An ~1.5 pm resolution can be achieved with a snapshot measurement. The spectrometer can operate within 0.3-1 mm region. However, researchers from Zhejiang University managed to utilize the leaky mode by studying the induced random speckles to recover the hidden spectral information, while engineering the drawing conditions of the taper to maximize the leaky modes generation within a 1 mm taper region. If a microfiber taper is drawn under non-adiabatic conditions, coupling between different mode induced by the fiber geometry will generate leaky modes that are typically undesired for microfiber applications. Experiments usually use microfibers for confining light inside the fiber to propagate as long as possible. On the other hand, microfibers are ideal tools for manipulating light fields of their tailorable dispersion and small footprint. These usually require additional bulky or expensive equipment, such as a high-performance camera or even a microscope, to complete the measurement. However, most spectrometer designs based on it rely on random mediums such as rough surfaces, multimode fiber, integrating spheres, or photonic crystals. Multimode interferences could generate random speckles which are associated with spectra information. It could be used over long intervals while maintaining accuracy and reliability. In addition, this tiny high-performance device is fabricated with low-cost elements (the core components of the spectrometer cost less than US$15). The correlation between the spectral information and leaky mode images can be easily constructed after training. By solid packaging with a complementary metal-oxide semiconductor (CMOS) imaging sensor, the data acquisition of our spectrometer can be finished using a single snapshot with no external equipment needed.Ī lightweight vision transformer (ViT) network was used for analyzing the complex frames recorded by the CMOS image sensor (CIS). The spectrometer utilizes complex leaky modes speckles projected from a curved microfiber taper tip that uniquely determines the wavelength of the input signal. In a new paper published in eLight, a team of scientists led by Professor Yaoguang Ma from Zhejiang University have developed a compact spectrometer that integrates multiple taper tips for hyperspectral imaging. On-chip spectrometers rely on nanofabrication and tend to have very low coupling efficiency for wideband operation.Ībove all, a flexible and low-cost tiny spectrometer with stable high performance is still elusive. Generally, spectrometers with dispersive elements require extra spatial separations and tend to leave a large footprint.įilters (including narrowband and reconstructive types) based designs suffer from power loss caused by either absorption or reflection and limited resolution and bandwidth due to limited channel numbers. However, an inherent trade-off between the above aspects constrains this long-term theme of miniaturization from advancing. Researchers have been engineering spectrometers for lower cost, higher flexibilities, smaller size, better stabilities, and performances for quite some time.
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