A laser apparatus includes an optical fiber component and a pump light source coupled to the optical fiber component. The optical fiber component includes a first fiber segment, a second fiber segment and a connecting segment that connects the first and second fiber segments. The first fiber segment includes a fiber core having a first diameter, and the second fiber segment includes a fiber core having a second diameter. The first diameter may be greater than the second diameter, and the connecting segment may have a periodically varying refractive index.
