High-resolution spectroscopy of molecular iodine using a narrow-linewidth laser at telecom wavelength

Frequency-stabilized lasers at the telecom wavelengths are of great interest for a wide range of applications, including wavelength standards for optical communication systems [1] , and an absolute frequency marker of an optical frequency comb. For frequency standards at the telecom wavelength, the acetylene combination band transitions are widely investigated [1] . The optical frequency of the P(16) transition line in the ν 1 + ν 3 band is recommended by the international committee for weights and measures (CIPM). However, such transitions are relatively weak for frequency stabilization to realize high frequency stability. On the other hand, molecular iodine has relatively strong absorption lines in the 500-nm wavelength region. Highly stable and reliable iodine-stabilized lasers have been realized by using the frequency-doubled 1-μm lasers [2] .