Wavelength Variable Light Source Thermal Drift Control
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Solution Overview
Problem
Current wavelength variable light source systems face challenges in maintaining accurate and stable wavelength and intensity settings due to influences from thermal value and scattering light, which degrades the output characteristics.
Innovation Solution
The system incorporates a DFB laser, SOA, and a control circuit with PID control loops for automatic current and temperature control, along with an ambient temperature dependency suppressing circuit to stabilize wavelength and intensity by monitoring and adjusting driving current, temperature, and light intensity using multiple photodiodes and thermoelectric coolers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wavelength variable light source systems are used, then basic wavelength control is achieved, but accuracy and stability of wavelength and intensity settings are degraded due to thermal value and scattering light influences
Solution Approach 1:
The patent implements multiple feedback control loops: a wavelength control loop that monitors output wavelength and adjusts the laser diode current and TEC temperature to maintain accurate wavelength settings, and an intensity control loop that monitors output intensity and adjusts the laser diode current to maintain stable intensity. These feedback mechanisms continuously counteract the effects of thermal drift and scattering light influences, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent dynamically adjusts operating parameters (laser diode current and TEC temperature) to compensate for environmental changes and internal drift. By continuously monitoring wavelength and intensity outputs and modifying these parameters in real-time, the system maintains accurate wavelength control and stable output characteristics despite thermal and scattering effects.
2Measurement precision
If simple temperature control is implemented, then basic stability is achieved, but accuracy of wavelength control is insufficient due to thermal drift
Solution Approach 1:
The wavelength control loop continuously monitors the actual output wavelength and compares it to the target wavelength. Based on this comparison, the system adjusts the laser diode current and TEC temperature to eliminate wavelength errors caused by thermal drift. This closed-loop feedback mechanism ensures accurate wavelength setting despite temperature variations.
Solution Approach 2:
The system performs preliminary wavelength calibration and stores calibration data for different temperature conditions. Before operation, the system characterizes the wavelength-temperature relationship and uses this pre-acquired information to predict and compensate for thermal drift, improving wavelength accuracy without requiring continuous complex adjustments.
3Adaptability or versatility
If intensity control is added to wavelength control, then comprehensive control capability is achieved, but system complexity increases
Solution Approach 1:
The patent combines wavelength control and intensity control into a unified control system that shares common components (laser diode current control, TEC control, monitoring photodiodes, and central processing unit). By merging these functions into a single integrated architecture rather than separate independent systems, the patent achieves comprehensive control capability while minimizing the increase in system complexity.
Solution Approach 2:
The control system is designed with multi-functionality, where the same hardware components (photodiodes, current control circuitry, temperature control circuitry) serve dual purposes for both wavelength control and intensity control. This universal approach allows the system to perform multiple control functions without proportionally increasing complexity.
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 configuration enhances the accuracy and stability of wavelength and intensity control, effectively suppressing the impact of thermal and scattering effects, ensuring precise and reliable optical output.
Implementation Method 1
a thermoelectric cooler (TEC) 216 for controlling the temperature of the semiconductor laser 215
Implementation Method 2
a photo diode (PD) 220 that detects the transmitted light
Data Source
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AI summary
There is provided a wavelength variable light source system (1) capable of changing wavelength and intensity of output signal light and of improving preset accuracy and stability of the wavelength and strength of the output signal light. The system (1) determines the both or either one of a target value for controlling wavelength and a target value for controlling intensity of output signal light of a wavelength variable light source (2) by correlating a combination of the target wavelength and the target light output intensity specified from a higher-level device and controls operation states of the wavelength variable light source (2) so that output values of monitoring circuits (18,21-1,21-2,22,24,26) for monitoring the operation state of the wavelength variable light source (2) converge to the target values.