Wavelength-Multiplexed Optical Signal Measurement via Temporal Sampling
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Solution Overview
Problem
Conventional methods for measuring signal amplitude in wavelength-multiplexed optical signals require precise wavelength separation and control, which is costly and challenging for dense wavelength intervals.
Innovation Solution
A measurement device and method that uses ultrafast sequentially sampled electrical field sampling and Fourier analysis to calculate the electrical field amplitude of each wavelength without wavelength separation, employing a light generating unit, splitting unit, delay unit, optical 90-degree hybrids, and computing unit to measure the total electrical field amplitude and determine the amplitude of each wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavelength separation is performed using a multilayer film optical filter or diffraction grating, then the amplitude of each wavelength can be measured, but the physical locations and temperatures of the elements need to be controlled with extremely high precision, resulting in high costs and management difficulties
Solution Approach 1:
The patent extracts the wavelength separation function from the physical measurement path. Instead of separating wavelengths spatially using filters or gratings, the invention extracts only the necessary information (total electrical field amplitude) through temporal sampling, then separates wavelengths mathematically via Fourier analysis. This eliminates the need for precision-controlled optical elements while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical/optical wavelength separation system (filters, gratings requiring precision control) with an electrical signal processing system. The optical field is converted to electrical domain through photodetection, and wavelength separation is achieved through digital Fourier transformation rather than physical separation, substituting mechanical precision requirements with computational processing.
2Measurement precision
If wavelength separation is performed with high precision control, then accurate wavelength measurement is achieved, but the costs and management complexity increase significantly
Solution Approach 1:
The invention substitutes expensive precision-controlled optical components with standard photodetectors and digital signal processing equipment. The wavelength separation function is transferred from the optical domain (requiring precision filters/gratings) to the electrical domain (using Fourier analysis), dramatically reducing manufacturing costs and simplifying system management while maintaining measurement accuracy.
Solution Approach 2:
The patent changes the domain parameter from spatial/optical separation to temporal/electrical sampling. By measuring the total electrical field amplitude at multiple time points and applying Fourier transformation, the system achieves wavelength separation without requiring precision-controlled optical parameters, thereby reducing manufacturing complexity and cost.
3Reliability
If conventional wavelength separation methods are used, then each wavelength signal can be extracted, but the system becomes complex and difficult to manage
Solution Approach 1:
The patent merges the wavelength separation function with the measurement function. Instead of using separate optical components for wavelength separation and then measuring each channel, the invention combines both functions into a single temporal sampling and Fourier analysis process. This integration simplifies the system architecture and reduces management complexity while maintaining reliable wavelength-specific measurements.
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 signal amplitude at each wavelength without the need for precise wavelength separation, effectively processing optical signals with dense wavelength intervals and reducing costs associated with high-precision control.
Implementation Method 1
M optical 90-degree hybrids that multiplex the sampling pulse light and the wavelength-multiplexed optical signal light and form signal light beams with phases separated 90 degrees from one another
Implementation Method 2
M balance light receivers that receive light beams emitted from the M optical 90-degree hybrids, and obtain orthogonal currents
Implementation Method 3
a sequentially sampled electrical field analyzing unit that applies Fourier analysis to the result of the measurement carried out by the sequentially sampled electrical field sampling unit, and calculates the electrical field amplitude of the signal component of each wavelength
Data Source
AI summary
Light to be measured L and sampling pulse light LSP are each split into M beams, and a time delay of 0, T, 2T, . . . , (M−1)T is given to each of the M-split sampling pulse light beams. The M-split light beams to be measured are then respectively multiplexed with M optical 90-degree hybrids, and M electrical field amplitudes per time T are determined for the light beam to be measured, based on M sets of output currents received at a balance light receiving element that receives light emitted from each of the optical 90-degree hybrids. The amplitudes of the respective wavelength optical signals contained in the light beam to be measured are calculated through Fourier transformations of the field electrical amplitudes. Pulsed light with a spectral width that covers the total frequency bandwidth of the light to be measured is used as the sampling pulse light. Where the total frequency bandwidth of the light to be measured is Δftotal, and the frequency interval of the optical signals contained in the light to be measured is Δf, T≦1/Δftotal and 1/(MT)≦Δf are set.