bandgap materials, such as silicon, germanium

Methodology Applied

Scientific EffectFree-carrier effect:

Implementation Method 6

Electrical tuning may be performed using electro-optic materials, such as lithium niobate, lithium tantalate

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS12300963B2Tunable optical frequency comb generator in microresonators

Publication Date: 2025.05.13 THE TRUSTEES OF COLUMBIA UNIV IN THE CITY OF NEW YORK

AI summary

Optical frequency combs and related methods, devices, and systems are described. An example device can comprise a waveguide configured to optically couple to an optical source and at least one optical resonator optically coupled to the waveguide. The one or more of the at least one optical resonator can be tuned such that an optical frequency comb is generated based on mode interaction between two different modes of the at least one optical resonator. The device can comprise an output coupled to the waveguide and configured to output the optical frequency comb.