Specialty fibers for high power lasers and amplifiers

This paper reviews our recent work on novel large-mode area fibers for high power lasers and amplifiers. An ultra-low- NA fiber and single-trench fiber have been proposed for mode area scaling of the fundamental mode. In case of single-trench fiber design, resonant coupling of the higher order modes has been exploited to achieve effective single mode operation in fiber with large effective mode area. Our proposed fiber designs are easy to fabricate using conventional low-loss fiber fabrication techniques, and moreover, being all solid structure, they ensure easy cleaving and splicing. A monolithic and compact high power fiber laser/amplifier device with a good output beam quality can be achieved using Single-trench fiber design.