Optical Spectrum Analyzer for Pulsed Light Without Sweep Slowdown
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Solution Overview
Problem
Existing optical spectrum analyzers face challenges in stabilizing the measurement of pulsed light spectra while maintaining sweep speed due to the need for synchronizing pulsed light periods with A/D conversion sampling and limited sweep speeds by pulsed light frequency.
Innovation Solution
The optical spectrum analyzer employs a configuration with multiple amplifiers and A/D converters, allowing selection of unsaturated amplifiers based on digital values, and performs sampling at a time shorter than the pulsed light period, using an average or peak value of multiple sampled optical power signals to stabilize measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization between pulsed light period and A/D conversion sampling is implemented, then measurement stability is improved, but system complexity increases and sweep speed decreases
Solution Approach 1:
The patent divides the amplification function into multiple parallel amplifiers with different gain values. Each amplifier processes the optical power signal independently, and the A/D conversion unit selects outputs from different amplifiers based on saturation status. This segmentation eliminates the need for complex synchronization control while ensuring stable measurement of pulsed light spectra.
2Reliability
If synchronization between pulsed light period and A/D conversion sampling is implemented, then measurement stability is improved, but sweep speed decreases
Solution Approach 1:
The patent enables continuous sampling of the optical power signal by multiple A/D converters operating in parallel without interruption for synchronization. The useful action of sampling continues uninterrupted while the system selects appropriate signals from different amplifiers, thereby maintaining high sweep speed while ensuring measurement stability through multiple sampling opportunities.
3Measurement precision
If multiple amplifiers with different gains are used, then sampling success rate is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic selection of amplifier outputs based on real-time saturation detection. The control unit monitors the digital values from multiple A/D converters and dynamically selects the unsaturated signal for final measurement. This dynamic adaptation allows the system to handle varying optical power levels effectively while keeping the amplifier configuration relatively simple with only gain variations.
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 enables stable measurement of pulsed light spectra without reducing sweep speed by increasing the likelihood of sampling at peak timings and minimizing unsynchronized sampling periods.
Implementation Method 1
a diffraction grating 4 that emits diffracted light obtained by spectrally separating a wavelength included in pulsed light to be measured in a direction corresponding to the wavelength
Implementation Method 2
a light receiving section 8 that receives the diffracted light emitted from the spectral section 4 and converts the diffracted light into an electric signal
Data Source
AI summary
Provided is an optical spectrum analyzer capable of stably measuring a spectrum of pulsed light while suppressing a decrease in a sweep speed. An A/D conversion unit 17 has a plurality of inputs to which the outputs of a plurality of amplifiers Amp21 to Amp2m are connected. A control unit 12 selects one of the plurality of amplifiers Amp21 to Amp2m whose output is not saturated based on optical power signals amplified by the plurality of amplifiers Amp21 to Amp2m. The control unit 12 sets an average value of the optical power signals sampled by the A/D conversion unit 17 and amplified by the selected one of the amplifiers Amp21 to Amp2m as the optical power signal of the next wavelength, while sweeping from the previous wavelength to the next wavelength is performed.