Chip-Based Frequency Comb Generator With Disk Resonator
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Solution Overview
Problem
Existing chip-based frequency comb generators face challenges in achieving low repetition rates below 86 GHz while maintaining low turn-on threshold power, as reducing free-spectral-range (FSR) increases the turn-on threshold power, and high optical Q factors are necessary for efficient operation but difficult to achieve simultaneously.
Innovation Solution
A chip-based frequency comb generator using a silicon dioxide waveguide in a wedge structure disk resonator with a diameter ranging from 25 mm to 3 mm, allowing for low-threshold microwave to millimeter wave repetition rate control and achieving repetition rates from 2.6 GHz to 220 GHz with a pump power threshold as low as 1 mW, by optimizing the optical Q factor and surface-loss-limited behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the free-spectral-range (FSR) is reduced to achieve low repetition rates below 86 GHz, then the repetition rate is improved for direct detection, but the turn-on threshold power increases significantly
Solution Approach 1:
The patent changes the physical parameters of the resonator by optimizing the optical Q factor and adjusting the resonator geometry (disk diameter from 25 mm to 3 mm) to achieve low repetition rates while maintaining low turn-on threshold power. This allows operation across microwave to millimeter wave ranges with minimal power degradation
Solution Approach 2:
The patent enables dynamic control of repetition rates by varying the disk resonator diameter, allowing the system to adapt between 2.6 GHz and 220 GHz operation. This dynamic parameter adjustment resolves the contradiction by providing flexibility to optimize for either direct detection (lower rates) or other applications (higher rates)
2Power
If the optical Q factor is increased to reduce turn-on threshold power, then the power efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical or external Q-factor enhancement mechanisms with an integrated silicon dioxide waveguide wedge structure that inherently provides the necessary optical confinement and low loss. This substitution achieves high Q factors through material and geometric design rather than additional complex components
Solution Approach 2:
The patent uses composite material structures, specifically silicon dioxide waveguides integrated with disk resonators, to achieve both high optical Q factors and low turn-on threshold power. The combination of materials provides the necessary optical properties without requiring separate complex systems
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 solution enables a wide range of repetition rates from 2.6 GHz to 220 GHz with minimal degradation in turn-on power, allowing for direct detection of comb beat signals and efficient operation across the microwave to millimeter wave range, while providing cost benefits and integration with other optical components.
Implementation Method 1
A chip-based frequency comb generator using a silicon dioxide waveguide in a wedge structure disk resonator
Implementation Method 2
n2 (n) is the nonlinear index (refractive index)
Implementation Method 3
Higher Q creates larger resonant build-up so that a given coupled power creates a greater Kerr nonlinear coupling of signal and idler waves
Implementation Method 4
the optical Q factor has a significant impact upon exerts turn-on threshold power. Higher Q creates larger resonant build-up
Data Source
AI summary
A frequency comb generator fabricated on a chip with elimination of a disadvantageous reflow process, includes an ultra-high Q disk resonator having a waveguide that is a part of a wedge structure fabricated from a silicon dioxide layer of the chip. The disk resonator allows generation of a frequency comb with a mode spacing as low as 2.6 GHz and up to 220 GHz. A surface-loss-limited behavior of the disk resonator decouples a strong dependence of pumping threshold on repetition rate.