Wavelength Tunable Laser Module Interpolation Control
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Solution Overview
Problem
The existing wavelength tunable laser modules face challenges in accurately controlling laser wavelengths for flexible grid methods, particularly when the number of channels increases significantly, making calibration and control impractical due to the need for storing laser driving conditions and control target values for each channel.
Innovation Solution
A method and module that utilize a laser light source, a wavelength filter with a periodic transmission characteristic, and a controller to control the wavelength filter's transmission characteristic based on measured frequencies and control values, allowing for efficient selection and calculation of the appropriate control values for the closest basic frequency channel to achieve the desired wavelength, reducing the need for extensive calibration and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed on all channels to achieve high wavelength accuracy, then wavelength control precision is improved, but device complexity and storage requirements increase significantly
Solution Approach 1:
The patent segments the frequency spectrum into discrete basic frequency channels (e.g., 50 GHz spacing) and performs calibration only at these channel points. This segmentation allows the system to achieve wavelength accuracy for all channels by interpolating from the calibrated basic channels, thereby avoiding the need to calibrate every single frequency point while maintaining measurement precision.
Solution Approach 2:
The patent creates a universal calibration data structure that can serve multiple purposes: it provides wavelength accuracy for basic frequency channels directly and enables interpolation for intermediate frequencies. The calibration data stored in memory serves both as reference values for basic channels and as basis for calculating wavelengths at non-basic frequencies, reducing overall system complexity.
2Adaptability or versatility
If the number of frequency channels is increased to cover the whole C-band with 0.1 GHz spacing, then adaptability and wavelength coverage are improved, but storage requirements and processing time increase
Solution Approach 1:
The patent segments the continuous frequency spectrum into discrete basic frequency channels with larger spacing (e.g., 50 GHz). By calibrating only at these segmented points and using interpolation for intermediate frequencies, the system achieves wide wavelength coverage across the C-band while storing data for only approximately 100 basic channels instead of 50,000 individual frequency points.
Solution Approach 2:
The patent performs calibration at a partial set of frequency points (basic channels with 50 GHz spacing) rather than at all possible frequency points. This partial calibration approach is sufficient because the system can calculate wavelengths at intermediate frequencies through interpolation, thereby reducing storage requirements while maintaining adaptability for wide wavelength coverage.
3Measurement precision
If calibration data is stored for all frequency points to ensure wavelength accuracy, then measurement precision is improved, but loss of time in processing and retrieving data increases
Solution Approach 1:
The patent segments calibration data storage to only basic frequency channels with larger spacing (e.g., 50 GHz). This segmentation reduces the volume of stored calibration data from 50,000 points to approximately 100 points, significantly decreasing data retrieval and processing time while maintaining wavelength accuracy through interpolation calculations for intermediate frequencies.
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 approach enhances wavelength accuracy and reduces the complexity of controlling multiple channels, achieving approximately ±0.2 GHz accuracy compared to ±0.6 GHz in comparative examples, while minimizing power consumption and storage requirements.
Implementation Method 1
The wavelength filter has a periodic transmission characteristic with respect to a wavelength of light... The periodic wavelength transmission characteristic is shifted in a wavelength direction depending on the temperature of the wavelength filter
Data Source
AI summary
A method of controlling a wavelength of a wavelength tunable laser module includes: referring to data of measured frequencies and wavelength filter control values at two or more points for each basic frequency channel, the data being stored in a memory of a controller; selecting the basic frequency channel closest to a frequency of laser light that a laser light source is instructed to emit; calculating a first wavelength filter control value for providing the instructed frequency of laser light from the data of the measured frequencies allocated to the basic frequency channel closest to the instructed frequency and the wavelength filter control values; and controlling the transmission characteristic of a wavelength filter using the first wavelength filter control value.