Offset Optical Frequency Comb RF Synthesizer for Wide Tunability
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Solution Overview
Problem
Existing microwave oscillators, despite their low phase noise, are too large for many systems where size is a concern, and miniature oscillator architectures using optical frequency combs are limited by fixed RF frequencies corresponding to the free spectral range of the resonator.
Innovation Solution
A tunable RF synthesizer based on offset optical frequency combs is developed, utilizing at least two lasers, a coupler, a resonator with a splitter, and a controller to split the resonant frequencies and generate highly tunable optical frequency combs, which are then converted into a tunable RF signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microwave oscillators are used to provide RF signals, then low phase noise is achieved, but the system size becomes prohibitively large
Solution Approach 1:
The patent replaces traditional microwave mechanical oscillators with an optical-based frequency comb system. The optical resonator generates frequency combs that are converted to RF signals through optical-to-electrical conversion, eliminating the need for large microwave oscillator hardware while maintaining low phase noise performance through the high Q-factor of optical resonators.
Solution Approach 2:
The patent changes the operating domain from microwave frequencies to optical frequencies for the resonator operation. By using optical frequencies (higher than microwave frequencies) to generate the frequency combs, the system achieves better phase noise performance in a compact form factor, then converts the optical frequency combs down to the desired RF range.
2Area of stationary object
If miniature oscillator architectures using optical frequency combs are used, then system size is reduced, but RF frequency becomes fixed at the free spectral range of the resonator
Solution Approach 1:
The patent introduces dynamic control of the optical resonator's resonant frequencies through a tunable element (such as a thermally-tuned microring resonator or electro-optic modulator). This allows the frequency combs to be dynamically adjusted across a wide range, enabling the RF output frequency to be tuned from 1 GHz to 40 GHz while maintaining the compact optical resonator architecture.
Solution Approach 2:
The patent uses multiple optical frequency combs generated by splitting the optical resonator into different coupling sections. Each section generates frequency combs at different offsets, and by combining or selecting from these multiple combs, the system achieves wide RF frequency tunability while maintaining a compact form factor.
3Adaptability or versatility
If offset optical frequency combs are generated using multiple lasers and a splitter, then RF frequency tunability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple optical functions into a single integrated photonic chip. The frequency comb generator, splitter, tunable elements, and optical-to-electrical converter are integrated onto one chip, reducing the physical footprint and inter-component connections while maintaining the functionality of generating tunable offset frequency combs for wide RF frequency coverage.
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 system achieves highly tunable RF signals with low phase noise, capable of frequencies from 1 GHz to 40 GHz, while maintaining a compact form factor, equivalent to that of larger oscillators.
Implementation Method 1
a resonator having a first section and a second section... to generate optical frequency combs associated with different resonant frequencies of each of the different optical paths
Implementation Method 2
a splitter that couples the first section to the second section, wherein the splitter splits a first proportion of the first laser output and a second proportion of the second laser output onto different optical paths within the resonator
Implementation Method 3
a controller that controls the splitter to change a size of the first proportion in relation to the first laser and the second proportion in relation to the second laser
Data Source
AI summary
Systems and methods for a tunable RF synthesizer based on offset optical frequency combs is provided herein. An exemplary system includes two lasers, a first laser generating a first laser output and a second laser generating a second laser output; and a coupler that receives the first and second laser outputs. Further, the system includes a resonator having first and second sections coupled to one another, the coupler coupling the first and second laser outputs into the resonator; a splitter that couples the first section to the second section, the splitter splitting a first proportion of the first laser output and a second proportion of the second laser output onto different paths within the resonator; and a controller that controls the splitter to change a size of the first proportion in relation to the first laser and the second proportion in relation to the second laser.