The supplementary material provides detailed insights into the design, efficiency, and performance of a monolithic thin-film lithium niobate broadband spectrometer with one-nanometre resolution. Key points include: 1. **Device Efficiency**: - The device efficiency is calculated using the formula \(\eta = 2\kappa L \cdot \exp(-\kappa L)\), where \(\kappa\) is the linear attenuation factor and \(L\) is the sampling region length. - The optimal efficiency is achieved when \(\kappa L = 1\), with a maximum scattering efficiency of \(1.2\%\) per wire (or \(0.052\) dB/wire). - The nanowires are designed to be \(50\) nm wide to act as point samplers, with a metal thickness of \(17.5\) nm, achieving a scattering efficiency of \(1.1\%\) per wire. 2. **DC Drift and Data Analysis**: - The device is affected by DC drift, which causes chirping in the interferogram. - Calibration involves measuring the scattering efficiency of each EFS and correcting for chromatic dispersion. - Fast modulation and faster imaging systems are being explored to mitigate the DC drift effect. 3. **Measurement of Broadband Sources**: - The spectrometer successfully resolves a super-luminescent diode (SLED) with a resolution of \(\Delta\lambda = 2.4\) nm. - The measured FWHM is \(47.9\) nm, with a \(6\%\) deviation from the commercial OSA value. 4. **Bandwidth Limitations and Multi-Mode Operation**: - The bandwidth is limited by the single-mode condition of the waveguides, which starts around \(1200\) nm and extends to over \(2000\) nm. - Multi-mode operation at shorter wavelengths is challenging due to mode-mixing, which complicates pattern reconstruction. - Simulations show that the waveguide supports up to the third-order TE mode at \(1064\) nm, leading to mode-mixing and interference patterns. The supplementary material also includes figures and simulations to support these findings, providing a comprehensive understanding of the device's performance and limitations.The supplementary material provides detailed insights into the design, efficiency, and performance of a monolithic thin-film lithium niobate broadband spectrometer with one-nanometre resolution. Key points include: 1. **Device Efficiency**: - The device efficiency is calculated using the formula \(\eta = 2\kappa L \cdot \exp(-\kappa L)\), where \(\kappa\) is the linear attenuation factor and \(L\) is the sampling region length. - The optimal efficiency is achieved when \(\kappa L = 1\), with a maximum scattering efficiency of \(1.2\%\) per wire (or \(0.052\) dB/wire). - The nanowires are designed to be \(50\) nm wide to act as point samplers, with a metal thickness of \(17.5\) nm, achieving a scattering efficiency of \(1.1\%\) per wire. 2. **DC Drift and Data Analysis**: - The device is affected by DC drift, which causes chirping in the interferogram. - Calibration involves measuring the scattering efficiency of each EFS and correcting for chromatic dispersion. - Fast modulation and faster imaging systems are being explored to mitigate the DC drift effect. 3. **Measurement of Broadband Sources**: - The spectrometer successfully resolves a super-luminescent diode (SLED) with a resolution of \(\Delta\lambda = 2.4\) nm. - The measured FWHM is \(47.9\) nm, with a \(6\%\) deviation from the commercial OSA value. 4. **Bandwidth Limitations and Multi-Mode Operation**: - The bandwidth is limited by the single-mode condition of the waveguides, which starts around \(1200\) nm and extends to over \(2000\) nm. - Multi-mode operation at shorter wavelengths is challenging due to mode-mixing, which complicates pattern reconstruction. - Simulations show that the waveguide supports up to the third-order TE mode at \(1064\) nm, leading to mode-mixing and interference patterns. The supplementary material also includes figures and simulations to support these findings, providing a comprehensive understanding of the device's performance and limitations.