Dual Core Ytterbium Doped Fiber Ring Laser in Fourier Domain Mode Locked Operation for Swept-Source Optical Coherence Tomography

摘要

We demonstrate high efficiency and wide bandwidth gain in a Ytterbium doped fiber amplifier. The high-powered amplifier has potential applications for use with a swept-source fiber ring laser in multi-channel optical coherence tomography (OCT) system. The ring cavity design includes a 976nm pumped dual core Yb doped fiber as the gain medium, where a rotating polygon mirror is used as a wavelength-sweeping filter for this source. The amplified spontaneous emission (ASE) had a spectral bandwidth of 1037-1145nm at -60dBm, where a tunable lasing bandwidth of the ring cavity ranged from 1057-1115nm. The highest output power, for both the ASE and lasing spectrum, with this configuration was ~200mW, however it is possible to have a larger bandwidth and a larger output power. Higher power, in the wattage range is achievable if free space components are employed. Pumped with 976nm light at 1.27W, the use of this novel dual core Yb doped fiber as an amplifier has been successfully demonstrated, as it provided a small signal gain of 29.6 dB at 1085nm, where the gain medium was successfully saturated during operation. This is important for the spectral shaping requirements of OCT to improve image quality. The gain was demonstrated for several different wavelengths and for several pumping powers at a 1085nm wavelength. Fourier domain mode locked operation (FDML) was achieved with a bandwidth of 15nm and a sweep rate of 51.4kHz. This laser source offers a low-cost, high power alternative for biomedical imaging with multi-channel optical coherence tomography.