Hyperfine structure of molecular-iodine absorption spectroscopy at 561nm

An 1123-nm single-frequency laser with 1-W output power has been made by home, and 10-mW output power double frequency at 561 nm is obtained. The modulation transform spectroscopy is used to scan the hyperfine structure lines of molecular iodine absorption spectroscopy transitions at 561 nm. Four transition spectroscopy bands of ¹²⁷I₂ are observed, and transitions of P(58)22-1 and R(62)22-1 are discussed to be references of 561-nm ¹²⁷I₂ optical frequency standard.