On-Chip Opto-Digital Wavelength Meter With Parallel Quantization
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Solution Overview
Problem
Existing on-chip wavelength meters face challenges in implementing accurate and efficient measurements due to bulky components and complex signal processing, making it difficult to calibrate and control integrated tunable lasers effectively.
Innovation Solution
An integrated circuit with a set of interferometers, including Mach-Zehnder interferometers or ring resonators, provides digital electrical signals specifying the wavelength range from MSB to LSB, eliminating the need for analog-to-digital converters and signal processing, and utilizing a parallel implementation of binary quantization for precise wavelength measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing wavelength meters use bulk or free-space optics with multiple bulky components, then measurement accuracy can be achieved, but device size and complexity increase significantly
Solution Approach 1:
The patent integrates multiple interferometer functions into a single integrated circuit platform, combining what were previously separate bulk optical components into one compact device. This merging approach maintains measurement accuracy while dramatically reducing device complexity and size.
Solution Approach 2:
The invention replaces mechanical bulk optical components with integrated photonic circuit elements. By substituting free-space optics with waveguide-based interferometers on a chip, the system achieves the same measurement functionality with reduced complexity and improved stability.
2Measurement precision
If existing wavelength meters implement complicated signal processing with microprocessors, then wavelength measurement can be performed, but processing time and computational complexity increase
Solution Approach 1:
The patent extracts and eliminates the microprocessor and complicated signal processing components from the wavelength measurement system. By using direct digital detection methods, the invention removes the time-consuming computational steps while preserving measurement accuracy.
Solution Approach 2:
The interferometer outputs directly provide digital signals that can be immediately processed without requiring external microprocessor intervention. The system is designed to be self-sufficient, generating measurement results through direct detection rather than requiring separate processing stages.
3Measurement precision
If existing wavelength meters use scanning Michelson interferometer with microprocessor control, then wavelength measurement is achieved, but measurement speed and repetition rate are limited
Solution Approach 1:
The patent employs multiple interferometers operating in parallel, each providing periodic interference patterns at different frequencies. This parallel periodic operation enables simultaneous measurement of multiple wavelength components, dramatically increasing measurement repetition rate compared to sequential scanning methods.
Solution Approach 2:
The invention segments the measurement function across multiple interferometers with different path length differences. Each interferometer segment measures a specific wavelength range or provides a specific bit of the wavelength measurement, allowing parallel operation and faster overall measurement speed.
4Volume of moving object
If on-chip integration is implemented to reduce size and cost, then device compactness improves, but implementation and calibration difficulty increase
Solution Approach 1:
The patent designs the integrated interferometers with specific path length differences that create distinct, easily distinguishable interference patterns. By carefully selecting operational parameters such as path length differences and operating wavelengths, the system achieves both compact integration and simplified calibration through characteristic measurement signatures.
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 an accurate, compact, and efficient on-chip wavelength meter that operates at high speed, improving measurement accuracy and reducing complexity, suitable for controlling high-speed modulated lasers and immune to beam profile changes.
Implementation Method 1
light from a single light source may be split into two (or more) beams that travel in different optical paths, which are then combined again. The resulting interference may provide information about the wavelength of the light source
Implementation Method 2
one or more photodetectors, optically coupled to the set of interferometers, that provide analog electrical signals corresponding to the outputs
Data Source
AI summary
An integrated circuit that includes a wavelength meter is described. This integrated circuit may include: a set of interferometers having integer multiples of a phase or a delay, where the set of interferometers provide outputs corresponding to a range from an MSB to an LSB of a wavelength in an optical signal. For example, the set of interferometers may include MZIs or ring resonators. Moreover, the integrated circuit may include a converter that provides digital electrical signals that specify the range from the MSB to the LSB. Note that the set of interferometers may have different FSRs, where an interferometer that provides an output corresponding to the MSB has a largest FSR and a smallest phase or delay, and a second interferometer that provides a second output corresponding to the LSB has a smallest FSR and a largest phase or delay.