Single-Channel Time-Domain Sampling Filter for Compact Spectrometers
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Solution Overview
Problem
Traditional spectrometers face challenges in miniaturization due to high energy loss, large size, high cost, and low signal-to-noise ratio, particularly in computational spectrometers with multiple spatial sampling channels, which limit their integration and detection efficiency.
Innovation Solution
An adjustable single-channel time-domain sampling filter using cascaded asymmetric interference units with phase modulators, allowing a single-channel structure that enhances integration, reduces spatial volume, and increases signal-to-noise ratio, while achieving high detection accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple independent sampling channels are constructed in the spatial domain, then spectral detection capability is improved, but device volume and resource consumption increase
Solution Approach 1:
The patent merges multiple spatial sampling channels into a single time-domain sampling channel by using a cascaded Mach-Zehnder interferometer structure with phase modulators. The system sequentially applies different phase modulation patterns to the same physical channel, enabling multiple spectral measurements to be performed through time-multiplexed phase control rather than requiring multiple parallel spatial channels. This reduces device volume while maintaining spectral detection capability.
Solution Approach 2:
The patent transitions from spatial domain multiplexing to time domain multiplexing. Instead of arranging multiple sampling channels side-by-side in space, the system uses temporal sequencing with phase modulators to create virtual multiple channels from a single physical channel. This dimensional transformation from space to time resolves the contradiction between detection capability and device size.
2Productivity
If incident spectrum power is evenly divided into multiple parts for multiple channels, then parallel detection is improved, but signal-to-noise ratio of each channel deteriorates
Solution Approach 1:
The patent ensures continuous full-power illumination of the single sampling channel by sequentially applying different phase modulation patterns rather than splitting power across multiple channels. The phase modulators dynamically reconfigure the interferometer transfer function during detection, allowing the same optical power to be fully utilized for each spectral measurement sequence, thereby maintaining high signal-to-noise ratio while achieving parallel detection capability through time-multiplexed phase control.
3Measurement precision
If traditional dispersive spectrometers use prisms or narrowband filters, then spectral resolution is improved, but energy loss and device size increase
Solution Approach 1:
The patent replaces traditional mechanical/optical dispersive elements (prisms, narrowband filters) with an integrated photonic circuit based Mach-Zehnder interferometer controlled by phase modulators. Instead of using physical dispersion mechanisms that inherently lose energy, the system uses electrical phase control to dynamically adjust the interferometer transfer function, achieving spectral resolution through interference patterns rather than physical separation. This substitution eliminates the energy loss associated with traditional dispersive components while maintaining compact integration.
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
The solution provides a compact, high-integration spectrometer with improved spectral power and signal-to-noise ratio, enabling fast and accurate spectral detection.
Implementation Method 1
a first waveguide splitting element, arranged at an input end, for splitting an input light into two paths for output according to a preset splitting ratio
Implementation Method 2
A second waveguide splitting element, for combining the output light of the two interference arms to induce optical interference
Implementation Method 3
at least three asymmetric interference units are provided with phase modulators on their interference arms
Data Source
AI summary
The provided is an adjustable single-channel time-domain sampling filter, a spectrometer, and a detection method. The filter includes N stages of cascaded asymmetric interference units, where each asymmetric interference unit includes: a first waveguide splitting element, arranged at the input end, for splitting input light into two output paths; two interference arms, which respectively receive the light output from the two paths of the first waveguide splitting element and have different arm lengths; and a second waveguide splitting element, for combining the output light of the two interference arms to generate optical interference. Among the N cascaded asymmetric interference units, at least three are provided with phase modulators on their interference arms. When in use, the adjustable single-channel time-domain sampling filter tunes the phase modulators located in different cascaded asymmetric interference units to form optical channels with different spectral responses in the time sequence.