Multi-transverse-mode optical processor
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Solution Overview
Problem
Programmable optical processors face challenges in fabrication variations leading to computation errors and require complex hardware for sensing optical phase, limiting their reconfigurability and accuracy.
Innovation Solution
A multi-transverse-mode optical processor (MTMOP) design using a first and second Mach-Zehnder interferometer (MZI) with phase shifters that impart different phase shifts to optical modes, allowing phase calibration without coherent detection by measuring optical power changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ex-situ programming is used to implement weight matrices on optical processors, then reconfigurability is improved, but hardware complexity increases due to the need for optical phase sensing
Solution Approach 1:
The patent replaces complex optical phase sensing hardware with a simplified electrical measurement system. Instead of using coherent detection or complex optical phase meters, the invention uses electrical signals to measure optical power changes, substituting optical measurement mechanisms with electrical ones to reduce hardware complexity while maintaining programming capability
Solution Approach 2:
The patent introduces an intermediary conversion mechanism that transforms optical phase information into optical power variations, which are then converted to electrical signals for measurement. This intermediary approach allows phase sensing to be achieved through power measurement, avoiding direct complex optical phase detection hardware
2Ease of manufacture
If fabrication variations are present in silicon photonic processors, then manufacturing feasibility is improved, but computation accuracy deteriorates
Solution Approach 1:
The patent implements feedback mechanisms through in-situ training where the system measures actual optical output and adjusts phase shifters accordingly. This feedback loop compensates for fabrication variations by automatically tuning the device parameters to achieve desired computational accuracy despite manufacturing tolerances
Solution Approach 2:
The patent dynamically adjusts phase shifter parameters during operation to compensate for fixed fabrication variations. By changing operational parameters rather than relying solely on fixed manufacturing precision, the system maintains computation accuracy despite manufacturing tolerances
3Manufacturing precision
If in-situ training methods are used for programming optical processors, then computation accuracy is improved, but programming time increases
Solution Approach 1:
The patent performs preliminary measurements and characterizations during fabrication to establish baseline device parameters. This preliminary action reduces the time needed for subsequent in-situ training by providing initial guidance on phase shifter settings, thereby reducing overall programming time while maintaining accuracy
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
Enables accurate and efficient programming of optical processors by measuring phase shifts through optical power variations, reducing hardware complexity and improving reconfigurability.
Implementation Method 1
a first phase shifter optically coupled to the first internal waveguide arm of the first MZI and configured to impart a same first phase shift to the optical modes, a second phase shifter optically coupled to the first internal waveguide arm of the second MZI and configured to impart a same second phase shift to the optical modes and a third phase shifter optically coupled to the second internal waveguide arm of the second MZI and configured to impart a third phase shift to the optical modes
Implementation Method 2
a first Mach-Zehnder interferometer (MZI) and a second MZI optically coupled to the first MZI, each of the first MZI and the second MZI having a first internal waveguide arm and a second internal waveguide arm configured to propagate optical modes therein
Data Source
AI summary
There is provided an optical processing unit comprising a first Mach-Zehnder interferometer (MZI) and a second MZI optically coupled to the first MZI, each of the first MZI and the second MZI having a first internal waveguide arm and a second internal waveguide arm configured to propagate optical modes therein, a first phase shifter optically coupled to the first internal waveguide arm of the first MZI and configured to impart a same first phase shift to the optical modes, a second phase shifter optically coupled to the first internal waveguide arm of the second MZI and configured to impart a same second phase shift to the optical modes, and a third phase shifter optically coupled to the second internal waveguide arm of the second MZI and configured to impart a third phase shift to the different optical modes, the third phase shift having a different value for each of the optical modes.