Combined Dual-Cavity Fourier Domain Mode Locked Laser

Fourier domain mode locking (FDML) wavelength-swept laser source have a crucial function in the field of swept-source optical coherence tomography (SS-OCT); however, up to now, the imaging depth and axial resolution cannot be improved simultaneously by changing the swept spectrum of swept source in OCT system. Therefore, a new ring resonator arrangement based on a Brillouin fiber laser structure is demonstrated. Light is recirculated continuously in the dual cavity comprising the optical bandpass filter, which is used as a switch, in contrast to a standard Fourier domain mode-locked configuration. At the same time, there have been advances in narrow linewidth of Brillouin fiber laser, and optical bandwidths can be broadened, but with limited output power. Based on the combined dual-cavity Fourier domain mode locking (cdc-FDML), the imaging depth could be as much as 1.37 times deeper than that of standard FDML configuration. Indeed, we observe that the axial resolution of combined dual-cavity configuration could be higher than that of standard FDML configuration. Characteristic features of cdc-FDML operation are investigated.

Automated summary

By improving the structure of FDML wavelength-swept laser source, deeper imaging depth and higher axial resolution can be achieved. The application of a Brillouin fiber laser structure and combined dual-cavity FDML configuration allows the new ring resonator arrangement to play an important role in optical coherence tomography.