Optical Spectrum Analyzer for Unknown Pulse-Modulated Light
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Solution Overview
Problem
Existing optical spectrum analyzers cannot measure the peak level of pulse-modulated light when the pulse-on time and pulse period are unknown, making it difficult to adjust sampling timing and measure peak levels accurately.
Innovation Solution
An optical spectrum analyzer that includes a diffraction grating, light receiving units, a measurement timing signal generation unit, and a peak hold circuit, which determines hold and sampling timings based on 0th-order light to sample and measure the peak of diffracted light of other orders, allowing for peak level measurement even when pulse-on time and pulse period are unknown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pulse-modulated light is used to suppress temperature changes, then wavelength and level stability are improved, but the ability to measure peak levels accurately deteriorates when pulse-on time and pulse period are unknown
Solution Approach 1:
The patent introduces 0th-order light as an intermediary signal to determine sampling timing. The 0th-order light receiving unit detects the pulse modulation timing information, and this information is used to generate sampling signals that synchronize with the pulse-modulated light. This intermediary approach allows accurate peak level measurement without needing to know the pulse-on time and pulse period in advance.
2Measurement precision
If sampling timing is adjusted based on known pulse parameters, then peak level measurement accuracy is improved, but the applicability to unknown pulse conditions deteriorates
Solution Approach 1:
The system uses the 0th-order light from the pulse-modulated light itself to determine sampling timing. The pulse modulation information embedded in the 0th-order light serves the dual purpose of indicating when the pulse is active and providing the timing reference for sampling. This self-service approach eliminates the need for external timing information or prior knowledge of pulse parameters.
3Measurement precision
If a spectroscopic analyzer is used to measure pulse-modulated light, then the ability to measure optical spectrum is improved, but the function of detecting pulse-on time and pulse period deteriorates
Solution Approach 1:
The patent divides the light detection into two separate functional paths: one path (0th-order light receiving unit) dedicated to detecting pulse timing information, and another path (diffracted light receiving unit) dedicated to spectral analysis. This segmentation allows each path to be optimized for its specific function while working together to provide comprehensive measurement capabilities.
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 measurement of peak levels for each wavelength of pulse-modulated light, even when the pulse-on time and pulse period are unknown, by generating appropriate sampling signals based on 0th-order light, ensuring precise peak detection and measurement.
Implementation Method 1
a diffraction grating (3) on which pulse-modulated light is incident
Implementation Method 2
a first light receiving unit (8) that receives 0th-order light of diffracted light diffracted by the diffraction grating (3), a second light receiving unit (7) that receives the diffracted light of an order other than the 0th-order light
Data Source
AI summary
Provided are an optical spectrum analyzer and a pulse-modulated light measurement method capable of measuring pulse-modulated light even when a pulse-on time and a pulse period of the pulse-modulated light are unknown. Pulse-modulated light (DUT) is incident on a diffraction grating 3. A first light receiving unit 8 receives the 0th-order light of diffracted light diffracted by the diffraction grating 3. A second light receiving unit 7 receives diffracted light of an order other than the 0th-order light. A measurement timing signal generation unit 9 generates a sampling signal based on the 0th-order light received by the first light receiving unit. The spectrum of the diffracted light received by the second light receiving unit is measured based on the sampling signal generated by the measurement timing signal generation unit.