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Spectrograph is one of the most important tools in astronomical observation and can be used in research areas ranging from cosmology to exoplanet research. Conventional astronomical spectrograph using a diffraction grating is huge, posing great challenges to their thermal and mechanical stability, and they are also very expensive. This inevitably determines the need for new original innovations in future optical and near-infrared spectrograph technologies. The application of photonics in astronomical spectrograph in recent years has shown a great potential for miniaturizing the spectrograph which is mounted on the large telescopes. The new dispersion element named waveguide spectral lens (WSL)is proposed by Westlake University that different from the independent optical element in the conventional spectrograph, and it can realize the dual functions of both wavelength separation and focus. This kind of chip technology makes the structure more compact, and improves the design to expand the devices working in the communication band to the visible and near-infrared band, enabling the spectrograph based on this new technology to achieve astronomical observation in the visible band in the future. In order to fully understand the performance of this new dispersion element and its application potential in astronomy, we established two chip test platforms in the optical laboratory of Shanghai Astronomical Observatory, and analyzed the dispersion capability of the device by using the wavelength calibration method. In order to expand the range of the spectra, the two-dimensional cross-dispersion spectrum was realized by adding a cylindrical lens and a blazed grating in the laboratory. The solar spectrum is also observed using these two chips. The experimental results show that this new optical waveguide chip can be applied to the visible light band, and can be used as the dispersion element of astronomical spectrograph for astronomical applications. At present, the optical and mechanical design of the prototype of the spectrograph has been completed. In the future, the laboratory installation of the prototype will be completed to realize the on-sky observation as soon as possible.
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