ABSTRACT¾ We created a new design for an Nd-doped clad-pumped silica fiber laser to enhance the pump absor ption and lasing efficiency for a butt-coupled, end-pumped scheme. Two concatenated adiabatic tapers formed within the laser cavity simultaneously removed higher order modes and were spliced to conventional single mode fibers. We theoretically analyzed mode propagation along the composite cavity and experimentally achieved continuous wave oscillation in the LP 01 mode at 1.06 mm and a laser output power of over 820 mW with a slope e fficiency of 27%. I. INTRODUCTION The rapid development of arrayed semiconductor laser diodes (LDs) with high output power has influenced many applic ations in optical communications, especially high power fiber amplifiers and fiber lasers. The beam quality parameters of the arrayed LDs, however, are not compatible with those of conventional single mode fiber (SMF). To overcome this mode mismatch and increase power delivery, some researchers have developed laser cavities based on double clad fiber (DCF), in which the pump and signal beams have different optical paths interacting with each other over the length of the cavities [1], [2]. The pump is launched in the silica cladding waveguide with a large area and a high numerical aperture supported by a low refractive index polymer jacket.