Fabry-Perot filter frequency stabilization control for multiple ITU wavelengths reference

As the space between the channels of dense wavelength division multiplexing (DWDM) systems becomes narrower, a variety of equipment is needed to have more precise frequencies and greater frequency stability. The research of frequency standards in the 1.5 μm region has become a hot topic in the optical communication area. In this paper, the frequency locking method of semiconductor lasers has been analyzed. In order to provide multiple ITU wavelength references for DWDM applications, a novel Fabry-Perot (F-P) filter frequency stabilization control system is presented. A frequency stabilized fiber Bragg grating (FBG) external cavity laser diode (ECLD) using acetylene (C₂H₂) has been fabricated. With the lock-in amplifier and the FBG ECLD stabilized by absorption of C₂H₂ as the reference, one transmission peak of Fabry-Perot inserted in the external cavity is locked at a 1530.3 nm peak of C₂H₂ to keep all of its transmission peaks stable, such that the F-P filter with 100 GHz spacing generates a stable and precise wavelength comb, and provides a set of ITU standards at the 1.55 μm wavelength band. Our setup is useful for frequency lock-in or frequency measurement and calibration and is promising for DWDM communication systems.