Miniaturized computational spectrometers are a powerful tool in many fields of research, from medicine to environmental monitoring. They can obtain incident spectra through a combination of device spectral responses and reconstruction algorithms, making them essential for on-chip and implantable applications. Highly sensitive spectral measurement using a single detector allows these spectrometers' footprints to be scaled down while achieving spectral resolution approaching that of benchtop systems.
The new era of digital spectrometers
Our approach is based on a van der Waals junction, a type of two-dimensional material heterostructure composed of two different materials stacked on top of each other. In this case, the junction was made from a layer of graphene and a layer of hexagonal boron nitride (hBN), both of which are known for their exceptional electronic and optical properties. By applying a voltage to the junction, our team were able to tune its spectral response, which allowed them to measure the incident light's spectrum.
The van der Waals junction was coupled to a photodetector, which converted the incident light into an electrical signal. The signal was then processed using a reconstruction algorithm that took into account the spectral response of the van der Waals junction and the photodetector's response. The result was a highly accurate and high-resolution spectrum of the incident light.
One of the most remarkable aspects of our team's approach is the high peak wavelength accuracy we achieved, which is around 0.36 nanometers. This level of accuracy is comparable to that of benchtop spectrometers, which are much larger and more expensive. Moreover, our approach offers a broad operation bandwidth, which makes it suitable for a wide range of applications.
We have also demonstrated proof-of-concept spectral imaging, in which we obtained spatially resolved spectra of a test sample. The sample consisted of a pattern of different colors, and the authors were able to obtain spectra from each color with high accuracy and resolution. This result shows the potential of our approach for use in imaging applications, such as for example microscopy and biomedical imaging.
Overall, our approach represents a significant advance in the field of miniaturized computational spectrometers. Our van der Waals junction-based approach offers unprecedented performance in terms of accuracy, resolution, and operation bandwidth for single-detector spectrometers, and it opens the door to ultraminiaturization of these devices. Our proof-of-concept spectral imaging also shows the potential of their approach for use in imaging applications.
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Stay tuned to see how this technology develops in the future and how it will impact various fields of our daily lives.
We are here to change how, why, when and where we use and make use of hyperspectal imaging in our daily lives, industrial processes and material recycling as well as security and military applications.