SIMBAD references

The coherent-dispersion spectrometer (CODES) for exoplanet detection relies on the radial velocity (RV) method, detecting exoplanets by measuring the Doppler shifts in the stellar spectrum. The CODES utilizes a novel asymmetric designed Sagnac interferometer, which amplifies the minute wavelength shifts caused by Doppler shifts, converting them into more sensitive phase variations of the interference fringes. To investigate the detection capability of an individual spectral line on CODES, this paper develops a new RV retrieval algorithm MOST (Maximum likelihood estimation Optimized via Sequential quadratic programming and Tuna search optimization), which is based on the relationship between photon arrival probability and interference fringes and incorporates the statistical characteristics of photon Poisson distribution to achieve parameter estimation. The zero-finding problem in the Maximum Likelihood Estimation (MLE) is transformed into an optimization problem. Further, the Tuna Search Optimization algorithm and Sequential Quadratic Programming algorithm are utilized to solve the unknown model parameters in the MLE. The Monte Carlo simulation results demonstrate that under a noise-free environment, the RV retrieval precision for an individual spectral line can reach a level below 0.1 m s^–1. In the presence of noise, the retrieval precision can maintain within 1.0 m s^–1 when the signal-to-noise ratio reaches 92.4 for absorption line, and 85.7 for emission line. Further laser Doppler shift experiments on CODES show an average absolute error of -0.27 m s^–1. This study provides the first RV detection capability of CODES with an individual line, offering valuable theoretical guidance and technical reference for the design of high-precision RV measurement methods and high-resolution astronomical spectrometers.