Pulsed Power Measurement Using Dual Receivers and Time Gating
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Solution Overview
Problem
Commercial optical power meters are inadequate for measuring high-speed, short-time optical pulses due to their long measurement times and reduced dynamic range caused by high noise floors, which is critical for evaluating the performance of switching devices and systems in optical communication and sensor applications.
Innovation Solution
A measurement apparatus and method that chops the signal in the time domain to prevent high power portions from reaching high sensitivity receivers, utilizing two separate receivers with different bandwidths and integration times to measure high-speed, high dynamic range pulsed signals, allowing for optimization of receivers for low-level signals and extending low noise measurement by leveraging the long cut-off duration of low duty cycle signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial optical power meters are used to measure low power levels, then measurement sensitivity is improved, but measurement time increases to hundreds of microseconds to milliseconds
Solution Approach 1:
The measurement system is segmented into two separate receivers: a high-speed receiver for measuring high power levels during pulse conduction, and a high-sensitivity receiver for measuring low power levels during pulse cut-off. This segmentation allows each receiver to be optimized for its specific measurement task, achieving both high speed and high sensitivity without compromise.
Solution Approach 2:
The system exploits the periodic nature of pulsed signals by measuring during specific phases: the high-speed receiver operates during the pulse conduction phase, while the high-sensitivity receiver operates during the pulse cut-off phase. This periodic measurement approach enables the system to achieve both fast response and high sensitivity by utilizing different time windows.
2Speed
If wideband/high speed photodiodes are used to measure high speed pulses, then measurement speed is improved, but dynamic range is substantially reduced due to high noise floor
Solution Approach 1:
The system segments the measurement function into two specialized receivers: a wideband high-speed photodiode for fast pulse measurement, and a high-sensitivity low-noise photodiode for extended dynamic range. Each receiver handles a specific portion of the measurement task, allowing both speed and dynamic range requirements to be satisfied simultaneously.
Solution Approach 2:
An optical modulator is introduced as an intermediary device to control the signal path. The modulator switches between directing the optical signal to the high-speed receiver or the high-sensitivity receiver based on the pulse phase, enabling the system to achieve both high speed and extended dynamic range measurements.
3Measurement precision
If signal is continuously transmitted to high sensitivity receiver, then low power measurement capability is improved, but high power portions cause saturation and measurement failure
Solution Approach 1:
An optical modulator serves as an intermediary device that selectively blocks or passes the optical signal based on the pulse phase. During pulse conduction, the modulator blocks the signal from reaching the high-sensitivity receiver, preventing saturation. During pulse cut-off, the modulator allows the signal to pass through, enabling low power measurement.
Solution Approach 2:
The system applies preliminary anti-action by using the optical modulator to preemptively block high power signal portions from reaching the high-sensitivity receiver before saturation can occur. This preventive measure protects the receiver and enables accurate low power measurement during the cut-off phase.
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 high dynamic range and high-speed power level measurements of pulsed signals in both conduction and cut-off states, even while systems are running, with the ability to construct detailed pulse power profiles, overcoming the limitations of commercial meters by reducing noise and increasing measurement speed.
Implementation Method 1
at least one power divider unit, alternately coupler connected to mentioned modulator-I's output and divides signals came from the modulator-I to parts as a low power part and a high power part
Implementation Method 2
at least one low pass filter-I which is connected with mentioned receiver-I for band limiting and anti-aliasing
Data Source
AI summary
A measurement method and apparatus for determining power levels of pulsed power signals, wherein the pulsed power signals are needed for some applications with a high dynamic range and a high speed simultaneously. The apparatus and the measurement method particularly used to evaluate a performance of fiber optic sensors, optical pulse generators, switching devices and debugging other pulsed power systems.