Ultra-broadband optical amplifiers based on bismuth-doped heterogeneous-core fibers.

We report on the development of a cladding-pumped ultra-broadband optical amplifier for a spectral region of 1260-1480 nm using a Bi-doped fiber (BDF) with heterogeneous core formed by combination of PO- and GeO-containing glass layers. This BDF design ensures a favorable local environment for the effective formation process of BACs associated with P and Si atoms. The BDF amplifier (BDFA) pumped into the cladding by multi-mode laser diodes at 793 and 808 nm is characterized by a peak gain of ≈24 dB, a minimum noise figure of ≈6 dB, and a bandwidth of ≈160 nm at a gain level of 20 dB.

Supermode lasing and light amplification in multicore bismuth-doped fiber.

Multicore fibers are promising structures with specific light propagation properties, which can be managed to benefit several applications in optical communications, fiber lasers and amplifiers, high-resolution imaging, and fiber-based sensors. The current use of multicore fibers in laser technology is mainly focused on in-phase coherent beam combining in far-field regions (out-cavity) using bulk optical elements. However, this approach is challenging in terms of the power scalability of all-fiber lasers (intra-cavity), particularly with using low-gain media, where it is needed to provide mode-coupling (supermode propagation) stability along relatively long lengths.