Frequency-Stabilized External Cavity Diode Laser at 1572 nm Based on Frequency Stability Transfer

A frequency-stabilized narrow-linewidth external cavity diode laser (ECDL) at the wavelength of the R18 carbon dioxide (CO
₂
) absorption line for space-borne CO
₂
detection LIDAR is reported. The ECDL module based on the fiber Bragg grating (FBG) is integrated in a compact butterfly package, emitting at the wavelength of 1572.02 nm and provides continuous tunability of 22 GHz. A polarization-maintaining all-fiber ring resonator is used as a transfer cavity to transfer the long-term stability of a metrological frequency reference at 1550.12 nm to the target wavelength. The combination of narrowing linewidth technique and frequency stability transfer technique enables lasing with an intrinsic Lorentzian linewidth of 15 kHz as well as a relative frequency stability on the order of
$10^{-12}$
for averaging time from 1 to 1000 s (minimum of
$2.1\times 10^{-12}$
at 2 s).