Planar Photonic Waveguide Pulse Rate Multiplier
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Solution Overview
Problem
Current optical pulse rate multipliers, particularly those based on optical fibers, are limited in increasing pulse repetition rate beyond 2-3 GHz due to practical constraints in fabricating short fibers for higher frequencies, leading to undesirable attenuation and phase noise issues, which are inadequate for applications requiring mid-repetition rates (10 GHz-30 GHz) in astronomy and exoplanet detection.
Innovation Solution
The development of a planar photonic waveguide optical pulse rate multiplier using a photonic integrated circuit (PIC) with cascading Mach-Zehnder interferometers (MZIs) that precisely control branch lengths to multiply pulse repetition rates up to several GHz with minimal power loss, employing monolithic optical waveguides and feedback servos for active control, enabling higher frequency stability and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If optical fibers are used for pulse rate multiplication, then flexibility and ease of manufacture are improved, but pulse repetition rate is limited to 2-3 GHz due to attenuation and phase noise
Solution Approach 1:
The patent replaces the mechanical/optical fiber-based pulse rate multiplication system with an integrated photonic circuit system. The PIC uses on-chip waveguides and Mach-Zehnder interferometers to achieve pulse rate multiplication, eliminating the limitations of optical fiber attenuation and phase noise while maintaining manufacturing feasibility through standard photonic fabrication processes.
Solution Approach 2:
The patent transitions from one-dimensional optical fiber propagation to two-dimensional planar photonic circuit routing. The PIC layout allows precise control of light paths through planar waveguides, enabling accurate timing control for pulse rate multiplication up to 30 GHz without the attenuation issues inherent in optical fiber implementations.
2Adaptability or versatility
If optical fibers are used for pulse rate multiplication, then flexibility is improved, but power loss and phase noise increase at higher frequencies
Solution Approach 1:
The patent substitutes optical fiber transmission with integrated photonic circuit waveguides. The on-chip waveguide structure minimizes propagation losses and eliminates the phase noise issues associated with optical fiber implementations, while maintaining the flexibility needed for mid-repetition rate applications through integrated circuit design.
3Measurement precision
If Fabry-Perot cavities are used to filter comb lines, then mode spacing precision is improved, but optical power is lost and expensive components are damaged
Solution Approach 1:
The patent extracts the pulse rate multiplication function from the frequency comb generation process itself. By using a PIC-based multiplier that operates on the comb output, the system achieves the required 10-30 GHz mode spacing without needing to filter out comb lines through Fabry-Perot cavities, thereby eliminating optical power loss and protecting expensive components.
Solution Approach 2:
The patent performs pulse rate multiplication as a preliminary step before the comb light reaches sensitive components. The PIC multiplier processes the comb output to achieve the desired repetition rate, preventing the need for subsequent filtering that would cause power loss and component damage.
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 solution effectively increases pulse repetition rates to tens or hundreds of GHz with minimal power loss and phase noise, providing stable and robust calibration sources for astronomical spectrographs and exoplanet detection, overcoming the limitations of fiber-based multipliers by utilizing precise fabrication of planar photonic components.
Implementation Method 1
cascading Mach-Zehnder interferometers (MZIs) that precisely control branch lengths to multiply pulse repetition rates
Data Source
AI summary
Disclosed herein is a pulse repetition rate multiplier including a photonic integrated circuit (PIC) including cascading Mach-Zehnder interferometers (MZIs). An input may be connected to one end of the PIC and an output may be connected to the other end of the PIC such that a signal from the input runs through the cascading MZIs and out the output. The input may be configured to receive an input pulsed signal and the output may be configured to output a repetition rate multiplied signal. Advantageously, using a PIC as opposed to an optical fiber-based pulse rate multiplier allows for accurate fabrication of a pulse repetition rate multiplier configured to accept higher frequency pulsed signals.