Ytterbium (Tb) doped double-cladding fiber (DCF) lasers and amplifiers are being developed for a number of industrial and military applications. There are several key factors for maximizing the output power of these devices. Lambda Istruments is concentrating on two areas: component development and optical fiber development. The component development effort has focused on grating devices and pump couplers. Stable, highly reflective short-period fiber Bragg gratings are produced in DCF rapidly, have low insertion loss and can be customized for many different laser/amplifier applications. Long-period gratings are also being developed for possible novel use in fiber laser and amplifier applications. A proprietary fiber coupler under development is currently capable of an 85% coupling efficiency. The second focus for Lambda is the development of polarization maintaining Yb-doped DCF. Recent efforts have shifted towards making large mode area versions of these fibers to reduce nonlinear effects at high powers.