Fiber light source with high mean wavelength stability and reliability

A broadband light source (10) configured to emit a stable broadband optical beam is provided. The broadband light source includes at least one optical pump source (100), an optical system (15) including a polarization beam combiner (120), and a solid state laser medium (140). The optical system is configured to receive at least one optical pump beam from a respective one of the at least one optical pump source. The solid state laser medium receives a substantially unpolarized pump beam from a first output of the optical system. Stable broadband amplified spontaneous emission is output from a second output of the optical system.