On-Chip Tunable Laser Spectrometer for Continuous High-Resolution Scanning
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Solution Overview
Problem
Existing spectrometers are not compact enough to be worn as a bracelet, have low spectral resolution, and perform discrete wavelength sweeping, which limits their ability to accurately measure parameters like blood glucose levels.
Innovation Solution
A spectrometer using a tunable on-chip laser with multiple resonator cavities and tunable filters for continuous wavelength sweeping, enabling high spectral resolution and simultaneous coarse and fine measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If narrow bandwidth tunable light sources or wideband light sources with optical filters are used, then spectral resolution is improved, but device size increases and wearable form factor is not achieved
Solution Approach 1:
The patent combines multiple resonator cavities with different free spectral ranges into a single integrated system on a chip. The first resonator cavity (with larger FSR) and second resonator cavity (with smaller FSR) are merged to provide both wide tuning range and high spectral resolution simultaneously, eliminating the need for separate light sources and filter systems.
Solution Approach 2:
The patent transitions from discrete wavelength points to continuous wavelength sweeping by introducing time-dependent tuning of the resonator cavities. The control unit continuously adjusts the resonant frequencies of both cavities over time, enabling smooth wavelength sweeping across the measurement range rather than discrete step-wise transitions.
2Device complexity
If discrete wavelength tuning is used, then device complexity is reduced, but measurement accuracy decreases due to inability to perform continuous spectral scanning
Solution Approach 1:
The patent implements continuous wavelength sweeping by continuously tuning the resonator cavities over time. The control unit adjusts the resonant frequencies of both cavities in a coordinated manner, ensuring uninterrupted spectral scanning. This continuous action enables accurate measurement of spectral features that would be missed with discrete tuning steps.
Solution Approach 2:
The patent introduces dynamic tuning capability where the resonator cavity parameters are continuously adjusted during measurement. The control unit modifies the resonant frequencies of both cavities in real-time, enabling the system to adapt and sweep through the entire spectral range continuously rather than switching between fixed wavelengths.
3Measurement precision
If multiple separate light sources are used to achieve high spectral resolution, then spectral resolution is improved, but energy consumption increases
Solution Approach 1:
The patent makes a single laser source multi-functional by using it to generate multiple wavelengths through the resonator cavity system. The first and second resonator cavities extract different wavelength ranges from the same laser source, enabling the single source to perform the work of multiple separate light sources while consuming less energy.
Solution Approach 2:
The patent segments the spectral output of a single laser source using multiple resonator cavities with different free spectral ranges. The first resonator cavity handles the broader wavelength range while the second resonator cavity provides fine spectral resolution in specific regions, allowing one laser to cover the functionality of multiple lasers across different wavelength bands.
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 spectrometer achieves compactness for wearable use, high spectral resolution, and continuous wavelength tuning with low energy consumption, providing accurate bio-information measurement.
Implementation Method 1
a laser source (2) configured to irradiate a biological tissue (3) with laser radiation
Implementation Method 2
Each of the plurality of resonator cavities (10A, 10B, and 10N) may include a waveguide (12) and a tunable filter (14A, 14B, and 14N)
Implementation Method 3
a photodetector (4) configured to receive the laser radiation reflected from the biological tissue (3)
Implementation Method 4
Each of the plurality of resonator cavities (10A, 10B, and 10N) may include a waveguide (12) and a tunable filter (14A, 14B, and 14N) to generate lights having different wavelengths
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A spectrometer may include: a tunable on-chip laser source configured to irradiate a biological tissue with laser radiation; a photodetector configured to receive the laser radiation reflected from the biological tissue; and at least one processor. The tunable on-chip laser source may include: a semiconductor gain chip having a gain bandwidth for operating the tunable on-chip laser source in a predetermined wavelength range; and a plurality of resonator cavities connected between the semiconductor gain chip and the at least one processor, and configured to perform a coarse high-speed measurement and a fine measurement to measure a spectrum of the laser radiation reflected from the biological tissue.