On-Chip Tunable Laser Spectrometer for Continuous Fine Wavelength Sweeping
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Solution Overview
Problem
Existing spectrometers are not compact enough to be worn as a bracelet, have low spectral resolution, and lack continuous wavelength sweeping, which is essential for accurate non-invasive glucose measurement.
Innovation Solution
A spectrometer using a tunable on-chip laser with multiple resonator cavities and tunable filters for simultaneous coarse and fine measurements, enabling high spectral resolution and continuous wavelength tuning, while maintaining a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If narrow-band lasers or wide-band LED with optical filters are used to achieve wavelength sweeping, then spectral measurement capability is improved, but device size increases and wearable form factor is compromised
Solution Approach 1:
The patent combines multiple resonator cavities with different free spectral ranges into a single integrated system. The first resonator cavity (with larger FSR) and second resonator cavity (with smaller FSR) are merged to provide both wide wavelength coverage and fine spectral resolution, eliminating the need for separate laser sources or filter systems.
Solution Approach 2:
The resonator cavity system serves multiple functions: it provides wavelength sweeping through resonant modes, achieves spectral filtering, and enables both coarse and fine spectral measurements. This multi-functionality replaces what would traditionally require separate components (lasers, filters, detectors), reducing overall device size.
2Device complexity
If discrete wavelength tuning is used to reduce device complexity, then device simplicity is improved, but spectral resolution and measurement accuracy deteriorate
Solution Approach 1:
The patent enables continuous wavelength sweeping by exploiting the resonant modes of the cavities. Instead of discrete wavelength steps, the system provides continuous spectral coverage by tuning through the resonant modes, achieving smooth wavelength variation essential for high-resolution spectroscopy.
Solution Approach 2:
The system dynamically switches between coarse scanning (using the first resonator with larger FSR) and fine scanning (using the second resonator with smaller FSR). This dynamic operation allows the device to adapt its resolution and scanning speed based on measurement requirements, maintaining high spectral resolution while managing device complexity.
3Measurement precision
If multiple LED sources are used to increase spectral resolution, then measurement accuracy is improved, but device size and power consumption increase
Solution Approach 1:
The patent merges the functions of multiple LED sources into a single tunable laser system based on resonator cavities. Instead of requiring multiple independent light sources to cover different wavelengths, the resonator system generates multiple wavelengths through its resonant modes, significantly reducing power consumption and device size.
4Device complexity
If fixed-step wavelength tuning is used to simplify control, then device complexity is reduced, but continuous spectral scanning capability is lost
Solution Approach 1:
The control system dynamically adjusts the operating mode between coarse and fine scanning based on measurement requirements. The system can switch between different resonator cavities and tuning steps, providing adaptability for both rapid overview scanning and detailed spectral analysis, thus maintaining versatility while managing control complexity.
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 high spectral resolution, continuous wavelength sweeping, and low energy consumption, allowing for accurate and efficient bio-information measurement, including non-invasive glucose detection.
Implementation Method 1
Each of the plurality of resonator cavities may include a waveguide and a plurality of tunable filters to generate lights having different wavelengths in accordance with parameters of the plurality of tunable filters of each of the plurality of resonator cavities
Implementation Method 2
a photodetector configured to receive the laser radiation reflected from the biological tissue
Data Source
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.