Compact speckle spectrometer using femtosecond laser-induced double-sided surface nanostructures

Area of Science:

• Optics and Photonics
• Spectroscopy
• Materials Science

Background:

• Speckle spectrometers utilize light scattering in disordered media for high sensitivity.
• Advances in all-fiber speckle spectrometers and planar scattering media are ongoing.
• Compact and cost-effective spectroscopic devices are in demand.

Purpose of the Study:

• To design and demonstrate a compact speckle spectrometer.
• To utilize femtosecond laser-induced nanostructures on quartz glass as a scattering medium.
• To achieve high spectral resolution and broad bandwidth reconstruction.

Main Methods:

• Fabrication of a scattering medium using femtosecond laser-induced double-sided nanostructures on quartz glass.
• Calibration of the transmission matrix for spectral reconstruction.
• Integration of neural networks (ResNet-50 and GRU) for enhanced spectral resolution and pattern recognition.

Main Results:

• Reconstruction of spectra over a 100 nm bandwidth with 0.1 nm spectral resolution.
• Demonstration of 5 pm spectral resolution within 100 pm bandwidths at specific wavelengths (1500, 1550, 1600 nm).
• Accurate reconstruction of a 2 nm bandwidth simulated continuous spectrum using combined neural networks.

Conclusions:

• The developed compact speckle spectrometer offers a novel approach to high-resolution spectroscopy.
• The device exhibits advantages such as low cost, small size, simple preparation, and repeatability.
• This technology holds promise for various applications requiring sensitive and compact spectral analysis.