Now, tapered double-clad fiber (T-DCF) amplifiers offer the prospect of high power with excellent beam properties. Developed in the European PULSE project, which includes Tampere University and Ampliconyx Oy (both in Tampere, Finland), T-DCF is a double-clad optical fiber formed using a fiber-drawing process that forms a taper along the length of the fiber. Both the core and cladding are tapered; the result of the changing fiber parameters is a chain of fiber amplifiers with ever-growing core diameter, combining features of conventional small-diameter, double-clad single-mode fibers with those of much larger-diameter, double-clad multimode fibers used for high-power amplification. (See “Tapered double-clad fiber: The future of ultrafast high-power laser processing,” May 2020 issue; https://bit.ly/2020TechRev3.)