A fiber Raman laser is configured with a microstructured double clad passive fiber which has an inner cladding receiving and guiding a high intensity pump light. The double-clad passive fiber farther has a eon surrounded by the inner cladding and an outer cladding. An arrangement of air holes is configured to define the inner, waveguiding cladding so that an NA of the latter varies between about 0.25-0.9 allowing this to reduce the diameter of the inner cladding. The passive fiber is characterized by a substantial overlap between the pump light and 1st stokes in the care and further includes an absorber operative to substantially suppress the signal light at the 2nd strokes so that the Ge-doped fiber outputs a SM, bright radiation at up to kW levels.